x86, efi: Set runtime_version to the EFI spec revision
[linux/fpc-iii.git] / arch / arm / kernel / swp_emulate.c
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1 /*
2 * linux/arch/arm/kernel/swp_emulate.c
4 * Copyright (C) 2009 ARM Limited
5 * __user_* functions adapted from include/asm/uaccess.h
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
11 * Implements emulation of the SWP/SWPB instructions using load-exclusive and
12 * store-exclusive for processors that have them disabled (or future ones that
13 * might not implement them).
15 * Syntax of SWP{B} instruction: SWP{B}<c> <Rt>, <Rt2>, [<Rn>]
16 * Where: Rt = destination
17 * Rt2 = source
18 * Rn = address
21 #include <linux/init.h>
22 #include <linux/kernel.h>
23 #include <linux/proc_fs.h>
24 #include <linux/sched.h>
25 #include <linux/syscalls.h>
26 #include <linux/perf_event.h>
28 #include <asm/opcodes.h>
29 #include <asm/traps.h>
30 #include <asm/uaccess.h>
33 * Error-checking SWP macros implemented using ldrex{b}/strex{b}
35 #define __user_swpX_asm(data, addr, res, temp, B) \
36 __asm__ __volatile__( \
37 " mov %2, %1\n" \
38 "0: ldrex"B" %1, [%3]\n" \
39 "1: strex"B" %0, %2, [%3]\n" \
40 " cmp %0, #0\n" \
41 " movne %0, %4\n" \
42 "2:\n" \
43 " .section .fixup,\"ax\"\n" \
44 " .align 2\n" \
45 "3: mov %0, %5\n" \
46 " b 2b\n" \
47 " .previous\n" \
48 " .section __ex_table,\"a\"\n" \
49 " .align 3\n" \
50 " .long 0b, 3b\n" \
51 " .long 1b, 3b\n" \
52 " .previous" \
53 : "=&r" (res), "+r" (data), "=&r" (temp) \
54 : "r" (addr), "i" (-EAGAIN), "i" (-EFAULT) \
55 : "cc", "memory")
57 #define __user_swp_asm(data, addr, res, temp) \
58 __user_swpX_asm(data, addr, res, temp, "")
59 #define __user_swpb_asm(data, addr, res, temp) \
60 __user_swpX_asm(data, addr, res, temp, "b")
63 * Macros/defines for extracting register numbers from instruction.
65 #define EXTRACT_REG_NUM(instruction, offset) \
66 (((instruction) & (0xf << (offset))) >> (offset))
67 #define RN_OFFSET 16
68 #define RT_OFFSET 12
69 #define RT2_OFFSET 0
71 * Bit 22 of the instruction encoding distinguishes between
72 * the SWP and SWPB variants (bit set means SWPB).
74 #define TYPE_SWPB (1 << 22)
76 static unsigned long swpcounter;
77 static unsigned long swpbcounter;
78 static unsigned long abtcounter;
79 static pid_t previous_pid;
81 #ifdef CONFIG_PROC_FS
82 static int proc_read_status(char *page, char **start, off_t off, int count,
83 int *eof, void *data)
85 char *p = page;
86 int len;
88 p += sprintf(p, "Emulated SWP:\t\t%lu\n", swpcounter);
89 p += sprintf(p, "Emulated SWPB:\t\t%lu\n", swpbcounter);
90 p += sprintf(p, "Aborted SWP{B}:\t\t%lu\n", abtcounter);
91 if (previous_pid != 0)
92 p += sprintf(p, "Last process:\t\t%d\n", previous_pid);
94 len = (p - page) - off;
95 if (len < 0)
96 len = 0;
98 *eof = (len <= count) ? 1 : 0;
99 *start = page + off;
101 return len;
103 #endif
106 * Set up process info to signal segmentation fault - called on access error.
108 static void set_segfault(struct pt_regs *regs, unsigned long addr)
110 siginfo_t info;
112 down_read(&current->mm->mmap_sem);
113 if (find_vma(current->mm, addr) == NULL)
114 info.si_code = SEGV_MAPERR;
115 else
116 info.si_code = SEGV_ACCERR;
117 up_read(&current->mm->mmap_sem);
119 info.si_signo = SIGSEGV;
120 info.si_errno = 0;
121 info.si_addr = (void *) instruction_pointer(regs);
123 pr_debug("SWP{B} emulation: access caused memory abort!\n");
124 arm_notify_die("Illegal memory access", regs, &info, 0, 0);
126 abtcounter++;
129 static int emulate_swpX(unsigned int address, unsigned int *data,
130 unsigned int type)
132 unsigned int res = 0;
134 if ((type != TYPE_SWPB) && (address & 0x3)) {
135 /* SWP to unaligned address not permitted */
136 pr_debug("SWP instruction on unaligned pointer!\n");
137 return -EFAULT;
140 while (1) {
141 unsigned long temp;
144 * Barrier required between accessing protected resource and
145 * releasing a lock for it. Legacy code might not have done
146 * this, and we cannot determine that this is not the case
147 * being emulated, so insert always.
