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| author | Christophe Leroy <christophe.leroy@csgroup.eu> | 2021-02-08 10:17:40 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-02-11 15:35:06 +0300 |
| commit | 3642eb21256a317ac14e9ed560242c6d20cf06d9 (patch) | |
| tree | 18a9f2dadd82a25984d362d058bdf7ef7cc0f5e0 /arch/powerpc | |
| parent | ac7c5e9b08acdb54ef3525abcad24bdb3ed05551 (diff) | |
| download | linux-3642eb21256a317ac14e9ed560242c6d20cf06d9.tar.xz | |
powerpc/32: Preserve cr1 in exception prolog stack check to fix build error
THREAD_ALIGN_SHIFT = THREAD_SHIFT + 1 = PAGE_SHIFT + 1
Maximum PAGE_SHIFT is 18 for 256k pages so
THREAD_ALIGN_SHIFT is 19 at the maximum.
No need to clobber cr1, it can be preserved when moving r1
into CR when we check stack overflow.
This reduces the number of instructions in Machine Check Exception
prolog and fixes a build failure reported by the kernel test robot
on v5.10 stable when building with RTAS + VMAP_STACK + KVM. That
build failure is due to too many instructions in the prolog hence
not fitting between 0x200 and 0x300. Allthough the problem doesn't
show up in mainline, it is still worth the change.
Fixes: 98bf2d3f4970 ("powerpc/32s: Fix RTAS machine check with VMAP stack")
Cc: stable@vger.kernel.org
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/5ae4d545e3ac58e133d2599e0deb88843cb494fc.1612768623.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/kernel/head_32.h | 2 | ||||
| -rw-r--r-- | arch/powerpc/kernel/head_book3s_32.S | 6 |
2 files changed, 1 insertions, 7 deletions
diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h index a2f72c966baf..abc7b603ab65 100644 --- a/arch/powerpc/kernel/head_32.h +++ b/arch/powerpc/kernel/head_32.h @@ -47,7 +47,7 @@ lwz r1,TASK_STACK-THREAD(r1) addi r1, r1, THREAD_SIZE - INT_FRAME_SIZE 1: - mtcrf 0x7f, r1 + mtcrf 0x3f, r1 bt 32 - THREAD_ALIGN_SHIFT, stack_overflow #else subi r11, r1, INT_FRAME_SIZE /* use r1 if kernel */ diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S index 1b9c62423b09..a4eaf214e112 100644 --- a/arch/powerpc/kernel/head_book3s_32.S +++ b/arch/powerpc/kernel/head_book3s_32.S @@ -269,12 +269,6 @@ MachineCheck: 7: EXCEPTION_PROLOG_2 addi r3,r1,STACK_FRAME_OVERHEAD #ifdef CONFIG_PPC_CHRP -#ifdef CONFIG_VMAP_STACK - mfspr r4, SPRN_SPRG_THREAD - tovirt(r4, r4) - lwz r4, RTAS_SP(r4) - cmpwi cr1, r4, 0 -#endif beq cr1, machine_check_tramp twi 31, 0, 0 #else |