treewide: remove redundant IS_ERR() before error code check

[linux/fpc-iii.git] / drivers / gpu / drm / i915 / i915_cmd_parser.c

/*
 * Copyright © 2013 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 * Authors:
 *    Brad Volkin <bradley.d.volkin@intel.com>
 *
 */

#include "gt/intel_engine.h"

#include "i915_drv.h"
#include "i915_memcpy.h"

/**
 * DOC: batch buffer command parser
 *
 * Motivation:
 * Certain OpenGL features (e.g. transform feedback, performance monitoring)
 * require userspace code to submit batches containing commands such as
 * MI_LOAD_REGISTER_IMM to access various registers. Unfortunately, some
 * generations of the hardware will noop these commands in "unsecure" batches
 * (which includes all userspace batches submitted via i915) even though the
 * commands may be safe and represent the intended programming model of the
 * device.
 *
 * The software command parser is similar in operation to the command parsing
 * done in hardware for unsecure batches. However, the software parser allows
 * some operations that would be noop'd by hardware, if the parser determines
 * the operation is safe, and submits the batch as "secure" to prevent hardware
 * parsing.
 *
 * Threats:
 * At a high level, the hardware (and software) checks attempt to prevent
 * granting userspace undue privileges. There are three categories of privilege.
 *
 * First, commands which are explicitly defined as privileged or which should
 * only be used by the kernel driver. The parser rejects such commands
 *
 * Second, commands which access registers. To support correct/enhanced
 * userspace functionality, particularly certain OpenGL extensions, the parser
 * provides a whitelist of registers which userspace may safely access
 *
 * Third, commands which access privileged memory (i.e. GGTT, HWS page, etc).
 * The parser always rejects such commands.
 *
 * The majority of the problematic commands fall in the MI_* range, with only a
 * few specific commands on each engine (e.g. PIPE_CONTROL and MI_FLUSH_DW).
 *
 * Implementation:
 * Each engine maintains tables of commands and registers which the parser
 * uses in scanning batch buffers submitted to that engine.
 *
 * Since the set of commands that the parser must check for is significantly
 * smaller than the number of commands supported, the parser tables contain only
 * those commands required by the parser. This generally works because command
 * opcode ranges have standard command length encodings. So for commands that
 * the parser does not need to check, it can easily skip them. This is
 * implemented via a per-engine length decoding vfunc.
 *
 * Unfortunately, there are a number of commands that do not follow the standard
 * length encoding for their opcode range, primarily amongst the MI_* commands.
 * To handle this, the parser provides a way to define explicit "skip" entries
 * in the per-engine command tables.
 *
 * Other command table entries map fairly directly to high level categories
 * mentioned above: rejected, register whitelist. The parser implements a number
 * of checks, including the privileged memory checks, via a general bitmasking
 * mechanism.
 */

/*
 * A command that requires special handling by the command parser.
 */
struct drm_i915_cmd_descriptor {
        /*
         * Flags describing how the command parser processes the command.
         *
         * CMD_DESC_FIXED: The command has a fixed length if this is set,
         *                 a length mask if not set
         * CMD_DESC_SKIP: The command is allowed but does not follow the
         *                standard length encoding for the opcode range in
         *                which it falls
         * CMD_DESC_REJECT: The command is never allowed
         * CMD_DESC_REGISTER: The command should be checked against the
         *                    register whitelist for the appropriate ring
         */
        u32 flags;
#define CMD_DESC_FIXED    (1<<0)
#define CMD_DESC_SKIP     (1<<1)
#define CMD_DESC_REJECT   (1<<2)
#define CMD_DESC_REGISTER (1<<3)
#define CMD_DESC_BITMASK  (1<<4)

        /*
         * The command's unique identification bits and the bitmask to get them.
         * This isn't strictly the opcode field as defined in the spec and may
         * also include type, subtype, and/or subop fields.
         */
        struct {
                u32 value;
                u32 mask;
        } cmd;

        /*
         * The command's length. The command is either fixed length (i.e. does
         * not include a length field) or has a length field mask. The flag
         * CMD_DESC_FIXED indicates a fixed length. Otherwise, the command has
         * a length mask. All command entries in a command table must include
         * length information.
         */
        union {
                u32 fixed;
                u32 mask;
        } length;

        /*
         * Describes where to find a register address in the command to check
         * against the ring's register whitelist. Only valid if flags has the
         * CMD_DESC_REGISTER bit set.
         *
         * A non-zero step value implies that the command may access multiple
         * registers in sequence (e.g. LRI), in that case step gives the
         * distance in dwords between individual offset fields.
         */
        struct {
                u32 offset;
                u32 mask;
                u32 step;
        } reg;

#define MAX_CMD_DESC_BITMASKS 3
        /*
         * Describes command checks where a particular dword is masked and
         * compared against an expected value. If the command does not match
         * the expected value, the parser rejects it. Only valid if flags has
         * the CMD_DESC_BITMASK bit set. Only entries where mask is non-zero
         * are valid.
         *
         * If the check specifies a non-zero condition_mask then the parser
         * only performs the check when the bits specified by condition_mask
         * are non-zero.
         */
        struct {
                u32 offset;
                u32 mask;
                u32 expected;
                u32 condition_offset;
                u32 condition_mask;
        } bits[MAX_CMD_DESC_BITMASKS];
};

/*
 * A table of commands requiring special handling by the command parser.
 *
 * Each engine has an array of tables. Each table consists of an array of
 * command descriptors, which must be sorted with command opcodes in
 * ascending order.
 */
struct drm_i915_cmd_table {
        const struct drm_i915_cmd_descriptor *table;
        int count;
};

#define STD_MI_OPCODE_SHIFT  (32 - 9)
#define STD_3D_OPCODE_SHIFT  (32 - 16)
#define STD_2D_OPCODE_SHIFT  (32 - 10)
#define STD_MFX_OPCODE_SHIFT (32 - 16)
#define MIN_OPCODE_SHIFT 16

#define CMD(op, opm, f, lm, fl, ...)                            \
        {                                                       \
                .flags = (fl) | ((f) ? CMD_DESC_FIXED : 0),     \
                .cmd = { (op & ~0u << (opm)), ~0u << (opm) },   \
                .length = { (lm) },                             \
                __VA_ARGS__                                     \
        }

/* Convenience macros to compress the tables */
#define SMI STD_MI_OPCODE_SHIFT
#define S3D STD_3D_OPCODE_SHIFT
#define S2D STD_2D_OPCODE_SHIFT
#define SMFX STD_MFX_OPCODE_SHIFT
#define F true
#define S CMD_DESC_SKIP
#define R CMD_DESC_REJECT
#define W CMD_DESC_REGISTER
#define B CMD_DESC_BITMASK

/*            Command                          Mask   Fixed Len   Action
              ---------------------------------------------------------- */
static const struct drm_i915_cmd_descriptor gen7_common_cmds[] = {
        CMD(  MI_NOOP,                          SMI,    F,  1,      S  ),
        CMD(  MI_USER_INTERRUPT,                SMI,    F,  1,      R  ),
        CMD(  MI_WAIT_FOR_EVENT,                SMI,    F,  1,      R  ),
        CMD(  MI_ARB_CHECK,                     SMI,    F,  1,      S  ),
        CMD(  MI_REPORT_HEAD,                   SMI,    F,  1,      S  ),
        CMD(  MI_SUSPEND_FLUSH,                 SMI,    F,  1,      S  ),
        CMD(  MI_SEMAPHORE_MBOX,                SMI,   !F,  0xFF,   R  ),
        CMD(  MI_STORE_DWORD_INDEX,             SMI,   !F,  0xFF,   R  ),
        CMD(  MI_LOAD_REGISTER_IMM(1),          SMI,   !F,  0xFF,   W,
              .reg = { .offset = 1, .mask = 0x007FFFFC, .step = 2 }    ),
        CMD(  MI_STORE_REGISTER_MEM,            SMI,    F,  3,     W | B,
              .reg = { .offset = 1, .mask = 0x007FFFFC },
              .bits = {{
                        .offset = 0,
                        .mask = MI_GLOBAL_GTT,
                        .expected = 0,
              }},                                                      ),
        CMD(  MI_LOAD_REGISTER_MEM,             SMI,    F,  3,     W | B,
              .reg = { .offset = 1, .mask = 0x007FFFFC },
              .bits = {{
                        .offset = 0,
                        .mask = MI_GLOBAL_GTT,
                        .expected = 0,
              }},                                                      ),
        /*
         * MI_BATCH_BUFFER_START requires some special handling. It's not
         * really a 'skip' action but it doesn't seem like it's worth adding
         * a new action. See intel_engine_cmd_parser().
         */
        CMD(  MI_BATCH_BUFFER_START,            SMI,   !F,  0xFF,   S  ),
};

