From 9d378dfac885f72b8b369d08fc61bef36e2f2dd1 Mon Sep 17 00:00:00 2001 From: Scott Wood Date: Mon, 10 Mar 2014 17:29:38 -0500 Subject: powerpc/booke64: Use SPRG7 for VDSO Previously SPRG3 was marked for use by both VDSO and critical interrupts (though critical interrupts were not fully implemented). In commit 8b64a9dfb091f1eca8b7e58da82f1e7d1d5fe0ad ("powerpc/booke64: Use SPRG0/3 scratch for bolted TLB miss & crit int"), Mihai Caraman made an attempt to resolve this conflict by restoring the VDSO value early in the critical interrupt, but this has some issues: - It's incompatible with EXCEPTION_COMMON which restores r13 from the by-then-overwritten scratch (this cost me some debugging time). - It forces critical exceptions to be a special case handled differently from even machine check and debug level exceptions. - It didn't occur to me that it was possible to make this work at all (by doing a final "ld r13, PACA_EXCRIT+EX_R13(r13)") until after I made (most of) this patch. :-) It might be worth investigating using a load rather than SPRG on return from all exceptions (except TLB misses where the scratch never leaves the SPRG) -- it could save a few cycles. Until then, let's stick with SPRG for all exceptions. Since we cannot use SPRG4-7 for scratch without corrupting the state of a KVM guest, move VDSO to SPRG7 on book3e. Since neither SPRG4-7 nor critical interrupts exist on book3s, SPRG3 is still used for VDSO there. Signed-off-by: Scott Wood Cc: Mihai Caraman Cc: Anton Blanchard Cc: Paul Mackerras Cc: kvm-ppc@vger.kernel.org --- arch/powerpc/kernel/asm-offsets.c | 2 +- arch/powerpc/kernel/exceptions-64e.S | 19 ++----------------- arch/powerpc/kernel/vdso.c | 8 ++++---- arch/powerpc/kernel/vdso32/getcpu.S | 2 +- arch/powerpc/kernel/vdso64/getcpu.S | 2 +- 5 files changed, 9 insertions(+), 24 deletions(-) (limited to 'arch/powerpc/kernel') diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index b5aacf72ae6..dba8140ebc2 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -253,7 +253,7 @@ int main(void) DEFINE(PACA_SYSTEM_TIME, offsetof(struct paca_struct, system_time)); DEFINE(PACA_TRAP_SAVE, offsetof(struct paca_struct, trap_save)); DEFINE(PACA_NAPSTATELOST, offsetof(struct paca_struct, nap_state_lost)); - DEFINE(PACA_SPRG3, offsetof(struct paca_struct, sprg3)); + DEFINE(PACA_SPRG_VDSO, offsetof(struct paca_struct, sprg_vdso)); #endif /* CONFIG_PPC64 */ /* RTAS */ diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S index 41380a42410..89e1133b018 100644 --- a/arch/powerpc/kernel/exceptions-64e.S +++ b/arch/powerpc/kernel/exceptions-64e.S @@ -55,7 +55,6 @@ mfspr r13,SPRN_SPRG_PACA; /* get PACA */ \ std r10,PACA_EX##type+EX_R10(r13); \ std r11,PACA_EX##type+EX_R11(r13); \ - PROLOG_STORE_RESTORE_SCRATCH_##type; \ mfcr r10; /* save CR */ \ mfspr r11,SPRN_##type##_SRR1;/* what are we coming from */ \ DO_KVM intnum,SPRN_##type##_SRR1; /* KVM