Hi, The patch below fixes the regression described at http://bugzilla.kernel.org/show_bug.cgi?id=10927 which is caused by the fact that some BIOSes call the kernel's resume code with post-protected mode garbage in segment registers. Apart from Dell laptops referred to in the chagelog it has a potential to fix some other systems on which resume from suspend to RAM fails in a mysterious way and the probability of it breaking things is rather small, so IMO it would be nice to have in 2.6.26. Thanks, Rafael --- From: H. Peter Anvin <hpa@xxxxxxxxx> x86 ACPI: normalize segment descriptor register on resume Some Dell laptops enter resume with apparent garbage in the segment descriptor registers (almost certainly the result of a botched transition from protected to real mode.) The only way to clean that up is to enter protected mode ourselves and clean out the descriptor registers. This fixes resume on Dell XPS M1210 and Dell D620. Reference: http://bugzilla.kernel.org/show_bug.cgi?id=10927 Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxx> Tested-by: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx> Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx> --- arch/x86/kernel/acpi/realmode/wakeup.S | 38 ++++++++++++++++++++++++++++++++- arch/x86/kernel/acpi/realmode/wakeup.h | 5 ++++ arch/x86/kernel/acpi/sleep.c | 16 +++++++++++++ drivers/acpi/sleep/main.c | 5 +--- 4 files changed, 59 insertions(+), 5 deletions(-) Index: linux-2.6/arch/x86/kernel/acpi/realmode/wakeup.S =================================================================== --- linux-2.6.orig/arch/x86/kernel/acpi/realmode/wakeup.S +++ linux-2.6/arch/x86/kernel/acpi/realmode/wakeup.S @@ -5,6 +5,7 @@ #include <asm/msr-index.h> #include <asm/page.h> #include <asm/pgtable.h> +#include <asm/processor-flags.h> .code16 .section ".header", "a" @@ -24,6 +25,11 @@ pmode_gdt: .quad 0 realmode_flags: .long 0 real_magic: .long 0 trampoline_segment: .word 0 +_pad1: .byte 0 +wakeup_jmp: .byte 0xea /* ljmpw */ +wakeup_jmp_off: .word 3f +wakeup_jmp_seg: .word 0 +wakeup_gdt: .quad 0, 0, 0 signature: .long 0x51ee1111 .text @@ -34,11 +40,34 @@ _start: cli cld + /* Apparently some dimwit BIOS programmers don't know how to + program a PM to RM transition, and we might end up here with + junk in the data segment descriptor registers. The only way + to repair that is to go into PM and fix it ourselves... */ + movw $16, %cx + lgdtl %cs:wakeup_gdt + movl %cr0, %eax + orb $X86_CR0_PE, %al + movl %eax, %cr0 + jmp 1f +1: ljmpw $8, $2f +2: + movw %cx, %ds + movw %cx, %es + movw %cx, %ss + movw %cx, %fs + movw %cx, %gs + + andb $~X86_CR0_PE, %al + movl %eax, %cr0 + jmp wakeup_jmp +3: /* Set up segments */ movw %cs, %ax movw %ax, %ds movw %ax, %es movw %ax, %ss + lidtl wakeup_idt movl $wakeup_stack_end, %esp @@ -98,7 +127,14 @@ bogus_real_magic: jmp 1b .data - .balign 4 + .balign 8 + + /* This is the standard real-mode IDT */ +wakeup_idt: + .word 0xffff /* limit */ + .long 0 /* address */ + .word 0 + .globl HEAP, heap_end HEAP: .long wakeup_heap Index: linux-2.6/arch/x86/kernel/acpi/realmode/wakeup.h =================================================================== --- linux-2.6.orig/arch/x86/kernel/acpi/realmode/wakeup.h +++ linux-2.6/arch/x86/kernel/acpi/realmode/wakeup.h @@ -24,6 +24,11 @@ struct wakeup_header { u32 realmode_flags; u32 real_magic; u16 trampoline_segment; /* segment with trampoline code, 64-bit only */ + u8 _pad1; + u8 wakeup_jmp; + u16 wakeup_jmp_off; + u16 wakeup_jmp_seg; + u64 wakeup_gdt[3]; u32 signature; /* To check we have correct structure */ } __attribute__((__packed__)); Index: linux-2.6/arch/x86/kernel/acpi/sleep.c =================================================================== --- linux-2.6.orig/arch/x86/kernel/acpi/sleep.c +++ linux-2.6/arch/x86/kernel/acpi/sleep.c @@ -50,6 +50,20 @@ int acpi_save_state_mem(void) header->video_mode = saved_video_mode; + header->wakeup_jmp_seg = acpi_wakeup_address >> 4; + /* GDT[0]: GDT self-pointer */ + header->wakeup_gdt[0] = + (u64)(sizeof(header->wakeup_gdt) - 1) + + ((u64)(acpi_wakeup_address + + ((char *)&header->wakeup_gdt - (char *)acpi_realmode)) + << 16); + /* GDT[1]: real-mode-like code segment */ + header->wakeup_gdt[1] = (0x009bULL << 40) + + ((u64)acpi_wakeup_address << 16) + 0xffff; + /* GDT[2]: real-mode-like data segment */ + header->wakeup_gdt[2] = (0x0093ULL << 40) + + ((u64)acpi_wakeup_address << 16) + 0xffff; + #ifndef CONFIG_64BIT store_gdt((struct desc_ptr *)&header->pmode_gdt); @@ -111,7 +125,7 @@ void __init acpi_reserve_bootmem(void) return; } - acpi_wakeup_address = acpi_realmode; + acpi_wakeup_address = virt_to_phys((void *)acpi_realmode); } Index: linux-2.6/drivers/acpi/sleep/main.c =================================================================== --- linux-2.6.orig/drivers/acpi/sleep/main.c +++ linux-2.6/drivers/acpi/sleep/main.c @@ -32,9 +32,8 @@ static int acpi_sleep_prepare(u32 acpi_s if (!acpi_wakeup_address) { return -EFAULT; } - acpi_set_firmware_waking_vector((acpi_physical_address) - virt_to_phys((void *) - acpi_wakeup_address)); + acpi_set_firmware_waking_vector( + (acpi_physical_address)acpi_wakeup_address); } ACPI_FLUSH_CPU_CACHE(); _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