static const struct drm_i915_cmd_descriptor gen7_render_cmds[] = {
        CMD(  MI_FLUSH,                         SMI,    F,  1,      S  ),
        CMD(  MI_ARB_ON_OFF,                    SMI,    F,  1,      R  ),
        CMD(  MI_PREDICATE,                     SMI,    F,  1,      S  ),
        CMD(  MI_TOPOLOGY_FILTER,               SMI,    F,  1,      S  ),
        CMD(  MI_SET_APPID,                     SMI,    F,  1,      S  ),
        CMD(  MI_DISPLAY_FLIP,                  SMI,   !F,  0xFF,   R  ),
        CMD(  MI_SET_CONTEXT,                   SMI,   !F,  0xFF,   R  ),
        CMD(  MI_URB_CLEAR,                     SMI,   !F,  0xFF,   S  ),
        CMD(  MI_STORE_DWORD_IMM,               SMI,   !F,  0x3F,   B,
              .bits = {{
                        .offset = 0,
                        .mask = MI_GLOBAL_GTT,
                        .expected = 0,
              }},                                                      ),
        CMD(  MI_UPDATE_GTT,                    SMI,   !F,  0xFF,   R  ),
        CMD(  MI_CLFLUSH,                       SMI,   !F,  0x3FF,  B,
              .bits = {{
                        .offset = 0,
                        .mask = MI_GLOBAL_GTT,
                        .expected = 0,
              }},                                                      ),
        CMD(  MI_REPORT_PERF_COUNT,             SMI,   !F,  0x3F,   B,
              .bits = {{
                        .offset = 1,
                        .mask = MI_REPORT_PERF_COUNT_GGTT,
                        .expected = 0,
              }},                                                      ),
        CMD(  MI_CONDITIONAL_BATCH_BUFFER_END,  SMI,   !F,  0xFF,   B,
              .bits = {{
                        .offset = 0,
                        .mask = MI_GLOBAL_GTT,
                        .expected = 0,
              }},                                                      ),
        CMD(  GFX_OP_3DSTATE_VF_STATISTICS,     S3D,    F,  1,      S  ),
        CMD(  PIPELINE_SELECT,                  S3D,    F,  1,      S  ),
        CMD(  MEDIA_VFE_STATE,                  S3D,   !F,  0xFFFF, B,
              .bits = {{
                        .offset = 2,
                        .mask = MEDIA_VFE_STATE_MMIO_ACCESS_MASK,
                        .expected = 0,
              }},                                                      ),
        CMD(  GPGPU_OBJECT,                     S3D,   !F,  0xFF,   S  ),
        CMD(  GPGPU_WALKER,                     S3D,   !F,  0xFF,   S  ),
        CMD(  GFX_OP_3DSTATE_SO_DECL_LIST,      S3D,   !F,  0x1FF,  S  ),
        CMD(  GFX_OP_PIPE_CONTROL(5),           S3D,   !F,  0xFF,   B,
              .bits = {{
                        .offset = 1,
                        .mask = (PIPE_CONTROL_MMIO_WRITE | PIPE_CONTROL_NOTIFY),
                        .expected = 0,
              },
              {
                        .offset = 1,
                        .mask = (PIPE_CONTROL_GLOBAL_GTT_IVB |
                                 PIPE_CONTROL_STORE_DATA_INDEX),
                        .expected = 0,
                        .condition_offset = 1,
                        .condition_mask = PIPE_CONTROL_POST_SYNC_OP_MASK,
              }},                                                      ),
};

static const struct drm_i915_cmd_descriptor hsw_render_cmds[] = {
        CMD(  MI_SET_PREDICATE,                 SMI,    F,  1,      S  ),
        CMD(  MI_RS_CONTROL,                    SMI,    F,  1,      S  ),
        CMD(  MI_URB_ATOMIC_ALLOC,              SMI,    F,  1,      S  ),
        CMD(  MI_SET_APPID,                     SMI,    F,  1,      S  ),
        CMD(  MI_RS_CONTEXT,                    SMI,    F,  1,      S  ),
        CMD(  MI_LOAD_SCAN_LINES_INCL,          SMI,   !F,  0x3F,   R  ),
        CMD(  MI_LOAD_SCAN_LINES_EXCL,          SMI,   !F,  0x3F,   R  ),
        CMD(  MI_LOAD_REGISTER_REG,             SMI,   !F,  0xFF,   W,
              .reg = { .offset = 1, .mask = 0x007FFFFC, .step = 1 }    ),
        CMD(  MI_RS_STORE_DATA_IMM,             SMI,   !F,  0xFF,   S  ),
        CMD(  MI_LOAD_URB_MEM,                  SMI,   !F,  0xFF,   S  ),
        CMD(  MI_STORE_URB_MEM,                 SMI,   !F,  0xFF,   S  ),
        CMD(  GFX_OP_3DSTATE_DX9_CONSTANTF_VS,  S3D,   !F,  0x7FF,  S  ),
        CMD(  GFX_OP_3DSTATE_DX9_CONSTANTF_PS,  S3D,   !F,  0x7FF,  S  ),

        CMD(  GFX_OP_3DSTATE_BINDING_TABLE_EDIT_VS,  S3D,   !F,  0x1FF,  S  ),
        CMD(  GFX_OP_3DSTATE_BINDING_TABLE_EDIT_GS,  S3D,   !F,  0x1FF,  S  ),
        CMD(  GFX_OP_3DSTATE_BINDING_TABLE_EDIT_HS,  S3D,   !F,  0x1FF,  S  ),
        CMD(  GFX_OP_3DSTATE_BINDING_TABLE_EDIT_DS,  S3D,   !F,  0x1FF,  S  ),
        CMD(  GFX_OP_3DSTATE_BINDING_TABLE_EDIT_PS,  S3D,   !F,  0x1FF,  S  ),
};

static const struct drm_i915_cmd_descriptor gen7_video_cmds[] = {
        CMD(  MI_ARB_ON_OFF,                    SMI,    F,  1,      R  ),
        CMD(  MI_SET_APPID,                     SMI,    F,  1,      S  ),
        CMD(  MI_STORE_DWORD_IMM,               SMI,   !F,  0xFF,   B,
              .bits = {{
                        .offset = 0,
                        .mask = MI_GLOBAL_GTT,
                        .expected = 0,
              }},                                                      ),
        CMD(  MI_UPDATE_GTT,                    SMI,   !F,  0x3F,   R  ),
        CMD(  MI_FLUSH_DW,                      SMI,   !F,  0x3F,   B,
              .bits = {{
                        .offset = 0,
                        .mask = MI_FLUSH_DW_NOTIFY,
                        .expected = 0,
              },
              {
                        .offset = 1,
                        .mask = MI_FLUSH_DW_USE_GTT,
                        .expected = 0,
                        .condition_offset = 0,
                        .condition_mask = MI_FLUSH_DW_OP_MASK,
              },
              {
                        .offset = 0,
                        .mask = MI_FLUSH_DW_STORE_INDEX,
                        .expected = 0,
                        .condition_offset = 0,
                        .condition_mask = MI_FLUSH_DW_OP_MASK,
              }},                                                      ),
        CMD(  MI_CONDITIONAL_BATCH_BUFFER_END,  SMI,   !F,  0xFF,   B,
              .bits = {{
                        .offset = 0,
                        .mask = MI_GLOBAL_GTT,
                        .expected = 0,
              }},                                                      ),
        /*
         * MFX_WAIT doesn't fit the way we handle length for most commands.
         * It has a length field but it uses a non-standard length bias.
         * It is always 1 dword though, so just treat it as fixed length.
         */
        CMD(  MFX_WAIT,                         SMFX,   F,  1,      S  ),
};

