Le 26/09/2022 à 05:40, Nicholas Piggin a écrit : > Using a 32-bit constant for this marker allows it to be loaded with > two ALU instructions, like 32-bit. This avoids a TOC entry and a > TOC load that depends on the r2 value that has just been loaded from > the PACA. > > This changes the value for 32-bit as well, so both have the same > value in the low 4 bytes and 64-bit has 0xffffffff in the top bytes.
The above is wrong now, isn't it ? > > Signed-off-by: Nicholas Piggin <npig...@gmail.com> > --- > arch/powerpc/include/asm/ptrace.h | 4 ++-- > arch/powerpc/kernel/entry_32.S | 6 +++--- > arch/powerpc/kernel/exceptions-64e.S | 8 +------- > arch/powerpc/kernel/exceptions-64s.S | 2 +- > arch/powerpc/kernel/head_64.S | 7 ------- > arch/powerpc/kernel/interrupt_64.S | 6 +++--- > 6 files changed, 10 insertions(+), 23 deletions(-) > > diff --git a/arch/powerpc/include/asm/ptrace.h > b/arch/powerpc/include/asm/ptrace.h > index a03403695cd4..5b496e589d54 100644 > --- a/arch/powerpc/include/asm/ptrace.h > +++ b/arch/powerpc/include/asm/ptrace.h > @@ -99,6 +99,8 @@ struct pt_regs > > #define STACK_FRAME_WITH_PT_REGS (STACK_FRAME_OVERHEAD + sizeof(struct > pt_regs)) > > +#define STACK_FRAME_REGS_MARKER ASM_CONST(0x72656773) > + > #ifdef __powerpc64__ > > /* > @@ -115,7 +117,6 @@ struct pt_regs > > #define STACK_FRAME_OVERHEAD 112 /* size of minimum stack frame > */ > #define STACK_FRAME_LR_SAVE 2 /* Location of LR in stack frame */ > -#define STACK_FRAME_REGS_MARKER ASM_CONST(0x7265677368657265) > #define STACK_INT_FRAME_SIZE (sizeof(struct pt_regs) + \ > STACK_FRAME_OVERHEAD + KERNEL_REDZONE_SIZE) > #define STACK_FRAME_MARKER 12 > @@ -136,7 +137,6 @@ struct pt_regs > #define KERNEL_REDZONE_SIZE 0 > #define STACK_FRAME_OVERHEAD 16 /* size of minimum stack frame > */ > #define STACK_FRAME_LR_SAVE 1 /* Location of LR in stack frame */ > -#define STACK_FRAME_REGS_MARKER ASM_CONST(0x72656773) > #define STACK_INT_FRAME_SIZE (sizeof(struct pt_regs) + > STACK_FRAME_OVERHEAD) > #define STACK_FRAME_MARKER 2 > #define STACK_FRAME_MIN_SIZE STACK_FRAME_OVERHEAD > diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S > index 1d599df6f169..c2516f982cfa 100644 > --- a/arch/powerpc/kernel/entry_32.S > +++ b/arch/powerpc/kernel/entry_32.S > @@ -265,7 +265,7 @@ fast_exception_return: > mtcr r10 > lwz r10,_LINK(r11) > mtlr r10 > - /* Clear the exception_marker on the stack to avoid confusing > stacktrace */ > + /* Clear the exception marker on the stack to avoid confusing > stacktrace */ > li r10, 0 > stw r10, 8(r11) > REST_GPR(10, r11) > @@ -322,7 +322,7 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS) > li r0,0 > > /* > - * Leaving a stale exception_marker on the stack can confuse > + * Leaving a stale exception marker on the stack can confuse > * the reliable stack unwinder later on. Clear it. > */ > stw r0,8(r1) > @@ -374,7 +374,7 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS) > mtspr SPRN_XER,r5 > > /* > - * Leaving a stale exception_marker on the stack can confuse > + * Leaving a stale exception marker on the stack can confuse > * the reliable stack unwinder later on. Clear it. > */ > stw r0,8(r1) > diff --git a/arch/powerpc/kernel/exceptions-64e.S > b/arch/powerpc/kernel/exceptions-64e.S > index 67dc4e3179a0..08a3139079b7 100644 > --- a/arch/powerpc/kernel/exceptions-64e.S > +++ b/arch/powerpc/kernel/exceptions-64e.S > @@ -389,7 +389,7 @@ exc_##n##_common: > \ > ld r9,excf+EX_R1(r13); /* load orig r1 back from PACA */ \ > lwz r10,excf+EX_CR(r13); /* load orig CR back from PACA */ \ > lbz r11,PACAIRQSOFTMASK(r13); /* get current IRQ softe */ \ > - ld r12,exception_marker@toc(r2); \ > + LOAD_REG_IMMEDIATE(r12, STACK_FRAME_REGS_MARKER); \ > li r0,0; \ > std r3,GPR10(r1); /* save r10 to stackframe */ \ > std r4,GPR11(r1); /* save r11 to stackframe */ \ > @@ -470,12 +470,6 @@ exc_##n##_bad_stack: > \ > bl hdlr; \ > b interrupt_return > > -/* This value is used to mark exception frames on the stack. */ > - .section ".toc","aw" > -exception_marker: > - .tc ID_EXC_MARKER[TC],STACK_FRAME_REGS_MARKER > - > - > /* > * And here we have the exception vectors ! > */ > diff --git a/arch/powerpc/kernel/exceptions-64s.S > b/arch/powerpc/kernel/exceptions-64s.S > index 3d0dc133a9ae..9d375ea58add 100644 > --- a/arch/powerpc/kernel/exceptions-64s.S > +++ b/arch/powerpc/kernel/exceptions-64s.S > @@ -589,7 +589,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_CFAR) > li r9,IVEC > std r9,_TRAP(r1) /* set trap number */ > li r10,0 > - ld r11,exception_marker@toc(r2) > + LOAD_REG_IMMEDIATE(r11, STACK_FRAME_REGS_MARKER) > std r10,RESULT(r1) /* clear regs->result */ > std r11,STACK_FRAME_OVERHEAD-16(r1) /* mark the frame */ > .endm > diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S > index cf2c08902c05..cac3e1b58360 100644 > --- a/arch/powerpc/kernel/head_64.S > +++ b/arch/powerpc/kernel/head_64.S > @@ -192,13 +192,6 @@ __secondary_hold: > #endif > CLOSE_FIXED_SECTION(first_256B) > > -/* This value is used to mark exception frames on the stack. */ > - .section ".toc","aw" > -/* This value is used to mark exception frames on the stack. */ > -exception_marker: > - .tc ID_EXC_MARKER[TC],STACK_FRAME_REGS_MARKER > - .previous > - > /* > * On server, we include the exception vectors code here as it > * relies on absolute addressing which is only possible within > diff --git a/arch/powerpc/kernel/interrupt_64.S > b/arch/powerpc/kernel/interrupt_64.S > index ce25b28cf418..ee2d2d410c5a 100644 > --- a/arch/powerpc/kernel/interrupt_64.S > +++ b/arch/powerpc/kernel/interrupt_64.S > @@ -92,7 +92,7 @@ _ASM_NOKPROBE_SYMBOL(system_call_vectored_\name) > std r11,_TRAP(r1) > std r12,_CCR(r1) > addi r10,r1,STACK_FRAME_OVERHEAD > - ld r11,exception_marker@toc(r2) > + LOAD_REG_IMMEDIATE(r11, STACK_FRAME_REGS_MARKER) > std r11,-16(r10) /* "regshere" marker */ > > BEGIN_FTR_SECTION > @@ -276,7 +276,7 @@ END_BTB_FLUSH_SECTION > std r11,_TRAP(r1) > std r12,_CCR(r1) > addi r10,r1,STACK_FRAME_OVERHEAD > - ld r11,exception_marker@toc(r2) > + LOAD_REG_IMMEDIATE(r11, STACK_FRAME_REGS_MARKER) > std r11,-16(r10) /* "regshere" marker */ > > #ifdef CONFIG_PPC_BOOK3S > @@ -619,7 +619,7 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS) > mtspr SPRN_XER,r5 > > /* > - * Leaving a stale exception_marker on the stack can confuse > + * Leaving a stale STACK_FRAME_REGS_MARKER on the stack can confuse > * the reliable stack unwinder later on. Clear it. > */ > std r0,STACK_FRAME_OVERHEAD-16(r1)
