diff options
Diffstat (limited to 'arch/x86/lib/acpi_s3.c')
| -rw-r--r-- | arch/x86/lib/acpi_s3.c | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/arch/x86/lib/acpi_s3.c b/arch/x86/lib/acpi_s3.c index 0b62b75..3175da8 100644 --- a/arch/x86/lib/acpi_s3.c +++ b/arch/x86/lib/acpi_s3.c @@ -9,6 +9,8 @@ #include <asm/acpi_table.h> #include <asm/post.h> +DECLARE_GLOBAL_DATA_PTR; + static void asmlinkage (*acpi_do_wakeup)(void *vector) = (void *)WAKEUP_BASE; static void acpi_jump_to_wakeup(void *vector) @@ -29,6 +31,52 @@ void acpi_resume(struct acpi_fadt *fadt) wake_vec = acpi_find_wakeup_vector(fadt); + /* + * Restore the memory content starting from address 0x1000 which is + * used for the real mode interrupt handler stubs. + */ + memcpy((void *)0x1000, (const void *)gd->arch.backup_mem, + S3_RESERVE_SIZE); + post_code(POST_OS_RESUME); acpi_jump_to_wakeup(wake_vec); } + +int acpi_s3_reserve(void) +{ + /* adjust stack pointer for ACPI S3 resume backup memory */ + gd->start_addr_sp -= S3_RESERVE_SIZE; + gd->arch.backup_mem = gd->start_addr_sp; + + gd->start_addr_sp &= ~0xf; + + /* + * U-Boot sets up the real mode interrupt handler stubs starting from + * address 0x1000. In most cases, the first 640K (0x00000 - 0x9ffff) + * system memory is reported as system RAM in E820 table to the OS. + * (see install_e820_map() implementation for each platform). So OS + * can use these memories whatever it wants. + * + * If U-Boot is in an S3 resume path, care must be taken not to corrupt + * these memorie otherwise OS data gets lost. Testing shows that, on + * Microsoft Windows 10 on Intel Baytrail its wake up vector happens to + * be installed at the same address 0x1000. While on Linux its wake up + * vector does not overlap this memory range, but after resume kernel + * checks low memory range per config option CONFIG_X86_RESERVE_LOW + * which is 64K by default to see whether a memory corruption occurs + * during the suspend/resume (it's harmless, but warnings are shown + * in the kernel dmesg logs). + * + * We cannot simply mark the these memory as reserved in E820 table + * because such configuration makes GRUB complain: unable to allocate + * real mode page. Hence we choose to back up these memories to the + * place where we reserved on our stack for our S3 resume work. + * Before jumping to OS wake up vector, we need restore the original + * content there (see acpi_resume() above). + */ + if (gd->arch.prev_sleep_state == ACPI_S3) + memcpy((void *)gd->arch.backup_mem, (const void *)0x1000, + S3_RESERVE_SIZE); + + return 0; +} |