[PATCH 02/18] powerpc: remove arguments from fault handler functions
Christophe Leroy
christophe.leroy at csgroup.eu
Fri Nov 6 18:59:26 AEDT 2020
Le 05/11/2020 à 15:34, Nicholas Piggin a écrit :
> Make mm fault handlers all just take the pt_regs * argument and load
> DAR/DSISR from that. Make those that return a value return long.
>
> This is done to make the function signatures match other handlers, which
> will help with a future patch to add wrappers. Explicit arguments could
> be added for performance but that would require more wrapper macro
> variants.
>
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> ---
> arch/powerpc/include/asm/asm-prototypes.h | 4 ++--
> arch/powerpc/include/asm/bug.h | 4 ++--
> arch/powerpc/kernel/exceptions-64e.S | 2 --
> arch/powerpc/kernel/exceptions-64s.S | 14 ++------------
> arch/powerpc/kernel/head_40x.S | 10 +++++-----
> arch/powerpc/kernel/head_8xx.S | 6 +++---
> arch/powerpc/kernel/head_book3s_32.S | 6 ++----
> arch/powerpc/kernel/head_booke.h | 4 +---
> arch/powerpc/mm/book3s64/hash_utils.c | 8 +++++---
> arch/powerpc/mm/book3s64/slb.c | 11 +++++++----
> arch/powerpc/mm/fault.c | 16 +++++++++-------
> 11 files changed, 38 insertions(+), 47 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/asm-prototypes.h b/arch/powerpc/include/asm/asm-prototypes.h
> index d0b832cbbec8..22c9d08fa3a4 100644
> --- a/arch/powerpc/include/asm/asm-prototypes.h
> +++ b/arch/powerpc/include/asm/asm-prototypes.h
> @@ -82,8 +82,8 @@ void kernel_bad_stack(struct pt_regs *regs);
> void system_reset_exception(struct pt_regs *regs);
> void machine_check_exception(struct pt_regs *regs);
> void emulation_assist_interrupt(struct pt_regs *regs);
> -long do_slb_fault(struct pt_regs *regs, unsigned long ea);
> -void do_bad_slb_fault(struct pt_regs *regs, unsigned long ea, long err);
> +long do_slb_fault(struct pt_regs *regs);
> +void do_bad_slb_fault(struct pt_regs *regs);
>
> /* signals, syscalls and interrupts */
> long sys_swapcontext(struct ucontext __user *old_ctx,
> diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h
> index d714d83bbc7c..2fa0cf6c6011 100644
> --- a/arch/powerpc/include/asm/bug.h
> +++ b/arch/powerpc/include/asm/bug.h
> @@ -111,8 +111,8 @@
> #ifndef __ASSEMBLY__
>
> struct pt_regs;
> -extern int do_page_fault(struct pt_regs *, unsigned long, unsigned long);
> -extern int hash__do_page_fault(struct pt_regs *, unsigned long, unsigned long);
> +extern long do_page_fault(struct pt_regs *);
> +extern long hash__do_page_fault(struct pt_regs *);
extern is pointless
> extern void bad_page_fault(struct pt_regs *, unsigned long, int);
> extern void _exception(int, struct pt_regs *, int, unsigned long);
> extern void _exception_pkey(struct pt_regs *, unsigned long, int);
> diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
> index f579ce46eef2..25fa7d5a643c 100644
> --- a/arch/powerpc/kernel/exceptions-64e.S
> +++ b/arch/powerpc/kernel/exceptions-64e.S
> @@ -1011,8 +1011,6 @@ storage_fault_common:
> std r14,_DAR(r1)
> std r15,_DSISR(r1)
> addi r3,r1,STACK_FRAME_OVERHEAD
> - mr r4,r14
> - mr r5,r15
> ld r14,PACA_EXGEN+EX_R14(r13)
> ld r15,PACA_EXGEN+EX_R15(r13)