149 smp_mb();
151 if (type == TYPE_SWPB)
152 __user_swpb_asm(*data, address, res, temp);
153 else
154 __user_swp_asm(*data, address, res, temp);
156 if (likely(res != -EAGAIN) || signal_pending(current))
157 break;
159 cond_resched();
162 if (res == 0) {
164 * Barrier also required between acquiring a lock for a
165 * protected resource and accessing the resource. Inserted for
166 * same reason as above.
168 smp_mb();
170 if (type == TYPE_SWPB)
171 swpbcounter++;
172 else
173 swpcounter++;
176 return res;
180 * swp_handler logs the id of calling process, dissects the instruction, sanity
181 * checks the memory location, calls emulate_swpX for the actual operation and
182 * deals with fixup/error handling before returning
184 static int swp_handler(struct pt_regs *regs, unsigned int instr)
186 unsigned int address, destreg, data, type;
187 unsigned int res = 0;
189 perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, regs, regs->ARM_pc);
191 res = arm_check_condition(instr, regs->ARM_cpsr);
192 switch (res) {
193 case ARM_OPCODE_CONDTEST_PASS:
194 break;
195 case ARM_OPCODE_CONDTEST_FAIL:
196 /* Condition failed - return to next instruction */
197 regs->ARM_pc += 4;
198 return 0;
199 case ARM_OPCODE_CONDTEST_UNCOND:
200 /* If unconditional encoding - not a SWP, undef */
201 return -EFAULT;
202 default:
203 return -EINVAL;
206 if (current->pid != previous_pid) {
207 pr_debug("\"%s\" (%ld) uses deprecated SWP{B} instruction\n",
208 current->comm, (unsigned long)current->pid);
209 previous_pid = current->pid;
212 address = regs->uregs[EXTRACT_REG_NUM(instr, RN_OFFSET)];
213 data = regs->uregs[EXTRACT_REG_NUM(instr, RT2_OFFSET)];
214 destreg = EXTRACT_REG_NUM(instr, RT_OFFSET);
216 type = instr & TYPE_SWPB;
218 pr_debug("addr in r%d->0x%08x, dest is r%d, source in r%d->0x%08x)\n",
219 EXTRACT_REG_NUM(instr, RN_OFFSET), address,
220 destreg, EXTRACT_REG_NUM(instr, RT2_OFFSET), data);
222 /* Check access in reasonable access range for both SWP and SWPB */
223 if (!access_ok(VERIFY_WRITE, (address & ~3), 4)) {
224 pr_debug("SWP{B} emulation: access to %p not allowed!\n",
225 (void *)address);
226 res = -EFAULT;
227 } else {
228 res = emulate_swpX(address, &data, type);
231 if (res == 0) {
233 * On successful emulation, revert the adjustment to the PC
234 * made in kernel/traps.c in order to resume execution at the
235 * instruction following the SWP{B}.
237 regs->ARM_pc += 4;
238 regs->uregs[destreg] = data;
239 } else if (res == -EFAULT) {
241 * Memory errors do not mean emulation failed.
242 * Set up signal info to return SEGV, then return OK
244 set_segfault(regs, address);
247 return 0;
251 * Only emulate SWP/SWPB executed in ARM state/User mode.
252 * The kernel must be SWP free and SWP{B} does not exist in Thumb/ThumbEE.
254 static struct undef_hook swp_hook = {
255 .instr_mask = 0x0fb00ff0,
256 .instr_val = 0x01000090,
257 .cpsr_mask = MODE_MASK | PSR_T_BIT | PSR_J_BIT,
258 .cpsr_val = USR_MODE,
259 .fn = swp_handler
263 * Register handler and create status file in /proc/cpu
264 * Invoked as late_initcall, since not needed before init spawned.
266 static int __init swp_emulation_init(void)
268 #ifdef CONFIG_PROC_FS
269 struct proc_dir_entry *res;
271 res = create_proc_entry("cpu/swp_emulation", S_IRUGO, NULL);
273 if (!res)
274 return -ENOMEM;
276 res->read_proc = proc_read_status;
277 #endif /* CONFIG_PROC_FS */
279 printk(KERN_NOTICE "Registering SWP/SWPB emulation handler\n");
280 register_undef_hook(&swp_hook);
282 return 0;
285 late_initcall(swp_emulation_init);