static const struct drm_i915_cmd_descriptor gen7_vecs_cmds[] = {
        CMD(  MI_ARB_ON_OFF,                    SMI,    F,  1,      R  ),
        CMD(  MI_SET_APPID,                     SMI,    F,  1,      S  ),
        CMD(  MI_STORE_DWORD_IMM,               SMI,   !F,  0xFF,   B,
              .bits = {{
                        .offset = 0,
                        .mask = MI_GLOBAL_GTT,
                        .expected = 0,
              }},                                                      ),
        CMD(  MI_UPDATE_GTT,                    SMI,   !F,  0x3F,   R  ),
        CMD(  MI_FLUSH_DW,                      SMI,   !F,  0x3F,   B,
              .bits = {{
                        .offset = 0,
                        .mask = MI_FLUSH_DW_NOTIFY,
                        .expected = 0,
              },
              {
                        .offset = 1,
                        .mask = MI_FLUSH_DW_USE_GTT,
                        .expected = 0,
                        .condition_offset = 0,
                        .condition_mask = MI_FLUSH_DW_OP_MASK,
              },
              {
                        .offset = 0,
                        .mask = MI_FLUSH_DW_STORE_INDEX,
                        .expected = 0,
                        .condition_offset = 0,
                        .condition_mask = MI_FLUSH_DW_OP_MASK,
              }},                                                      ),
        CMD(  MI_CONDITIONAL_BATCH_BUFFER_END,  SMI,   !F,  0xFF,   B,
              .bits = {{
                        .offset = 0,
                        .mask = MI_GLOBAL_GTT,
                        .expected = 0,
              }},                                                      ),
};

static const struct drm_i915_cmd_descriptor gen7_blt_cmds[] = {
        CMD(  MI_DISPLAY_FLIP,                  SMI,   !F,  0xFF,   R  ),
        CMD(  MI_STORE_DWORD_IMM,               SMI,   !F,  0x3FF,  B,
              .bits = {{
                        .offset = 0,
                        .mask = MI_GLOBAL_GTT,
                        .expected = 0,
              }},                                                      ),
        CMD(  MI_UPDATE_GTT,                    SMI,   !F,  0x3F,   R  ),
        CMD(  MI_FLUSH_DW,                      SMI,   !F,  0x3F,   B,
              .bits = {{
                        .offset = 0,
                        .mask = MI_FLUSH_DW_NOTIFY,
                        .expected = 0,
              },
              {
                        .offset = 1,
                        .mask = MI_FLUSH_DW_USE_GTT,
                        .expected = 0,
                        .condition_offset = 0,
                        .condition_mask = MI_FLUSH_DW_OP_MASK,
              },
              {
                        .offset = 0,
                        .mask = MI_FLUSH_DW_STORE_INDEX,
                        .expected = 0,
                        .condition_offset = 0,
                        .condition_mask = MI_FLUSH_DW_OP_MASK,
              }},                                                      ),
        CMD(  COLOR_BLT,                        S2D,   !F,  0x3F,   S  ),
        CMD(  SRC_COPY_BLT,                     S2D,   !F,  0x3F,   S  ),
};

static const struct drm_i915_cmd_descriptor hsw_blt_cmds[] = {
        CMD(  MI_LOAD_SCAN_LINES_INCL,          SMI,   !F,  0x3F,   R  ),
        CMD(  MI_LOAD_SCAN_LINES_EXCL,          SMI,   !F,  0x3F,   R  ),
};

/*
 * For Gen9 we can still rely on the h/w to enforce cmd security, and only
 * need to re-enforce the register access checks. We therefore only need to
 * teach the cmdparser how to find the end of each command, and identify
 * register accesses. The table doesn't need to reject any commands, and so
 * the only commands listed here are:
 *   1) Those that touch registers
 *   2) Those that do not have the default 8-bit length
 *
 * Note that the default MI length mask chosen for this table is 0xFF, not
 * the 0x3F used on older devices. This is because the vast majority of MI
 * cmds on Gen9 use a standard 8-bit Length field.
 * All the Gen9 blitter instructions are standard 0xFF length mask, and
 * none allow access to non-general registers, so in fact no BLT cmds are
 * included in the table at all.
 *
 */
static const struct drm_i915_cmd_descriptor gen9_blt_cmds[] = {
        CMD(  MI_NOOP,                          SMI,    F,  1,      S  ),
        CMD(  MI_USER_INTERRUPT,                SMI,    F,  1,      S  ),
        CMD(  MI_WAIT_FOR_EVENT,                SMI,    F,  1,      S  ),
        CMD(  MI_FLUSH,                         SMI,    F,  1,      S  ),
        CMD(  MI_ARB_CHECK,                     SMI,    F,  1,      S  ),
        CMD(  MI_REPORT_HEAD,                   SMI,    F,  1,      S  ),
        CMD(  MI_ARB_ON_OFF,                    SMI,    F,  1,      S  ),
        CMD(  MI_SUSPEND_FLUSH,                 SMI,    F,  1,      S  ),
        CMD(  MI_LOAD_SCAN_LINES_INCL,          SMI,   !F,  0x3F,   S  ),
        CMD(  MI_LOAD_SCAN_LINES_EXCL,          SMI,   !F,  0x3F,   S  ),
        CMD(  MI_STORE_DWORD_IMM,               SMI,   !F,  0x3FF,  S  ),
        CMD(  MI_LOAD_REGISTER_IMM(1),          SMI,   !F,  0xFF,   W,
              .reg = { .offset = 1, .mask = 0x007FFFFC, .step = 2 }    ),
        CMD(  MI_UPDATE_GTT,                    SMI,   !F,  0x3FF,  S  ),
        CMD(  MI_STORE_REGISTER_MEM_GEN8,       SMI,    F,  4,      W,
              .reg = { .offset = 1, .mask = 0x007FFFFC }               ),
        CMD(  MI_FLUSH_DW,                      SMI,   !F,  0x3F,   S  ),
        CMD(  MI_LOAD_REGISTER_MEM_GEN8,        SMI,    F,  4,      W,
              .reg = { .offset = 1, .mask = 0x007FFFFC }               ),
        CMD(  MI_LOAD_REGISTER_REG,             SMI,    !F,  0xFF,  W,
              .reg = { .offset = 1, .mask = 0x007FFFFC, .step = 1 }    ),

        /*
         * We allow BB_START but apply further checks. We just sanitize the
         * basic fields here.
         */
#define MI_BB_START_OPERAND_MASK   GENMASK(SMI-1, 0)
#define MI_BB_START_OPERAND_EXPECT (MI_BATCH_PPGTT_HSW | 1)
        CMD(  MI_BATCH_BUFFER_START_GEN8,       SMI,    !F,  0xFF,  B,
              .bits = {{
                        .offset = 0,
                        .mask = MI_BB_START_OPERAND_MASK,
                        .expected = MI_BB_START_OPERAND_EXPECT,
              }},                                                      ),
};

static const struct drm_i915_cmd_descriptor noop_desc =
        CMD(MI_NOOP, SMI, F, 1, S);

