src/lib/cbmem_console.c

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2
   3 #include <console/cbmem_console.h>
   4 #include <console/console.h>
   5 #include <console/uart.h>
   6 #include <cbmem.h>
   7 #include <symbols.h>
   8 #include <types.h>
   9
  10 /*
  11  * Structure describing console buffer. It is overlaid on a flat memory area,
  12  * with body covering the extent of the memory. Once the buffer is full,
  13  * output will wrap back around to the start of the buffer. The high bit of the
  14  * cursor field gets set to indicate that this happened. If the underlying
  15  * storage allows this, the buffer will persist across multiple boots and append
  16  * to the previous log.
  17  *
  18  * NOTE: These are known implementations accessing this console that need to be
  19  * updated in case of structure/API changes:
  20  *
  21  * cbmem:       [coreboot]/src/util/cbmem/cbmem.c
  22  * libpayload:  [coreboot]/payloads/libpayload/drivers/cbmem_console.c
  23  * coreinfo:    [coreboot]/payloads/coreinfo/bootlog_module.c
  24  * Linux:       drivers/firmware/google/memconsole-coreboot.c
  25  * SeaBIOS:     src/firmware/coreboot.c
  26  * GRUB:        grub-core/term/i386/coreboot/cbmemc.c
  27  */
  28 struct cbmem_console {
  29         u32 size;
  30         u32 cursor;
  31         u8  body[];
  32 }  __packed;
  33
  34 #define MAX_SIZE (1 << 28)      /* can't be changed without breaking readers! */
  35 #define CURSOR_MASK (MAX_SIZE - 1)      /* bits 31-28 are reserved for flags */
  36 #define OVERFLOW (1UL << 31)            /* set if in ring-buffer mode */
  37 _Static_assert(CONFIG_CONSOLE_CBMEM_BUFFER_SIZE <= MAX_SIZE,
  38         "cbmem_console format cannot support buffers larger than 256MB!");
  39
  40 static struct cbmem_console *current_console;
  41
  42 static bool console_paused;
  43
  44 /*
  45  * While running from ROM, before DRAM is initialized, some area in cache as
  46  * RAM space is used for the console buffer storage. The size and location of
  47  * the area are defined by the linker script with _(e)preram_cbmem_console.
  48  *
  49  * When running from RAM, some console output is generated before CBMEM is
  50  * reinitialized. This static buffer is used to store that output temporarily,
  51  * to be concatenated with the CBMEM console buffer contents accumulated
  52  * during the ROM stage, once CBMEM becomes available at RAM stage.
  53  */
  54
  55 #define STATIC_CONSOLE_SIZE 1024
  56 static u8 static_console[STATIC_CONSOLE_SIZE];
  57
  58 static int buffer_valid(struct cbmem_console *cbm_cons_p, u32 total_space)
  59 {
  60         return (cbm_cons_p->cursor & CURSOR_MASK) < cbm_cons_p->size &&
  61                cbm_cons_p->size <= MAX_SIZE &&
  62                cbm_cons_p->size == total_space - sizeof(struct cbmem_console);
  63 }
  64
  65 static void init_console_ptr(void *storage, u32 total_space)
  66 {
  67         struct cbmem_console *cbm_cons_p = storage;
  68
  69         if (!cbm_cons_p || total_space <= sizeof(struct cbmem_console)) {
  70                 current_console = NULL;
  71                 return;
  72         }
  73
  74         if (!buffer_valid(cbm_cons_p, total_space)) {
  75                 cbm_cons_p->size = total_space - sizeof(struct cbmem_console);
  76                 cbm_cons_p->cursor = 0;
  77         }
  78
  79         current_console = cbm_cons_p;
  80 }
  81
  82 void cbmemc_init(void)
  83 {
  84         if (ENV_ROMSTAGE_OR_BEFORE) {
  85                 /* Pre-RAM environments use special buffer placed by linker script. */
  86                 init_console_ptr(_preram_cbmem_console, REGION_SIZE(preram_cbmem_console));
  87         } else if (ENV_SMM) {
  88                 void *cbmemc = NULL;
  89                 size_t cbmemc_size = 0;
  90
  91                 smm_get_cbmemc_buffer(&cbmemc, &cbmemc_size);
  92
  93                 init_console_ptr(cbmemc, cbmemc_size);
  94         } else {
  95                 /* Post-RAM uses static (BSS) buffer before CBMEM is reinitialized. */
  96                 init_console_ptr(static_console, sizeof(static_console));
  97         }
  98 }
  99
 100 void cbmemc_tx_byte(unsigned char data)
 101 {
 102         if (!current_console || !current_console->size || console_paused)
 103                 return;
 104
 105         u32 flags = current_console->cursor & ~CURSOR_MASK;
 106         u32 cursor = current_console->cursor & CURSOR_MASK;
 107
 108         current_console->body[cursor++] = data;
 109         if (cursor >= current_console->size) {
 110                 cursor = 0;
 111                 flags |= OVERFLOW;
 112         }
 113
 114         current_console->cursor = flags | cursor;
 115 }
 116
 117 /*
 118  * Copy the current console buffer (either from the cache as RAM area or from
 119  * the static buffer, pointed at by src_cons_p) into the newly initialized CBMEM
 120  * console. The use of cbmemc_tx_byte() ensures that all special cases for the
 121  * target console (e.g. overflow) will be handled. If there had been an
 122  * overflow in the source console, log a message to that effect.