> bl do_page_fault
> diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
> index f830b893fe03..1f34cfd1887c 100644
> --- a/arch/powerpc/kernel/exceptions-64s.S
> +++ b/arch/powerpc/kernel/exceptions-64s.S
> @@ -1437,8 +1437,6 @@ EXC_VIRT_BEGIN(data_access, 0x4300, 0x80)
> EXC_VIRT_END(data_access, 0x4300, 0x80)
> EXC_COMMON_BEGIN(data_access_common)
> GEN_COMMON data_access
> - ld r4,_DAR(r1)
> - ld r5,_DSISR(r1)
> addi r3,r1,STACK_FRAME_OVERHEAD
> BEGIN_MMU_FTR_SECTION
> bl do_hash_fault
> @@ -1491,10 +1489,9 @@ EXC_VIRT_BEGIN(data_access_slb, 0x4380, 0x80)
> EXC_VIRT_END(data_access_slb, 0x4380, 0x80)
> EXC_COMMON_BEGIN(data_access_slb_common)
> GEN_COMMON data_access_slb
> - ld r4,_DAR(r1)
> - addi r3,r1,STACK_FRAME_OVERHEAD
> BEGIN_MMU_FTR_SECTION
> /* HPT case, do SLB fault */
> + addi r3,r1,STACK_FRAME_OVERHEAD
> bl do_slb_fault
> cmpdi r3,0
> bne- 1f
> @@ -1506,8 +1503,6 @@ MMU_FTR_SECTION_ELSE
> ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_TYPE_RADIX)
> std r3,RESULT(r1)
> RECONCILE_IRQ_STATE(r10, r11)
> - ld r4,_DAR(r1)
> - ld r5,RESULT(r1)
> addi r3,r1,STACK_FRAME_OVERHEAD
> bl do_bad_slb_fault
> b interrupt_return
> @@ -1542,8 +1537,6 @@ EXC_VIRT_BEGIN(instruction_access, 0x4400, 0x80)
> EXC_VIRT_END(instruction_access, 0x4400, 0x80)
> EXC_COMMON_BEGIN(instruction_access_common)
> GEN_COMMON instruction_access
> - ld r4,_DAR(r1)
> - ld r5,_DSISR(r1)
> addi r3,r1,STACK_FRAME_OVERHEAD
> BEGIN_MMU_FTR_SECTION
> bl do_hash_fault
> @@ -1587,10 +1580,9 @@ EXC_VIRT_BEGIN(instruction_access_slb, 0x4480, 0x80)
> EXC_VIRT_END(instruction_access_slb, 0x4480, 0x80)
> EXC_COMMON_BEGIN(instruction_access_slb_common)
> GEN_COMMON instruction_access_slb
> - ld r4,_DAR(r1)
> - addi r3,r1,STACK_FRAME_OVERHEAD
> BEGIN_MMU_FTR_SECTION
> /* HPT case, do SLB fault */
> + addi r3,r1,STACK_FRAME_OVERHEAD
> bl do_slb_fault
> cmpdi r3,0
> bne- 1f
> @@ -1602,8 +1594,6 @@ MMU_FTR_SECTION_ELSE
> ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_TYPE_RADIX)
> std r3,RESULT(r1)
> RECONCILE_IRQ_STATE(r10, r11)
> - ld r4,_DAR(r1)
> - ld r5,RESULT(r1)
> addi r3,r1,STACK_FRAME_OVERHEAD
> bl do_bad_slb_fault
> b interrupt_return
> diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
> index 44c9018aed1b..ea31f75e9692 100644
> --- a/arch/powerpc/kernel/head_40x.S
> +++ b/arch/powerpc/kernel/head_40x.S
> @@ -179,9 +179,9 @@ _ENTRY(saved_ksp_limit)
> */
> START_EXCEPTION(0x0300, DataStorage)
> EXCEPTION_PROLOG
> - mfspr r5, SPRN_ESR /* Grab the ESR, save it, pass arg3 */
> + mfspr r5, SPRN_ESR /* Grab the ESR, save it */
> stw r5, _ESR(r11)
> - mfspr r4, SPRN_DEAR /* Grab the DEAR, save it, pass arg2 */
> + mfspr r4, SPRN_DEAR /* Grab the DEAR, save it */
> stw r4, _DEAR(r11)
> EXC_XFER_LITE(0x300, handle_page_fault)
>
> @@ -191,9 +191,9 @@ _ENTRY(saved_ksp_limit)
> */
> START_EXCEPTION(0x0400, InstructionAccess)
> EXCEPTION_PROLOG
> - mr r4,r12 /* Pass SRR0 as arg2 */
> - stw r4, _DEAR(r11)
> - li r5,0 /* Pass zero as arg3 */
> + li r5,0
> + stw r5, _ESR(r11) /* Zero ESR */
> + stw r12, _DEAR(r11) /* SRR0 as DEAR */
I think we should avoid this, see below
> EXC_XFER_LITE(0x400, handle_page_fault)