#undef CMD
#undef SMI
#undef S3D
#undef S2D
#undef SMFX
#undef F
#undef S
#undef R
#undef W
#undef B

static const struct drm_i915_cmd_table gen7_render_cmd_table[] = {
        { gen7_common_cmds, ARRAY_SIZE(gen7_common_cmds) },
        { gen7_render_cmds, ARRAY_SIZE(gen7_render_cmds) },
};

static const struct drm_i915_cmd_table hsw_render_ring_cmd_table[] = {
        { gen7_common_cmds, ARRAY_SIZE(gen7_common_cmds) },
        { gen7_render_cmds, ARRAY_SIZE(gen7_render_cmds) },
        { hsw_render_cmds, ARRAY_SIZE(hsw_render_cmds) },
};

static const struct drm_i915_cmd_table gen7_video_cmd_table[] = {
        { gen7_common_cmds, ARRAY_SIZE(gen7_common_cmds) },
        { gen7_video_cmds, ARRAY_SIZE(gen7_video_cmds) },
};

static const struct drm_i915_cmd_table hsw_vebox_cmd_table[] = {
        { gen7_common_cmds, ARRAY_SIZE(gen7_common_cmds) },
        { gen7_vecs_cmds, ARRAY_SIZE(gen7_vecs_cmds) },
};

static const struct drm_i915_cmd_table gen7_blt_cmd_table[] = {
        { gen7_common_cmds, ARRAY_SIZE(gen7_common_cmds) },
        { gen7_blt_cmds, ARRAY_SIZE(gen7_blt_cmds) },
};

static const struct drm_i915_cmd_table hsw_blt_ring_cmd_table[] = {
        { gen7_common_cmds, ARRAY_SIZE(gen7_common_cmds) },
        { gen7_blt_cmds, ARRAY_SIZE(gen7_blt_cmds) },
        { hsw_blt_cmds, ARRAY_SIZE(hsw_blt_cmds) },
};

static const struct drm_i915_cmd_table gen9_blt_cmd_table[] = {
        { gen9_blt_cmds, ARRAY_SIZE(gen9_blt_cmds) },
};


/*
 * Register whitelists, sorted by increasing register offset.
 */

/*
 * An individual whitelist entry granting access to register addr.  If
 * mask is non-zero the argument of immediate register writes will be
 * AND-ed with mask, and the command will be rejected if the result
 * doesn't match value.
 *
 * Registers with non-zero mask are only allowed to be written using
 * LRI.
 */
struct drm_i915_reg_descriptor {
        i915_reg_t addr;
        u32 mask;
        u32 value;
};

/* Convenience macro for adding 32-bit registers. */
#define REG32(_reg, ...) \
        { .addr = (_reg), __VA_ARGS__ }

/*
 * Convenience macro for adding 64-bit registers.
 *
 * Some registers that userspace accesses are 64 bits. The register
 * access commands only allow 32-bit accesses. Hence, we have to include
 * entries for both halves of the 64-bit registers.
 */
#define REG64(_reg) \
        { .addr = _reg }, \
        { .addr = _reg ## _UDW }

#define REG64_IDX(_reg, idx) \
        { .addr = _reg(idx) }, \
        { .addr = _reg ## _UDW(idx) }

static const struct drm_i915_reg_descriptor gen7_render_regs[] = {
        REG64(GPGPU_THREADS_DISPATCHED),
        REG64(HS_INVOCATION_COUNT),
        REG64(DS_INVOCATION_COUNT),
        REG64(IA_VERTICES_COUNT),
        REG64(IA_PRIMITIVES_COUNT),
        REG64(VS_INVOCATION_COUNT),
        REG64(GS_INVOCATION_COUNT),
        REG64(GS_PRIMITIVES_COUNT),
        REG64(CL_INVOCATION_COUNT),
        REG64(CL_PRIMITIVES_COUNT),
        REG64(PS_INVOCATION_COUNT),
        REG64(PS_DEPTH_COUNT),
        REG64_IDX(RING_TIMESTAMP, RENDER_RING_BASE),
        REG64(MI_PREDICATE_SRC0),
        REG64(MI_PREDICATE_SRC1),
        REG32(GEN7_3DPRIM_END_OFFSET),
        REG32(GEN7_3DPRIM_START_VERTEX),
        REG32(GEN7_3DPRIM_VERTEX_COUNT),
        REG32(GEN7_3DPRIM_INSTANCE_COUNT),
        REG32(GEN7_3DPRIM_START_INSTANCE),
        REG32(GEN7_3DPRIM_BASE_VERTEX),
        REG32(GEN7_GPGPU_DISPATCHDIMX),
        REG32(GEN7_GPGPU_DISPATCHDIMY),
        REG32(GEN7_GPGPU_DISPATCHDIMZ),
        REG64_IDX(RING_TIMESTAMP, BSD_RING_BASE),
        REG64_IDX(GEN7_SO_NUM_PRIMS_WRITTEN, 0),
        REG64_IDX(GEN7_SO_NUM_PRIMS_WRITTEN, 1),
        REG64_IDX(GEN7_SO_NUM_PRIMS_WRITTEN, 2),
        REG64_IDX(GEN7_SO_NUM_PRIMS_WRITTEN, 3),
        REG64_IDX(GEN7_SO_PRIM_STORAGE_NEEDED, 0),
        REG64_IDX(GEN7_SO_PRIM_STORAGE_NEEDED, 1),
        REG64_IDX(GEN7_SO_PRIM_STORAGE_NEEDED, 2),
        REG64_IDX(GEN7_SO_PRIM_STORAGE_NEEDED, 3),
        REG32(GEN7_SO_WRITE_OFFSET(0)),
        REG32(GEN7_SO_WRITE_OFFSET(1)),
        REG32(GEN7_SO_WRITE_OFFSET(2)),
        REG32(GEN7_SO_WRITE_OFFSET(3)),
        REG32(GEN7_L3SQCREG1),
        REG32(GEN7_L3CNTLREG2),
        REG32(GEN7_L3CNTLREG3),
        REG64_IDX(RING_TIMESTAMP, BLT_RING_BASE),
};

static const struct drm_i915_reg_descriptor hsw_render_regs[] = {
        REG64_IDX(HSW_CS_GPR, 0),
        REG64_IDX(HSW_CS_GPR, 1),
        REG64_IDX(HSW_CS_GPR, 2),
        REG64_IDX(HSW_CS_GPR, 3),
        REG64_IDX(HSW_CS_GPR, 4),
        REG64_IDX(HSW_CS_GPR, 5),
        REG64_IDX(HSW_CS_GPR, 6),
        REG64_IDX(HSW_CS_GPR, 7),
        REG64_IDX(HSW_CS_GPR, 8),
        REG64_IDX(HSW_CS_GPR, 9),
        REG64_IDX(HSW_CS_GPR, 10),
        REG64_IDX(HSW_CS_GPR, 11),
        REG64_IDX(HSW_CS_GPR, 12),
        REG64_IDX(HSW_CS_GPR, 13),
        REG64_IDX(HSW_CS_GPR, 14),
        REG64_IDX(HSW_CS_GPR, 15),
        REG32(HSW_SCRATCH1,
              .mask = ~HSW_SCRATCH1_L3_DATA_ATOMICS_DISABLE,
              .value = 0),
        REG32(HSW_ROW_CHICKEN3,
              .mask = ~(HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE << 16 |
                        HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE),
              .value = 0),
};

static const struct drm_i915_reg_descriptor gen7_blt_regs[] = {
        REG64_IDX(RING_TIMESTAMP, RENDER_RING_BASE),
        REG64_IDX(RING_TIMESTAMP, BSD_RING_BASE),
        REG32(BCS_SWCTRL),
        REG64_IDX(RING_TIMESTAMP, BLT_RING_BASE),
};

static const struct drm_i915_reg_descriptor gen9_blt_regs[] = {
        REG64_IDX(RING_TIMESTAMP, RENDER_RING_BASE),
        REG64_IDX(RING_TIMESTAMP, BSD_RING_BASE),
        REG32(BCS_SWCTRL),
        REG64_IDX(RING_TIMESTAMP, BLT_RING_BASE),
        REG64_IDX(BCS_GPR, 0),
        REG64_IDX(BCS_GPR, 1),
        REG64_IDX(BCS_GPR, 2),
        REG64_IDX(BCS_GPR, 3),
        REG64_IDX(BCS_GPR, 4),
        REG64_IDX(BCS_GPR, 5),
        REG64_IDX(BCS_GPR, 6),
        REG64_IDX(BCS_GPR, 7),
        REG64_IDX(BCS_GPR, 8),
        REG64_IDX(BCS_GPR, 9),
        REG64_IDX(BCS_GPR, 10),
        REG64_IDX(BCS_GPR, 11),
        REG64_IDX(BCS_GPR, 12),
        REG64_IDX(BCS_GPR, 13),
        REG64_IDX(BCS_GPR, 14),
        REG64_IDX(BCS_GPR, 15),
};

