| Message ID | 20170719044946.22030-2-benh@kernel.crashing.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | c433ec0455f921eaf8dd0262a718ce6f8ad62ea2 |
| Headers | show |
Benjamin Herrenschmidt <benh@kernel.crashing.org> a écrit : > By filtering the relevant SRR1 bits in the assembly rather than > in do_page_fault() itself, we avoid a conditional branch (since we > already come from different path for data and instruction faults). > > This will allow more simplifications later > > Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> > --- > arch/powerpc/kernel/head_32.S | 2 +- > arch/powerpc/kernel/head_8xx.S | 4 ++-- > arch/powerpc/mm/fault.c | 14 ++------------ > 3 files changed, 5 insertions(+), 15 deletions(-) > > diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S > index a5301248b098..f11d1cd6e314 100644 > --- a/arch/powerpc/kernel/head_32.S > +++ b/arch/powerpc/kernel/head_32.S > @@ -409,7 +409,7 @@ InstructionAccess: > mr r4,r12 /* SRR0 is fault address */ > bl hash_page > 1: mr r4,r12 > - mr r5,r9 > + andis. r5,r9,0x4820 /* Filter relevant SRR1 bits */ > EXC_XFER_LITE(0x400, handle_page_fault) > > /* External interrupt */ > diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S > index c032fe8c2d26..da3afa2c1658 100644 > --- a/arch/powerpc/kernel/head_8xx.S > +++ b/arch/powerpc/kernel/head_8xx.S > @@ -569,8 +569,8 @@ _ENTRY(DTLBMiss_jmp) > InstructionTLBError: > EXCEPTION_PROLOG > mr r4,r12 > - mr r5,r9 > - andis. r10,r5,0x4000 > + andis. r5,r9,0x4820 /* Filter relevant SRR1 bits */ > + andis. r10,r9,0x4000 > beq+ 1f > tlbie r4 > itlbie: > diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c > index faddc87d0205..f04bc9f6b134 100644 > --- a/arch/powerpc/mm/fault.c > +++ b/arch/powerpc/mm/fault.c > @@ -203,23 +203,13 @@ static int __do_page_fault(struct pt_regs > *regs, unsigned long address, > unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; > int code = SEGV_MAPERR; > int is_write = 0; > - int trap = TRAP(regs); > - int is_exec = trap == 0x400; > + int is_exec = TRAP(regs) == 0x400; Don't we have a tab/space issue here ? > int is_user = user_mode(regs); > int fault; > int rc = 0, store_update_sp = 0; > > #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE)) > - /* > - * Fortunately the bit assignments in SRR1 for an instruction > - * fault and DSISR for a data fault are mostly the same for the > - * bits we are interested in. But there are some bits which > - * indicate errors in DSISR but can validly be set in SRR1. > - */ > - if (is_exec) > - error_code &= 0x48200000; > - else > - is_write = error_code & DSISR_ISSTORE; > + is_write = error_code & DSISR_ISSTORE; > #else > is_write = error_code & ESR_DST; > #endif /* CONFIG_4xx || CONFIG_BOOKE */ > -- > 2.13.3
On Sat, 2017-07-22 at 18:43 +0200, LEROY Christophe wrote: > > > @@ -203,23 +203,13 @@ static int __do_page_fault(struct pt_regs > > *regs, unsigned long address, > > unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; > > int code = SEGV_MAPERR; > > int is_write = 0; > > - int trap = TRAP(regs); > > - int is_exec = trap == 0x400; > > + int is_exec = TRAP(regs) == 0x400; > > Don't we have a tab/space issue here ? There seem to be indeed an extra space before the tab at the beginning of the line, though it looks like it was already there in the orignal code :-) I didn't notice it and thus didn't fix it. If I respin I'll take care of it. > > int is_user = user_mode(regs); > > int fault; > > int rc = 0, store_update_sp = 0; > > > > #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE)) > > - /* > > - * Fortunately the bit assignments in SRR1 for an instruction > > - * fault and DSISR for a data fault are mostly the same for the > > - * bits we are interested in. But there are some bits which > > - * indicate errors in DSISR but can validly be set in SRR1. > > - */ > > - if (is_exec) > > - error_code &= 0x48200000; > > - else > > - is_write = error_code & DSISR_ISSTORE; > > + is_write = error_code & DSISR_ISSTORE; > > #else > > is_write = error_code & ESR_DST; > > #endif /* CONFIG_4xx || CONFIG_BOOKE */ > > -- > > 2.13.3 > >