hook */ \ @@ -116,20 +115,6 @@ #define GDBELL_EXCEPTION_PROLOG(n, intnum, addition) \ EXCEPTION_PROLOG(n, intnum, GDBELL, addition##_GDBELL(n)) -/* - * Store user-visible scratch in PACA exception slots and restore proper value - */ -#define PROLOG_STORE_RESTORE_SCRATCH_GEN -#define PROLOG_STORE_RESTORE_SCRATCH_GDBELL -#define PROLOG_STORE_RESTORE_SCRATCH_DBG -#define PROLOG_STORE_RESTORE_SCRATCH_MC - -#define PROLOG_STORE_RESTORE_SCRATCH_CRIT \ - mfspr r10,SPRN_SPRG_CRIT_SCRATCH; /* get r13 */ \ - std r10,PACA_EXCRIT+EX_R13(r13); \ - ld r11,PACA_SPRG3(r13); \ - mtspr SPRN_SPRG_CRIT_SCRATCH,r11; - /* Variants of the "addition" argument for the prolog */ #define PROLOG_ADDITION_NONE_GEN(n) @@ -529,7 +514,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC) mtcr r10 ld r10,PACA_EXCRIT+EX_R10(r13) /* restore registers */ ld r11,PACA_EXCRIT+EX_R11(r13) - ld r13,PACA_EXCRIT+EX_R13(r13) + mfspr r13,SPRN_SPRG_CRIT_SCRATCH rfci /* Normal debug exception */ @@ -542,7 +527,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC) /* Now we mash up things to make it look like we are coming on a * normal exception */ - ld r15,PACA_EXCRIT+EX_R13(r13) + mfspr r15,SPRN_SPRG_CRIT_SCRATCH mtspr SPRN_SPRG_GEN_SCRATCH,r15 mfspr r14,SPRN_DBSR EXCEPTION_COMMON(0xd00, PACA_EXCRIT, INTS_DISABLE) diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c index 094e45c16a1..ce74c335a6a 100644 --- a/arch/powerpc/kernel/vdso.c +++ b/arch/powerpc/kernel/vdso.c @@ -715,8 +715,8 @@ int vdso_getcpu_init(void) unsigned long cpu, node, val; /* - * SPRG3 contains the CPU in the bottom 16 bits and the NUMA node in - * the next 16 bits. The VDSO uses this to implement getcpu(). + * SPRG_VDSO contains the CPU in the bottom 16 bits and the NUMA node + * in the next 16 bits. The VDSO uses this to implement getcpu(). */ cpu = get_cpu(); WARN_ON_ONCE(cpu > 0xffff); @@ -725,8 +725,8 @@ int vdso_getcpu_init(void) WARN_ON_ONCE(node > 0xffff); val = (cpu & 0xfff) | ((node & 0xffff) << 16); - mtspr(SPRN_SPRG3, val); - get_paca()->sprg3 = val; + mtspr(SPRN_SPRG_VDSO_WRITE, val); + get_paca()->sprg_vdso = val; put_cpu(); diff --git a/arch/powerpc/kernel/vdso32/getcpu.S b/arch/powerpc/kernel/vdso32/getcpu.S index 47afd08c90f..23eb9a9441b 100644 --- a/arch/powerpc/kernel/vdso32/getcpu.S +++ b/arch/powerpc/kernel/vdso32/getcpu.S @@ -29,7 +29,7 @@ */ V_FUNCTION_BEGIN(__kernel_getcpu) .cfi_startproc - mfspr r5,SPRN_USPRG3 + mfspr r5,SPRN_SPRG_VDSO_READ cmpdi cr0,r3,0 cmpdi cr1,r4,0 clrlwi r6,r5,16 diff --git a/arch/powerpc/kernel/vdso64/getcpu.S b/arch/powerpc/kernel/vdso64/getcpu.S index 47afd08c90f..23eb9a9441b 100644 --- a/arch/powerpc/kernel/vdso64/getcpu.S +++ b/arch/powerpc/kernel/vdso64/getcpu.S @@ -29,7 +29,7 @@ */ V_FUNCTION_BEGIN(__kernel_getcpu) .cfi_startproc - mfspr r5,SPRN_USPRG3 + mfspr r5,SPRN_SPRG_VDSO_READ cmpdi cr0,r3,0 cmpdi cr1,r4,0 clrlwi r6,r5,16 -- cgit v1.2.3-70-g09d2