#undef REG64
#undef REG32

struct drm_i915_reg_table {
        const struct drm_i915_reg_descriptor *regs;
        int num_regs;
};

static const struct drm_i915_reg_table ivb_render_reg_tables[] = {
        { gen7_render_regs, ARRAY_SIZE(gen7_render_regs) },
};

static const struct drm_i915_reg_table ivb_blt_reg_tables[] = {
        { gen7_blt_regs, ARRAY_SIZE(gen7_blt_regs) },
};

static const struct drm_i915_reg_table hsw_render_reg_tables[] = {
        { gen7_render_regs, ARRAY_SIZE(gen7_render_regs) },
        { hsw_render_regs, ARRAY_SIZE(hsw_render_regs) },
};

static const struct drm_i915_reg_table hsw_blt_reg_tables[] = {
        { gen7_blt_regs, ARRAY_SIZE(gen7_blt_regs) },
};

static const struct drm_i915_reg_table gen9_blt_reg_tables[] = {
        { gen9_blt_regs, ARRAY_SIZE(gen9_blt_regs) },
};

static u32 gen7_render_get_cmd_length_mask(u32 cmd_header)
{
        u32 client = cmd_header >> INSTR_CLIENT_SHIFT;
        u32 subclient =
                (cmd_header & INSTR_SUBCLIENT_MASK) >> INSTR_SUBCLIENT_SHIFT;

        if (client == INSTR_MI_CLIENT)
                return 0x3F;
        else if (client == INSTR_RC_CLIENT) {
                if (subclient == INSTR_MEDIA_SUBCLIENT)
                        return 0xFFFF;
                else
                        return 0xFF;
        }

        DRM_DEBUG("CMD: Abnormal rcs cmd length! 0x%08X\n", cmd_header);
        return 0;
}

static u32 gen7_bsd_get_cmd_length_mask(u32 cmd_header)
{
        u32 client = cmd_header >> INSTR_CLIENT_SHIFT;
        u32 subclient =
                (cmd_header & INSTR_SUBCLIENT_MASK) >> INSTR_SUBCLIENT_SHIFT;
        u32 op = (cmd_header & INSTR_26_TO_24_MASK) >> INSTR_26_TO_24_SHIFT;

        if (client == INSTR_MI_CLIENT)
                return 0x3F;
        else if (client == INSTR_RC_CLIENT) {
                if (subclient == INSTR_MEDIA_SUBCLIENT) {
                        if (op == 6)
                                return 0xFFFF;
                        else
                                return 0xFFF;
                } else
                        return 0xFF;
        }

        DRM_DEBUG("CMD: Abnormal bsd cmd length! 0x%08X\n", cmd_header);
        return 0;
}

static u32 gen7_blt_get_cmd_length_mask(u32 cmd_header)
{
        u32 client = cmd_header >> INSTR_CLIENT_SHIFT;

        if (client == INSTR_MI_CLIENT)
                return 0x3F;
        else if (client == INSTR_BC_CLIENT)
                return 0xFF;

        DRM_DEBUG("CMD: Abnormal blt cmd length! 0x%08X\n", cmd_header);
        return 0;
}

static u32 gen9_blt_get_cmd_length_mask(u32 cmd_header)
{
        u32 client = cmd_header >> INSTR_CLIENT_SHIFT;

        if (client == INSTR_MI_CLIENT || client == INSTR_BC_CLIENT)
                return 0xFF;

        DRM_DEBUG("CMD: Abnormal blt cmd length! 0x%08X\n", cmd_header);
        return 0;
}

static bool validate_cmds_sorted(const struct intel_engine_cs *engine,
                                 const struct drm_i915_cmd_table *cmd_tables,
                                 int cmd_table_count)
{
        int i;
        bool ret = true;

        if (!cmd_tables || cmd_table_count == 0)
                return true;

        for (i = 0; i < cmd_table_count; i++) {
                const struct drm_i915_cmd_table *table = &cmd_tables[i];
                u32 previous = 0;
                int j;

                for (j = 0; j < table->count; j++) {
                        const struct drm_i915_cmd_descriptor *desc =
                                &table->table[j];
                        u32 curr = desc->cmd.value & desc->cmd.mask;

                        if (curr < previous) {
                                DRM_ERROR("CMD: %s [%d] command table not sorted: "
                                          "table=%d entry=%d cmd=0x%08X prev=0x%08X\n",
                                          engine->name, engine->id,
                                          i, j, curr, previous);
                                ret = false;
                        }

                        previous = curr;
                }
        }

        return ret;
}

static bool check_sorted(const struct intel_engine_cs *engine,
                         const struct drm_i915_reg_descriptor *reg_table,
                         int reg_count)
{
        int i;
        u32 previous = 0;
        bool ret = true;

        for (i = 0; i < reg_count; i++) {
                u32 curr = i915_mmio_reg_offset(reg_table[i].addr);

                if (curr < previous) {
                        DRM_ERROR("CMD: %s [%d] register table not sorted: "
                                  "entry=%d reg=0x%08X prev=0x%08X\n",
                                  engine->name, engine->id,
                                  i, curr, previous);
                        ret = false;
                }

                previous = curr;
        }

        return ret;
}

static bool validate_regs_sorted(struct intel_engine_cs *engine)
{
        int i;
        const struct drm_i915_reg_table *table;

        for (i = 0; i < engine->reg_table_count; i++) {
                table = &engine->reg_tables[i];
                if (!check_sorted(engine, table->regs, table->num_regs))
                        return false;
        }

        return true;
}

struct cmd_node {
        const struct drm_i915_cmd_descriptor *desc;
        struct hlist_node node;
};

/*
 * Different command ranges have different numbers of bits for the opcode. For
 * example, MI commands use bits 31:23 while 3D commands use bits 31:16. The
 * problem is that, for example, MI commands use bits 22:16 for other fields
 * such as GGTT vs PPGTT bits. If we include those bits in the mask then when
 * we mask a command from a batch it could hash to the wrong bucket due to
 * non-opcode bits being set. But if we don't include those bits, some 3D
 * commands may hash to the same bucket due to not including opcode bits that
 * make the command unique. For now, we will risk hashing to the same bucket.
 */
static inline u32 cmd_header_key(u32 x)
{
        switch (x >> INSTR_CLIENT_SHIFT) {
        default:
        case INSTR_MI_CLIENT:
                return x >> STD_MI_OPCODE_SHIFT;
        case INSTR_RC_CLIENT:
                return x >> STD_3D_OPCODE_SHIFT;
        case INSTR_BC_CLIENT:
                return x >> STD_2D_OPCODE_SHIFT;
        }
}

static int init_hash_table(struct intel_engine_cs *engine,
                           const struct drm_i915_cmd_table *cmd_tables,
                           int cmd_table_count)
{
        int i, j;

        hash_init(engine->cmd_hash);

        for (i = 0; i < cmd_table_count; i++) {
                const struct drm_i915_cmd_table *table = &cmd_tables[i];

                for (j = 0; j < table->count; j++) {
                        const struct drm_i915_cmd_descriptor *desc =
                                &table->table[j];
                        struct cmd_node *desc_node =
                                kmalloc(sizeof(*desc_node), GFP_KERNEL);

