From: Michael Ellerman mpe@ellerman.id.au
mainline inclusion from mainline-v5.2-rc1 commit 53a712bae5dd919521a58d7bad773b949358add0 category: bugfix bugzilla: 13690 CVE: CVE-2020-11669
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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 Signed-off-by: Yang Yingliang yangyingliang@huawei.com Reviewed-by: Jason Yan yanaijie@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- arch/powerpc/kernel/idle_book3s.S | 27 +++++++++++++++++++++++---- 1 file changed, 23 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S index 3617800..4a860d3 100644 --- a/arch/powerpc/kernel/idle_book3s.S +++ b/arch/powerpc/kernel/idle_book3s.S @@ -170,8 +170,11 @@ 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: @@ -205,8 +208,16 @@ 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 @@ -935,12 +946,20 @@ 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)