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@zytor.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: pm list <linux-pm@lists.linux-foundation.org>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/kernel/acpi/realmode/wakeup.S b/arch/x86/kernel/acpi/realmode/wakeup.S
index f9b77fb..3355973 100644 (file)
--- a/arch/x86/kernel/acpi/realmode/wakeup.S
+++ b/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

diff --git a/arch/x86/kernel/acpi/realmode/wakeup.h b/arch/x86/kernel/acpi/realmode/wakeup.h
index ef8166f..69d38d0 100644 (file)
--- a/arch/x86/kernel/acpi/realmode/wakeup.h
+++ b/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__));
 

diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
index afc25ee..36af01f 100644 (file)
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/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);
 }
 
 

diff --git a/drivers/acpi/sleep/main.c b/drivers/acpi/sleep/main.c
index c3b0cd8..495c63a 100644 (file)
--- a/drivers/acpi/sleep/main.c
+++ b/drivers/acpi/sleep/main.c
@@ -36,9 +36,8 @@ static int acpi_sleep_prepare(u32 acpi_state)
                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();