>
> /* 0x0500 - External Interrupt Exception */
> diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
> index 9f359d3fba74..0cd95b633e2b 100644
> --- a/arch/powerpc/kernel/head_8xx.S
> +++ b/arch/powerpc/kernel/head_8xx.S
> @@ -356,14 +356,14 @@ DataStoreTLBMiss:
> . = 0x1300
> InstructionTLBError:
> EXCEPTION_PROLOG
> - mr r4,r12
> andis. r5,r9,DSISR_SRR1_MATCH_32S at h /* Filter relevant SRR1 bits */
Could avoid this, see below
> andis. r10,r9,SRR1_ISI_NOPT at h
> beq+ .Litlbie
> - tlbie r4
> + tlbie r12
> /* 0x400 is InstructionAccess exception, needed by bad_page_fault() */
> .Litlbie:
> - stw r4, _DAR(r11)
> + stw r12, _DAR(r11)
> + stw r5, _DSISR(r11)
And this
> EXC_XFER_LITE(0x400, handle_page_fault)
>
> /* This is the data TLB error on the MPC8xx. This could be due to
> diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S
> index 5eb9eedac920..81c69769cec6 100644
> --- a/arch/powerpc/kernel/head_book3s_32.S
> +++ b/arch/powerpc/kernel/head_book3s_32.S
> @@ -369,9 +369,9 @@ BEGIN_MMU_FTR_SECTION
> bl hash_page
> END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
> #endif /* CONFIG_VMAP_STACK */
> -1: mr r4,r12
> andis. r5,r9,DSISR_SRR1_MATCH_32S at h /* Filter relevant SRR1 bits */
> - stw r4, _DAR(r11)
> + stw r5, _DSISR(r11)
> + stw r12, _DAR(r11)
And this including the andis.
> EXC_XFER_LITE(0x400, handle_page_fault)
>
> /* External interrupt */
> @@ -698,8 +698,6 @@ handle_page_fault_tramp_1:
> #ifdef CONFIG_VMAP_STACK
> EXCEPTION_PROLOG_2 handle_dar_dsisr=1
> #endif
> - lwz r4, _DAR(r11)
> - lwz r5, _DSISR(r11)
> /* fall through */
> handle_page_fault_tramp_2:
> EXC_XFER_LITE(0x300, handle_page_fault)
> diff --git a/arch/powerpc/kernel/head_booke.h b/arch/powerpc/kernel/head_booke.h
> index 71c359d438b5..1da0c1d1b0a1 100644
> --- a/arch/powerpc/kernel/head_booke.h
> +++ b/arch/powerpc/kernel/head_booke.h
> @@ -477,9 +477,7 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
> NORMAL_EXCEPTION_PROLOG(INST_STORAGE); \
> mfspr r5,SPRN_ESR; /* Grab the ESR and save it */ \
> stw r5,_ESR(r11); \
> - mr r4,r12; /* Pass SRR0 as arg2 */ \
> - stw r4, _DEAR(r11); \
> - li r5,0; /* Pass zero as arg3 */ \
> + stw r12, _DEAR(r11); /* Pass SRR0 as arg2 */ \
And this
> EXC_XFER_LITE(0x0400, handle_page_fault)
>
> #define ALIGNMENT_EXCEPTION \
> diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c
> index bfa1b1966218..0f0bd4af4b2d 100644
> --- a/arch/powerpc/mm/book3s64/hash_utils.c
> +++ b/arch/powerpc/mm/book3s64/hash_utils.c
> @@ -1510,13 +1510,15 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap,
> }
> EXPORT_SYMBOL_GPL(hash_page);
>
> -int do_hash_fault(struct pt_regs *regs, unsigned long ea, unsigned long dsisr)
> +long do_hash_fault(struct pt_regs *regs)
> {
> + unsigned long ea = regs->dar;
> + unsigned long dsisr = regs->dsisr;
> unsigned long access = _PAGE_PRESENT | _PAGE_READ;
> unsigned long flags = 0;
> struct mm_struct *mm;
> unsigned int region_id;
> - int err;
> + long err;
>
> if (unlikely(dsisr & (DSISR_BAD_FAULT_64S | DSISR_DABRMATCH | DSISR_KEYFAULT)))
> goto _do_page_fault;
> @@ -1580,7 +1582,7 @@ int do_hash_fault(struct pt_regs *regs, unsigned long ea, unsigned long dsisr)