                        if (!desc_node)
                                return -ENOMEM;

                        desc_node->desc = desc;
                        hash_add(engine->cmd_hash, &desc_node->node,
                                 cmd_header_key(desc->cmd.value));
                }
        }

        return 0;
}

static void fini_hash_table(struct intel_engine_cs *engine)
{
        struct hlist_node *tmp;
        struct cmd_node *desc_node;
        int i;

        hash_for_each_safe(engine->cmd_hash, i, tmp, desc_node, node) {
                hash_del(&desc_node->node);
                kfree(desc_node);
        }
}

/**
 * intel_engine_init_cmd_parser() - set cmd parser related fields for an engine
 * @engine: the engine to initialize
 *
 * Optionally initializes fields related to batch buffer command parsing in the
 * struct intel_engine_cs based on whether the platform requires software
 * command parsing.
 */
void intel_engine_init_cmd_parser(struct intel_engine_cs *engine)
{
        const struct drm_i915_cmd_table *cmd_tables;
        int cmd_table_count;
        int ret;

        if (!IS_GEN(engine->i915, 7) && !(IS_GEN(engine->i915, 9) &&
                                          engine->class == COPY_ENGINE_CLASS))
                return;

        switch (engine->class) {
        case RENDER_CLASS:
                if (IS_HASWELL(engine->i915)) {
                        cmd_tables = hsw_render_ring_cmd_table;
                        cmd_table_count =
                                ARRAY_SIZE(hsw_render_ring_cmd_table);
                } else {
                        cmd_tables = gen7_render_cmd_table;
                        cmd_table_count = ARRAY_SIZE(gen7_render_cmd_table);
                }

                if (IS_HASWELL(engine->i915)) {
                        engine->reg_tables = hsw_render_reg_tables;
                        engine->reg_table_count = ARRAY_SIZE(hsw_render_reg_tables);
                } else {
                        engine->reg_tables = ivb_render_reg_tables;
                        engine->reg_table_count = ARRAY_SIZE(ivb_render_reg_tables);
                }
                engine->get_cmd_length_mask = gen7_render_get_cmd_length_mask;
                break;
        case VIDEO_DECODE_CLASS:
                cmd_tables = gen7_video_cmd_table;
                cmd_table_count = ARRAY_SIZE(gen7_video_cmd_table);
                engine->get_cmd_length_mask = gen7_bsd_get_cmd_length_mask;
                break;
        case COPY_ENGINE_CLASS:
                engine->get_cmd_length_mask = gen7_blt_get_cmd_length_mask;
                if (IS_GEN(engine->i915, 9)) {
                        cmd_tables = gen9_blt_cmd_table;
                        cmd_table_count = ARRAY_SIZE(gen9_blt_cmd_table);
                        engine->get_cmd_length_mask =
                                gen9_blt_get_cmd_length_mask;

                        /* BCS Engine unsafe without parser */
                        engine->flags |= I915_ENGINE_REQUIRES_CMD_PARSER;
                } else if (IS_HASWELL(engine->i915)) {
                        cmd_tables = hsw_blt_ring_cmd_table;
                        cmd_table_count = ARRAY_SIZE(hsw_blt_ring_cmd_table);
                } else {
                        cmd_tables = gen7_blt_cmd_table;
                        cmd_table_count = ARRAY_SIZE(gen7_blt_cmd_table);
                }

                if (IS_GEN(engine->i915, 9)) {
                        engine->reg_tables = gen9_blt_reg_tables;
                        engine->reg_table_count =
                                ARRAY_SIZE(gen9_blt_reg_tables);
                } else if (IS_HASWELL(engine->i915)) {
                        engine->reg_tables = hsw_blt_reg_tables;
                        engine->reg_table_count = ARRAY_SIZE(hsw_blt_reg_tables);
                } else {
                        engine->reg_tables = ivb_blt_reg_tables;
                        engine->reg_table_count = ARRAY_SIZE(ivb_blt_reg_tables);
                }
                break;
        case VIDEO_ENHANCEMENT_CLASS:
                cmd_tables = hsw_vebox_cmd_table;
                cmd_table_count = ARRAY_SIZE(hsw_vebox_cmd_table);
                /* VECS can use the same length_mask function as VCS */
                engine->get_cmd_length_mask = gen7_bsd_get_cmd_length_mask;
                break;
        default:
                MISSING_CASE(engine->class);
                return;
        }

        if (!validate_cmds_sorted(engine, cmd_tables, cmd_table_count)) {
                DRM_ERROR("%s: command descriptions are not sorted\n",
                          engine->name);
                return;
        }
        if (!validate_regs_sorted(engine)) {
                DRM_ERROR("%s: registers are not sorted\n", engine->name);
                return;
        }

        ret = init_hash_table(engine, cmd_tables, cmd_table_count);
        if (ret) {
                DRM_ERROR("%s: initialised failed!\n", engine->name);
                fini_hash_table(engine);
                return;
        }

        engine->flags |= I915_ENGINE_USING_CMD_PARSER;
}

/**
 * intel_engine_cleanup_cmd_parser() - clean up cmd parser related fields
 * @engine: the engine to clean up
 *
 * Releases any resources related to command parsing that may have been
 * initialized for the specified engine.
 */
void intel_engine_cleanup_cmd_parser(struct intel_engine_cs *engine)
{
        if (!intel_engine_using_cmd_parser(engine))
                return;

        fini_hash_table(engine);
}

static const struct drm_i915_cmd_descriptor*
find_cmd_in_table(struct intel_engine_cs *engine,
                  u32 cmd_header)
{
        struct cmd_node *desc_node;

        hash_for_each_possible(engine->cmd_hash, desc_node, node,
                               cmd_header_key(cmd_header)) {
                const struct drm_i915_cmd_descriptor *desc = desc_node->desc;
                if (((cmd_header ^ desc->cmd.value) & desc->cmd.mask) == 0)
                        return desc;
        }

        return NULL;
}

/*
 * Returns a pointer to a descriptor for the command specified by cmd_header.
 *
 * The caller must supply space for a default descriptor via the default_desc
 * parameter. If no descriptor for the specified command exists in the engine's
 * command parser tables, this function fills in default_desc based on the
 * engine's default length encoding and returns default_desc.
 */
static const struct drm_i915_cmd_descriptor*
find_cmd(struct intel_engine_cs *engine,
         u32 cmd_header,
         const struct drm_i915_cmd_descriptor *desc,
         struct drm_i915_cmd_descriptor *default_desc)
{
        u32 mask;

        if (((cmd_header ^ desc->cmd.value) & desc->cmd.mask) == 0)
                return desc;

        desc = find_cmd_in_table(engine, cmd_header);
        if (desc)
                return desc;

        mask = engine->get_cmd_length_mask(cmd_header);
        if (!mask)
                return NULL;

        default_desc->cmd.value = cmd_header;
        default_desc->cmd.mask = ~0u << MIN_OPCODE_SHIFT;
        default_desc->length.mask = mask;
        default_desc->flags = CMD_DESC_SKIP;
        return default_desc;
}

static const struct drm_i915_reg_descriptor *
__find_reg(const struct drm_i915_reg_descriptor *table, int count, u32 addr)
{
        int start = 0, end = count;
        while (start < end) {
                int mid = start + (end - start) / 2;
                int ret = addr - i915_mmio_reg_offset(table[mid].addr);
                if (ret < 0)
                        end = mid;
                else if (ret > 0)
                        start = mid + 1;
                else
                        return &table[mid];
        }
        return NULL;
}

static const struct drm_i915_reg_descriptor *
find_reg(const struct intel_engine_cs *engine, u32 addr)
{
        const struct drm_i915_reg_table *table = engine->reg_tables;
        const struct drm_i915_reg_descriptor *reg = NULL;
        int count = engine->reg_table_count;

