Re: [PATCH 02/24] powerpc/mm: Pre-filter SRR1 bits before do_page_fault()
From: LEROY Christophe <hidden>
Date: 2017-07-22 16:43:22
Benjamin Herrenschmidt [off-list ref] a =C3=A9crit=C2=A0:
quoted hunk ↗ jump to hunk
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
quoted hunk ↗ jump to hunk
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_8x=
x.S
quoted hunk ↗ jump to hunk
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=20=20=20*regs, unsigned long address, unsigned int flags =3D FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; int code =3D SEGV_MAPERR; int is_write =3D 0; - int trap =3D TRAP(regs); - int is_exec =3D trap =3D=3D 0x400; + int is_exec =3D TRAP(regs) =3D=3D 0x400;
Don't we have a tab/space issue here ?
int is_user =3D user_mode(regs); int fault; int rc =3D 0, store_update_sp =3D 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 &=3D 0x48200000; - else - is_write =3D error_code & DSISR_ISSTORE; + is_write =3D error_code & DSISR_ISSTORE; #else is_write =3D error_code & ESR_DST; #endif /* CONFIG_4xx || CONFIG_BOOKE */ -- 2.13.3