>
> } else if (err) {
> _do_page_fault:
> - err = hash__do_page_fault(regs, ea, dsisr);
> + err = hash__do_page_fault(regs);
> }
>
> return err;
> diff --git a/arch/powerpc/mm/book3s64/slb.c b/arch/powerpc/mm/book3s64/slb.c
> index c30fcbfa0e32..cc34d50874c1 100644
> --- a/arch/powerpc/mm/book3s64/slb.c
> +++ b/arch/powerpc/mm/book3s64/slb.c
> @@ -837,8 +837,9 @@ static long slb_allocate_user(struct mm_struct *mm, unsigned long ea)
> return slb_insert_entry(ea, context, flags, ssize, false);
> }
>
> -long do_slb_fault(struct pt_regs *regs, unsigned long ea)
> +long do_slb_fault(struct pt_regs *regs)
> {
> + unsigned long ea = regs->dar;
> unsigned long id = get_region_id(ea);
>
> /* IRQs are not reconciled here, so can't check irqs_disabled */
> @@ -889,13 +890,15 @@ long do_slb_fault(struct pt_regs *regs, unsigned long ea)
> }
> }
>
> -void do_bad_slb_fault(struct pt_regs *regs, unsigned long ea, long err)
> +void do_bad_slb_fault(struct pt_regs *regs)
> {
> + int err = regs->result;
> +
> if (err == -EFAULT) {
> if (user_mode(regs))
> - _exception(SIGSEGV, regs, SEGV_BNDERR, ea);
> + _exception(SIGSEGV, regs, SEGV_BNDERR, regs->dar);
> else
> - bad_page_fault(regs, ea, SIGSEGV);
> + bad_page_fault(regs, regs->dar, SIGSEGV);
> } else if (err == -EINVAL) {
> unrecoverable_exception(regs);
> } else {
> diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
> index e65a49f246ef..390a296b16a3 100644
> --- a/arch/powerpc/mm/fault.c
> +++ b/arch/powerpc/mm/fault.c
> @@ -549,11 +549,12 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
> }
> NOKPROBE_SYMBOL(__do_page_fault);
>
> -int do_page_fault(struct pt_regs *regs, unsigned long address,
> - unsigned long error_code)
> +long do_page_fault(struct pt_regs *regs)
> {
> enum ctx_state prev_state = exception_enter();
> - int err;
> + unsigned long address = regs->dar;
> + unsigned long error_code = regs->dsisr;
> + long err;
By doing something more or less like this (need to be tuned for bookE as well):
+ int is_exec = TRAP(regs) == 0x400;
+ unsigned long address = is_exec ? regs->ssr0 : regs->dar;
+ unsigned long error_code = is_exec ? (regs->ssr1 & DSISR_SRR1_MATCH_32S) : regs->dsisr;
>
> err = __do_page_fault(regs, address, error_code);
>
> @@ -580,11 +581,12 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
> NOKPROBE_SYMBOL(do_page_fault);
>
> #ifdef CONFIG_PPC_BOOK3S_64
> -/* Same as do_page_fault but interrupt entry has already run in do_hash_fault */
> -int hash__do_page_fault(struct pt_regs *regs, unsigned long address,
> - unsigned long error_code)
> +/* Same as do_page_fault but no interrupt entry */
> +long hash__do_page_fault(struct pt_regs *regs)
> {
> - int err;
> + unsigned long address = regs->dar;
> + unsigned long error_code = regs->dsisr;
> + long err;
>
> err = __do_page_fault(regs, address, error_code);
> if (unlikely(err)) {
>
There is probably also something we can simplify around get_and_save_dar_dsisr_on_stack() macro in
head_32.h, no need to reload DAR, at least for 8xx. Maybe as a followup patch later.
Christophe
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