        for (; !reg && (count > 0); ++table, --count)
                reg = __find_reg(table->regs, table->num_regs, addr);

        return reg;
}

/* Returns a vmap'd pointer to dst_obj, which the caller must unmap */
static u32 *copy_batch(struct drm_i915_gem_object *dst_obj,
                       struct drm_i915_gem_object *src_obj,
                       u32 offset, u32 length)
{
        bool needs_clflush;
        void *dst, *src;
        int ret;

        dst = i915_gem_object_pin_map(dst_obj, I915_MAP_FORCE_WB);
        if (IS_ERR(dst))
                return dst;

        ret = i915_gem_object_pin_pages(src_obj);
        if (ret) {
                i915_gem_object_unpin_map(dst_obj);
                return ERR_PTR(ret);
        }

        needs_clflush =
                !(src_obj->cache_coherent & I915_BO_CACHE_COHERENT_FOR_READ);

        src = ERR_PTR(-ENODEV);
        if (needs_clflush && i915_has_memcpy_from_wc()) {
                src = i915_gem_object_pin_map(src_obj, I915_MAP_WC);
                if (!IS_ERR(src)) {
                        i915_unaligned_memcpy_from_wc(dst,
                                                      src + offset,
                                                      length);
                        i915_gem_object_unpin_map(src_obj);
                }
        }
        if (IS_ERR(src)) {
                void *ptr;
                int x, n;

                /*
                 * We can avoid clflushing partial cachelines before the write
                 * if we only every write full cache-lines. Since we know that
                 * both the source and destination are in multiples of
                 * PAGE_SIZE, we can simply round up to the next cacheline.
                 * We don't care about copying too much here as we only
                 * validate up to the end of the batch.
                 */
                if (!(dst_obj->cache_coherent & I915_BO_CACHE_COHERENT_FOR_READ))
                        length = round_up(length,
                                          boot_cpu_data.x86_clflush_size);

                ptr = dst;
                x = offset_in_page(offset);
                for (n = offset >> PAGE_SHIFT; length; n++) {
                        int len = min_t(int, length, PAGE_SIZE - x);

                        src = kmap_atomic(i915_gem_object_get_page(src_obj, n));
                        if (needs_clflush)
                                drm_clflush_virt_range(src + x, len);
                        memcpy(ptr, src + x, len);
                        kunmap_atomic(src);

                        ptr += len;
                        length -= len;
                        x = 0;
                }
        }

        i915_gem_object_unpin_pages(src_obj);

        /* dst_obj is returned with vmap pinned */
        return dst;
}

static bool check_cmd(const struct intel_engine_cs *engine,
                      const struct drm_i915_cmd_descriptor *desc,
                      const u32 *cmd, u32 length)
{
        if (desc->flags & CMD_DESC_SKIP)
                return true;

        if (desc->flags & CMD_DESC_REJECT) {
                DRM_DEBUG("CMD: Rejected command: 0x%08X\n", *cmd);
                return false;
        }

        if (desc->flags & CMD_DESC_REGISTER) {
                /*
                 * Get the distance between individual register offset
                 * fields if the command can perform more than one
                 * access at a time.
                 */
                const u32 step = desc->reg.step ? desc->reg.step : length;
                u32 offset;

                for (offset = desc->reg.offset; offset < length;
                     offset += step) {
                        const u32 reg_addr = cmd[offset] & desc->reg.mask;
                        const struct drm_i915_reg_descriptor *reg =
                                find_reg(engine, reg_addr);

                        if (!reg) {
                                DRM_DEBUG("CMD: Rejected register 0x%08X in command: 0x%08X (%s)\n",
                                          reg_addr, *cmd, engine->name);
                                return false;
                        }

                        /*
                         * Check the value written to the register against the
                         * allowed mask/value pair given in the whitelist entry.
                         */
                        if (reg->mask) {
                                if (desc->cmd.value == MI_LOAD_REGISTER_MEM) {
                                        DRM_DEBUG("CMD: Rejected LRM to masked register 0x%08X\n",
                                                  reg_addr);
                                        return false;
                                }

                                if (desc->cmd.value == MI_LOAD_REGISTER_REG) {
                                        DRM_DEBUG("CMD: Rejected LRR to masked register 0x%08X\n",
                                                  reg_addr);
                                        return false;
                                }

                                if (desc->cmd.value == MI_LOAD_REGISTER_IMM(1) &&
                                    (offset + 2 > length ||
                                     (cmd[offset + 1] & reg->mask) != reg->value)) {
                                        DRM_DEBUG("CMD: Rejected LRI to masked register 0x%08X\n",
                                                  reg_addr);
                                        return false;
                                }
                        }
                }
        }

        if (desc->flags & CMD_DESC_BITMASK) {
                int i;

                for (i = 0; i < MAX_CMD_DESC_BITMASKS; i++) {
                        u32 dword;

                        if (desc->bits[i].mask == 0)
                                break;

                        if (desc->bits[i].condition_mask != 0) {
                                u32 offset =
                                        desc->bits[i].condition_offset;
                                u32 condition = cmd[offset] &
                                        desc->bits[i].condition_mask;

                                if (condition == 0)
                                        continue;
                        }

                        if (desc->bits[i].offset >= length) {
                                DRM_DEBUG("CMD: Rejected command 0x%08X, too short to check bitmask (%s)\n",
                                          *cmd, engine->name);
                                return false;
                        }

                        dword = cmd[desc->bits[i].offset] &
                                desc->bits[i].mask;

                        if (dword != desc->bits[i].expected) {
                                DRM_DEBUG("CMD: Rejected command 0x%08X for bitmask 0x%08X (exp=0x%08X act=0x%08X) (%s)\n",
                                          *cmd,
                                          desc->bits[i].mask,
                                          desc->bits[i].expected,
                                          dword, engine->name);
                                return false;
                        }
                }
        }

        return true;
}

static int check_bbstart(u32 *cmd, u32 offset, u32 length,
                         u32 batch_length,
                         u64 batch_addr,
                         u64 shadow_addr,
                         const unsigned long *jump_whitelist)
{
        u64 jump_offset, jump_target;
        u32 target_cmd_offset, target_cmd_index;

        /* For igt compatibility on older platforms */
        if (!jump_whitelist) {
                DRM_DEBUG("CMD: Rejecting BB_START for ggtt based submission\n");
                return -EACCES;
        }

        if (length != 3) {
                DRM_DEBUG("CMD: Recursive BB_START with bad length(%u)\n",
                          length);
                return -EINVAL;
        }

        jump_target = *(u64 *)(cmd + 1);
        jump_offset = jump_target - batch_addr;

        /*
         * Any underflow of jump_target is guaranteed to be outside the range
         * of a u32, so >= test catches both too large and too small
         */
        if (jump_offset >= batch_length) {
                DRM_DEBUG("CMD: BB_START to 0x%llx jumps out of BB\n",
                          jump_target);
                return -EINVAL;
        }

        /*
         * This cannot overflow a u32 because we already checked jump_offset
         * is within the BB, and the batch_length is a u32
         */
        target_cmd_offset = lower_32_bits(jump_offset);
        target_cmd_index = target_cmd_offset / sizeof(u32);

        *(u64 *)(cmd + 1) = shadow_addr + target_cmd_offset;

        if (target_cmd_index == offset)
                return 0;

        if (IS_ERR(jump_whitelist))
                return PTR_ERR(jump_whitelist);

        if (!test_bit(target_cmd_index, jump_whitelist)) {
                DRM_DEBUG("CMD: BB_START to 0x%llx not a previously executed cmd\n",
                          jump_target);
                return -EINVAL;
        }

        return 0;
}

static unsigned long *alloc_whitelist(u32 batch_length)
{
        unsigned long *jmp;

        /*
         * We expect batch_length to be less than 256KiB for known users,
         * i.e. we need at most an 8KiB bitmap allocation which should be
         * reasonably cheap due to kmalloc caches.
         */

