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powerpc/powernv/idle: Restore AMR/UAMOR/AMOR after idle

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commit 53a712bae5dd919521a58d7bad773b949358add0 upstream.

In order to implement KUAP (Kernel Userspace Access Protection) on
Power9 we will be using the AMR, and therefore indirectly the
UAMOR/AMOR.

So save/restore these regs in the idle code.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
[ajd: Backport to 4.14 tree, CVE-2020-11669]
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Michael Ellerman 2019-04-18 16:51:17 +10:00 committed by Greg Kroah-Hartman
parent 5a294c1f8b
commit 66a93f5733
1 changed files with 23 additions and 4 deletions
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27
arch/powerpc/kernel/idle_book3s.S
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@ -163,8 +163,11 @@ core_idle_lock_held:
bne- core_idle_lock_held
blr
/* Reuse an unused pt_regs slot for IAMR */
/* Reuse some unused pt_regs slots for AMR/IAMR/UAMOR/UAMOR */
#define PNV_POWERSAVE_AMR _TRAP
#define PNV_POWERSAVE_IAMR _DAR
#define PNV_POWERSAVE_UAMOR _DSISR
#define PNV_POWERSAVE_AMOR RESULT
/*
* Pass requested state in r3:
@ -198,8 +201,16 @@ pnv_powersave_common:
SAVE_NVGPRS(r1)
BEGIN_FTR_SECTION
mfspr r4, SPRN_AMR
mfspr r5, SPRN_IAMR
mfspr r6, SPRN_UAMOR
std r4, PNV_POWERSAVE_AMR(r1)
std r5, PNV_POWERSAVE_IAMR(r1)
std r6, PNV_POWERSAVE_UAMOR(r1)
BEGIN_FTR_SECTION_NESTED(42)
mfspr r7, SPRN_AMOR
std r7, PNV_POWERSAVE_AMOR(r1)
END_FTR_SECTION_NESTED_IFSET(CPU_FTR_HVMODE, 42)
END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
mfcr r5
@ -951,12 +962,20 @@ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
REST_GPR(2, r1)
BEGIN_FTR_SECTION
/* IAMR was saved in pnv_powersave_common() */
/* These regs were saved in pnv_powersave_common() */
ld r4, PNV_POWERSAVE_AMR(r1)
ld r5, PNV_POWERSAVE_IAMR(r1)
ld r6, PNV_POWERSAVE_UAMOR(r1)
mtspr SPRN_AMR, r4
mtspr SPRN_IAMR, r5
mtspr SPRN_UAMOR, r6
BEGIN_FTR_SECTION_NESTED(42)
ld r7, PNV_POWERSAVE_AMOR(r1)
mtspr SPRN_AMOR, r7
END_FTR_SECTION_NESTED_IFSET(CPU_FTR_HVMODE, 42)
/*
* We don't need an isync here because the upcoming mtmsrd is
* execution synchronizing.
* We don't need an isync here after restoring IAMR because the upcoming
* mtmsrd is execution synchronizing.
*/
END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)