LEROY Christophe <christophe.leroy@c-s.fr> writes: > Benjamin Herrenschmidt <benh@kernel.crashing.org> a écrit : >> diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c >> index faddc87d0205..f04bc9f6b134 100644 >> --- a/arch/powerpc/mm/fault.c >> +++ b/arch/powerpc/mm/fault.c >> @@ -203,23 +203,13 @@ static int __do_page_fault(struct pt_regs >> *regs, unsigned long address, >> unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; >> int code = SEGV_MAPERR; >> int is_write = 0; >> - int trap = TRAP(regs); >> - int is_exec = trap == 0x400; >> + int is_exec = TRAP(regs) == 0x400; > > Don't we have a tab/space issue here ? We do: Warnings for commit 0f9b89d759ba 'powerpc/mm: Pre-filter SRR1 bits before do_page_fault()' Lines beginning with space in arch/powerpc/mm/fault.c + int is_exec = TRAP(regs) == 0x400; I can fix it up. cheers
diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S index a5301248b098..f11d1cd6e314 100644 --- a/arch/powerpc/kernel/head_32.S +++ b/arch/powerpc/kernel/head_32.S @@ -409,7 +409,7 @@ InstructionAccess: mr r4,r12 /* SRR0 is fault address */ bl hash_page 1: mr r4,r12 - mr r5,r9 + andis. r5,r9,0x4820 /* Filter relevant SRR1 bits */ EXC_XFER_LITE(0x400, handle_page_fault) /* External interrupt */ diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S index c032fe8c2d26..da3afa2c1658 100644 --- a/arch/powerpc/kernel/head_8xx.S +++ b/arch/powerpc/kernel/head_8xx.S @@ -569,8 +569,8 @@ _ENTRY(DTLBMiss_jmp) InstructionTLBError: EXCEPTION_PROLOG mr r4,r12 - mr r5,r9 - andis. r10,r5,0x4000 + andis. r5,r9,0x4820 /* Filter relevant SRR1 bits */ + andis. r10,r9,0x4000 beq+ 1f tlbie r4 itlbie: diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index faddc87d0205..f04bc9f6b134 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -203,23 +203,13 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; int code = SEGV_MAPERR; int is_write = 0; - int trap = TRAP(regs); - int is_exec = trap == 0x400; + int is_exec = TRAP(regs) == 0x400; int is_user = user_mode(regs); int fault; int rc = 0, store_update_sp = 0; #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE)) - /* - * Fortunately the bit assignments in SRR1 for an instruction - * fault and DSISR for a data fault are mostly the same for the - * bits we are interested in. But there are some bits which - * indicate errors in DSISR but can validly be set in SRR1. - */ - if (is_exec) - error_code &= 0x48200000; - else - is_write = error_code & DSISR_ISSTORE; + is_write = error_code & DSISR_ISSTORE; #else is_write = error_code & ESR_DST; #endif /* CONFIG_4xx || CONFIG_BOOKE */
By filtering the relevant SRR1 bits in the assembly rather than in do_page_fault() itself, we avoid a conditional branch (since we already come from different path for data and instruction faults). This will allow more simplifications later Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> --- arch/powerpc/kernel/head_32.S | 2 +- arch/powerpc/kernel/head_8xx.S | 4 ++-- arch/powerpc/mm/fault.c | 14 ++------------ 3 files changed, 5 insertions(+), 15 deletions(-)