        /* Prefer to report transient allocation failure rather than hit oom */
        jmp = bitmap_zalloc(DIV_ROUND_UP(batch_length, sizeof(u32)),
                            GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
        if (!jmp)
                return ERR_PTR(-ENOMEM);

        return jmp;
}

#define LENGTH_BIAS 2

static bool shadow_needs_clflush(struct drm_i915_gem_object *obj)
{
        return !(obj->cache_coherent & I915_BO_CACHE_COHERENT_FOR_WRITE);
}

/**
 * intel_engine_cmd_parser() - parse a batch buffer for privilege violations
 * @engine: the engine on which the batch is to execute
 * @batch: the batch buffer in question
 * @batch_offset: byte offset in the batch at which execution starts
 * @batch_length: length of the commands in batch_obj
 * @shadow: validated copy of the batch buffer in question
 * @trampoline: whether to emit a conditional trampoline at the end of the batch
 *
 * Parses the specified batch buffer looking for privilege violations as
 * described in the overview.
 *
 * Return: non-zero if the parser finds violations or otherwise fails; -EACCES
 * if the batch appears legal but should use hardware parsing
 */
int intel_engine_cmd_parser(struct intel_engine_cs *engine,
                            struct i915_vma *batch,
                            u32 batch_offset,
                            u32 batch_length,
                            struct i915_vma *shadow,
                            bool trampoline)
{
        u32 *cmd, *batch_end, offset = 0;
        struct drm_i915_cmd_descriptor default_desc = noop_desc;
        const struct drm_i915_cmd_descriptor *desc = &default_desc;
        unsigned long *jump_whitelist;
        u64 batch_addr, shadow_addr;
        int ret = 0;

        GEM_BUG_ON(!IS_ALIGNED(batch_offset, sizeof(*cmd)));
        GEM_BUG_ON(!IS_ALIGNED(batch_length, sizeof(*cmd)));
        GEM_BUG_ON(range_overflows_t(u64, batch_offset, batch_length,
                                     batch->size));
        GEM_BUG_ON(!batch_length);

        cmd = copy_batch(shadow->obj, batch->obj, batch_offset, batch_length);
        if (IS_ERR(cmd)) {
                DRM_DEBUG("CMD: Failed to copy batch\n");
                return PTR_ERR(cmd);
        }

        jump_whitelist = NULL;
        if (!trampoline)
                /* Defer failure until attempted use */
                jump_whitelist = alloc_whitelist(batch_length);

        shadow_addr = gen8_canonical_addr(shadow->node.start);
        batch_addr = gen8_canonical_addr(batch->node.start + batch_offset);

        /*
         * We use the batch length as size because the shadow object is as
         * large or larger and copy_batch() will write MI_NOPs to the extra
         * space. Parsing should be faster in some cases this way.
         */
        batch_end = cmd + batch_length / sizeof(*batch_end);
        do {
                u32 length;

                if (*cmd == MI_BATCH_BUFFER_END)
                        break;

                desc = find_cmd(engine, *cmd, desc, &default_desc);
                if (!desc) {
                        DRM_DEBUG("CMD: Unrecognized command: 0x%08X\n", *cmd);
                        ret = -EINVAL;
                        break;
                }

                if (desc->flags & CMD_DESC_FIXED)
                        length = desc->length.fixed;
                else
                        length = (*cmd & desc->length.mask) + LENGTH_BIAS;

                if ((batch_end - cmd) < length) {
                        DRM_DEBUG("CMD: Command length exceeds batch length: 0x%08X length=%u batchlen=%td\n",
                                  *cmd,
                                  length,
                                  batch_end - cmd);
                        ret = -EINVAL;
                        break;
                }

                if (!check_cmd(engine, desc, cmd, length)) {
                        ret = -EACCES;
                        break;
                }

                if (desc->cmd.value == MI_BATCH_BUFFER_START) {
                        ret = check_bbstart(cmd, offset, length, batch_length,
                                            batch_addr, shadow_addr,
                                            jump_whitelist);
                        break;
                }

                if (!IS_ERR_OR_NULL(jump_whitelist))
                        __set_bit(offset, jump_whitelist);

                cmd += length;
                offset += length;
                if  (cmd >= batch_end) {
                        DRM_DEBUG("CMD: Got to the end of the buffer w/o a BBE cmd!\n");
                        ret = -EINVAL;
                        break;
                }
        } while (1);

        if (trampoline) {
                /*
                 * With the trampoline, the shadow is executed twice.
                 *
                 *   1 - starting at offset 0, in privileged mode
                 *   2 - starting at offset batch_len, as non-privileged
                 *
                 * Only if the batch is valid and safe to execute, do we
                 * allow the first privileged execution to proceed. If not,
                 * we terminate the first batch and use the second batchbuffer
                 * entry to chain to the original unsafe non-privileged batch,
                 * leaving it to the HW to validate.
                 */
                *batch_end = MI_BATCH_BUFFER_END;

                if (ret) {
                        /* Batch unsafe to execute with privileges, cancel! */
                        cmd = page_mask_bits(shadow->obj->mm.mapping);
                        *cmd = MI_BATCH_BUFFER_END;

                        /* If batch is unsafe but valid, jump to the original */
                        if (ret == -EACCES) {
                                unsigned int flags;

                                flags = MI_BATCH_NON_SECURE_I965;
                                if (IS_HASWELL(engine->i915))
                                        flags = MI_BATCH_NON_SECURE_HSW;

                                GEM_BUG_ON(!IS_GEN_RANGE(engine->i915, 6, 7));
                                __gen6_emit_bb_start(batch_end,
                                                     batch_addr,
                                                     flags);

                                ret = 0; /* allow execution */
                        }
                }

                if (shadow_needs_clflush(shadow->obj))
                        drm_clflush_virt_range(batch_end, 8);
        }

        if (shadow_needs_clflush(shadow->obj)) {
                void *ptr = page_mask_bits(shadow->obj->mm.mapping);

                drm_clflush_virt_range(ptr, (void *)(cmd + 1) - ptr);
        }

        if (!IS_ERR_OR_NULL(jump_whitelist))
                kfree(jump_whitelist);
        i915_gem_object_unpin_map(shadow->obj);
        return ret;
}

/**
 * i915_cmd_parser_get_version() - get the cmd parser version number
 * @dev_priv: i915 device private
 *
 * The cmd parser maintains a simple increasing integer version number suitable
 * for passing to userspace clients to determine what operations are permitted.
 *
 * Return: the current version number of the cmd parser
 */
int i915_cmd_parser_get_version(struct drm_i915_private *dev_priv)
{
        struct intel_engine_cs *engine;
        bool active = false;

        /* If the command parser is not enabled, report 0 - unsupported */
        for_each_uabi_engine(engine, dev_priv) {
                if (intel_engine_using_cmd_parser(engine)) {
                        active = true;
                        break;
                }
        }
        if (!active)
                return 0;

        /*
         * Command parser version history
         *
         * 1. Initial version. Checks batches and reports violations, but leaves
         *    hardware parsing enabled (so does not allow new use cases).
         * 2. Allow access to the MI_PREDICATE_SRC0 and
         *    MI_PREDICATE_SRC1 registers.
         * 3. Allow access to the GPGPU_THREADS_DISPATCHED register.
         * 4. L3 atomic chicken bits of HSW_SCRATCH1 and HSW_ROW_CHICKEN3.
         * 5. GPGPU dispatch compute indirect registers.
         * 6. TIMESTAMP register and Haswell CS GPR registers
         * 7. Allow MI_LOAD_REGISTER_REG between whitelisted registers.
         * 8. Don't report cmd_check() failures as EINVAL errors to userspace;
         *    rely on the HW to NOOP disallowed commands as it would without
         *    the parser enabled.
         * 9. Don't whitelist or handle oacontrol specially, as ownership
         *    for oacontrol state is moving to i915-perf.
         * 10. Support for Gen9 BCS Parsing
         */
        return 10;
}