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powerpc/64s: Remove EXSLB interrupt save area

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SLB faults should not be taken while the PACA save areas are live, all
memory accesses should be fetches from the kernel text, and access to
PACA and the current stack, before C code is called or any other
accesses are made.

All of these have pinned SLBs so will not take a SLB fault. Therefore
EXSLB is not be required.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210208063406.331655-1-npiggin@gmail.com
This commit is contained in:
Nicholas Piggin 2021-02-08 16:34:06 +10:00 committed by Michael Ellerman
parent 14ad0e7d04
commit ac7c5e9b08
3 changed files with 1 additions and 8 deletions
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3
arch/powerpc/include/asm/paca.h
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@ -109,8 +109,7 @@ struct paca_struct {
*/
/* used for most interrupts/exceptions */
u64 exgen[EX_SIZE] __attribute__((aligned(0x80)));
u64 exslb[EX_SIZE]; /* used for SLB/segment table misses
* on the linear mapping */
/* SLB related definitions */
u16 vmalloc_sllp;
u8 slb_cache_ptr;

1
arch/powerpc/kernel/asm-offsets.c
View File

@ -255,7 +255,6 @@ int main(void)
#endif /* CONFIG_PPC_MM_SLICES */
OFFSET(PACA_EXGEN, paca_struct, exgen);
OFFSET(PACA_EXMC, paca_struct, exmc);
OFFSET(PACA_EXSLB, paca_struct, exslb);
OFFSET(PACA_EXNMI, paca_struct, exnmi);
#ifdef CONFIG_PPC_PSERIES
OFFSET(PACALPPACAPTR, paca_struct, lppaca_ptr);

5
arch/powerpc/kernel/exceptions-64s.S
View File

@ -1412,13 +1412,9 @@ ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_TYPE_RADIX)
* on user-handler data structures.
*
* KVM: Same as 0x300, DSLB must test for KVM guest.
*
* A dedicated save area EXSLB is used (XXX: but it actually need not be
* these days, we could use EXGEN).
*/
INT_DEFINE_BEGIN(data_access_slb)
IVEC=0x380
IAREA=PACA_EXSLB
IDAR=1
IKVM_SKIP=1
IKVM_REAL=1
@ -1501,7 +1497,6 @@ ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_TYPE_RADIX)
*/
INT_DEFINE_BEGIN(instruction_access_slb)
IVEC=0x480
IAREA=PACA_EXSLB
IISIDE=1
IDAR=1
#ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE