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x86: Load __USER_DS into DS/ES after resume

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Srinivas Pandruvada reported a problem with system resume from
suspend-to-RAM on 32-bit x86 systems where the DS register of
the CPU is set to __KERNEL_DS instead of __USER_DS on return
to user space which cases a General Protection Fault to occur.

The issue is that DS is set to __KERNEL_DS by the ACPI resume code
path while the SYSEXIT path never reloads DS/ES.  It assumes they
are still __USER_DS set at the SYSENTER time (Brian Gerst), so if
the return to user space happens to be through SYSEXIT, it will lead
to the reported GPF.

Fix the problem by setting the DS and ES registers to __USER_DS
as expected by the SYSEXIT path.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=61781
Link: http://marc.info/?l=linux-pm&m=143406648920385&w=2
Acked-by: Pavel Machek <pavel@ucw.cz>
Tested-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Ingo Molnar <mingo@kernel.org>

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Ingo Molnar 2015-06-22 14:40:03 +02:00 committed by Rafael J. Wysocki
parent 32e8d689dc
commit ffa64eff95
1 changed files with 4 additions and 2 deletions
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6
arch/x86/kernel/acpi/wakeup_32.S
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@ -12,11 +12,13 @@ ENTRY(wakeup_pmode_return)
wakeup_pmode_return:
movw $__KERNEL_DS, %ax
movw %ax, %ss
movw %ax, %ds
movw %ax, %es
movw %ax, %fs
movw %ax, %gs
movw $__USER_DS, %ax
movw %ax, %ds
movw %ax, %es
# reload the gdt, as we need the full 32 bit address
lidt saved_idt
lldt saved_ldt