 123  */
 124 static void copy_console_buffer(struct cbmem_console *src_cons_p)
 125 {
 126         u32 c;
 127
 128         if (!src_cons_p)
 129                 return;
 130
 131         if (src_cons_p->cursor & OVERFLOW) {
 132                 const char overflow_warning[] = "\n*** Pre-CBMEM " ENV_STRING
 133                         " console overflowed, log truncated! ***\n";
 134                 for (c = 0; c < sizeof(overflow_warning) - 1; c++)
 135                         cbmemc_tx_byte(overflow_warning[c]);
 136                 for (c = src_cons_p->cursor & CURSOR_MASK;
 137                      c < src_cons_p->size; c++)
 138                         cbmemc_tx_byte(src_cons_p->body[c]);
 139         }
 140
 141         for (c = 0; c < (src_cons_p->cursor & CURSOR_MASK); c++)
 142                 cbmemc_tx_byte(src_cons_p->body[c]);
 143
 144         /* Invalidate the source console, so it will be reinitialized on the
 145            next reboot. Otherwise, we might copy the same bytes again. */
 146         src_cons_p->size = 0;
 147 }
 148
 149 void cbmemc_copy_in(void *buffer, size_t size)
 150 {
 151         struct cbmem_console *previous = (void *)buffer;
 152
 153         if (!buffer_valid(previous, size))
 154                 return;
 155
 156         copy_console_buffer(previous);
 157 }
 158
 159 static void cbmemc_reinit(int is_recovery)
 160 {
 161         const size_t size = CONFIG_CONSOLE_CBMEM_BUFFER_SIZE;
 162         /* If CBMEM entry already existed, old contents are not altered. */
 163         struct cbmem_console *cbmem_cons_p = cbmem_add(CBMEM_ID_CONSOLE, size);
 164         struct cbmem_console *previous_cons_p = current_console;
 165
 166         init_console_ptr(cbmem_cons_p, size);
 167         copy_console_buffer(previous_cons_p);
 168 }
 169
 170 /* Run this hook early so that the console region is one of the earliest created, and
 171    therefore more likely to stay in the same place even across different boot modes where some
 172    other regions may sometimes not get created (e.g. RW_MCACHE in vboot recovery mode). */
 173 CBMEM_READY_HOOK_EARLY(cbmemc_reinit);
 174
 175 #if CONFIG(CONSOLE_CBMEM_DUMP_TO_UART)
 176 void cbmem_dump_console_to_uart(void)
 177 {
 178         u32 cursor;
 179         unsigned int console_index;
 180
 181         if (!current_console)
 182                 return;
 183
 184         console_index = get_uart_for_console();
 185
 186         uart_init(console_index);
 187         if (current_console->cursor & OVERFLOW) {
 188                 for (cursor = current_console->cursor & CURSOR_MASK;
 189                      cursor < current_console->size; cursor++) {
 190                         if (BIOS_LOG_IS_MARKER(current_console->body[cursor]))
 191                                 continue;
 192                         if (current_console->body[cursor] == '\n')
 193                                 uart_tx_byte(console_index, '\r');
 194                         uart_tx_byte(console_index, current_console->body[cursor]);
 195                 }
 196         }
 197         for (cursor = 0; cursor < (current_console->cursor & CURSOR_MASK); cursor++) {
 198                 if (BIOS_LOG_IS_MARKER(current_console->body[cursor]))
 199                         continue;
 200                 if (current_console->body[cursor] == '\n')
 201                         uart_tx_byte(console_index, '\r');
 202                 uart_tx_byte(console_index, current_console->body[cursor]);
 203         }
 204 }
 205 #endif
 206
 207 void cbmem_dump_console(void)
 208 {
 209         u32 cursor;
 210         if (!current_console)
 211                 return;
 212
 213         console_paused = true;
 214
 215         if (current_console->cursor & OVERFLOW)
 216                 for (cursor = current_console->cursor & CURSOR_MASK;
 217                      cursor < current_console->size; cursor++)
 218                         if (!BIOS_LOG_IS_MARKER(current_console->body[cursor]))
 219                                 do_putchar(current_console->body[cursor]);
 220         for (cursor = 0; cursor < (current_console->cursor & CURSOR_MASK); cursor++)
 221                 if (!BIOS_LOG_IS_MARKER(current_console->body[cursor]))
 222                         do_putchar(current_console->body[cursor]);
 223
 224         console_paused = false;
 225 }