| Message ID | 20151125172902.82C6C69260@newverein.lst.de (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On 11/25/15, Torsten Duwe <duwe@lst.de> wrote: > Implement FTRACE_WITH_REGS for powerpc64, on ELF ABI v2. > Initial work started by Vojtech Pavlik, used with permission. > > * arch/powerpc/kernel/entry_64.S: > - Implement an effective ftrace_caller that works from > within the kernel binary as well as from modules. > * arch/powerpc/kernel/ftrace.c: > - be prepared to deal with ppc64 ELF ABI v2, especially > calls to _mcount that result from gcc -mprofile-kernel > - a little more error verbosity > * arch/powerpc/kernel/module_64.c: > - do not save the TOC pointer on the trampoline when the > destination is ftrace_caller. This trampoline jump happens from > a function prologue before a new stack frame is set up, so bad > things may happen otherwise... > - relax is_module_trampoline() to recognise the modified > trampoline. > > Signed-off-by: Torsten Duwe <duwe@suse.de> > --- > arch/powerpc/include/asm/ftrace.h | 5 +++ > arch/powerpc/kernel/entry_64.S | 77 > +++++++++++++++++++++++++++++++++++++++ > arch/powerpc/kernel/ftrace.c | 60 +++++++++++++++++++++++++++--- > arch/powerpc/kernel/module_64.c | 25 ++++++++++++- > 4 files changed, 160 insertions(+), 7 deletions(-) > > diff --git a/arch/powerpc/include/asm/ftrace.h > b/arch/powerpc/include/asm/ftrace.h > index ef89b14..50ca758 100644 > --- a/arch/powerpc/include/asm/ftrace.h > +++ b/arch/powerpc/include/asm/ftrace.h > @@ -46,6 +46,8 @@ > extern void _mcount(void); > > #ifdef CONFIG_DYNAMIC_FTRACE > +# define FTRACE_ADDR ((unsigned long)ftrace_caller) > +# define FTRACE_REGS_ADDR FTRACE_ADDR > static inline unsigned long ftrace_call_adjust(unsigned long addr) > { > /* reloction of mcount call site is the same as the address */ > @@ -58,6 +60,9 @@ struct dyn_arch_ftrace { > #endif /* CONFIG_DYNAMIC_FTRACE */ > #endif /* __ASSEMBLY__ */ > > +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > +#define ARCH_SUPPORTS_FTRACE_OPS 1 > +#endif > #endif > > #if defined(CONFIG_FTRACE_SYSCALLS) && defined(CONFIG_PPC64) && > !defined(__ASSEMBLY__) > diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S > index 8d56b16..3309dd8 100644 > --- a/arch/powerpc/kernel/entry_64.S > +++ b/arch/powerpc/kernel/entry_64.S Linux style for comments is the C89. Please update entry_64.S > @@ -1212,6 +1212,7 @@ _GLOBAL(_mcount) > mtlr r0 > bctr > > +#ifndef CC_USING_MPROFILE_KERNEL > _GLOBAL_TOC(ftrace_caller) > /* Taken from output of objdump from lib64/glibc */ > mflr r3 > @@ -1233,6 +1234,82 @@ _GLOBAL(ftrace_graph_stub) > ld r0, 128(r1) > mtlr r0 > addi r1, r1, 112 > +#else > +_GLOBAL(ftrace_caller) > +#if defined(_CALL_ELF) && _CALL_ELF == 2 > + mflr r0 > + bl 2f > +2: mflr r12 > + mtlr r0 > + mr r0,r2 // save callee's TOC > + addis r2,r12,(.TOC.-ftrace_caller-8)@ha > + addi r2,r2,(.TOC.-ftrace_caller-8)@l > +#else > + mr r0,r2 > +#endif > + ld r12,LRSAVE(r1) // get caller's address > + > + stdu r1,-SWITCH_FRAME_SIZE(r1) > + > + std r12, _LINK(r1) > + SAVE_8GPRS(0,r1) > + std r0, 24(r1) // save TOC > + SAVE_8GPRS(8,r1) > + SAVE_8GPRS(16,r1) > + SAVE_8GPRS(24,r1) > + > + addis r3,r2,function_trace_op@toc@ha > + addi r3,r3,function_trace_op@toc@l > + ld r5,0(r3) > + > + mflr r3 > + std r3, _NIP(r1) > + std r3, 16(r1) > + subi r3, r3, MCOUNT_INSN_SIZE > + mfmsr r4 > + std r4, _MSR(r1) > + mfctr r4 > + std r4, _CTR(r1) > + mfxer r4 > + std r4, _XER(r1) > + mr r4, r12 > + addi r6, r1 ,STACK_FRAME_OVERHEAD > + > +.globl ftrace_call > +ftrace_call: > + bl ftrace_stub > + nop > + > + ld r3, _NIP(r1) > + mtlr r3 > + > + REST_8GPRS(0,r1) > + REST_8GPRS(8,r1) > + REST_8GPRS(16,r1) > + REST_8GPRS(24,r1) > + > + addi r1, r1, SWITCH_FRAME_SIZE > + > + ld r12, LRSAVE(r1) // get caller's address > + mtlr r12 > + mr r2,r0 // restore callee's TOC > + > +#ifdef CONFIG_FUNCTION_GRAPH_TRACER > + stdu r1, -112(r1) > +.globl ftrace_graph_call > +ftrace_graph_call: > + b ftrace_graph_stub > +_GLOBAL(ftrace_graph_stub) > + addi r1, r1, 112 > +#endif > + > + mflr r0 // move this LR to CTR > + mtctr r0 > + > + ld r0,LRSAVE(r1) // restore callee's lr at _mcount site > + mtlr r0 > + bctr // jump after _mcount site > +#endif /* CC_USING_MPROFILE_KERNEL */ > _GLOBAL(ftrace_stub) > blr > #else > diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c > index 080c525..310137f 100644 > --- a/arch/powerpc/kernel/ftrace.c > +++ b/arch/powerpc/kernel/ftrace.c > @@ -61,8 +61,11 @@ ftrace_modify_code(unsigned long ip, unsigned int old, > unsigned int new) > return -EFAULT; > > /* Make sure it is what we expect it to be */ > - if (replaced != old) > + if (replaced != old) { > + pr_err("%p: replaced (%#x) != old (%#x)", > + (void *)ip, replaced, old); > return -EINVAL; > + } > > /* replace the text with the new text */ > if (patch_instruction((unsigned int *)ip, new)) > @@ -106,14 +109,16 @@ static int > __ftrace_make_nop(struct module *mod, > struct dyn_ftrace *rec, unsigned long addr) > { > - unsigned int op; > + unsigned int op, op0, op1, pop; > unsigned long entry, ptr; > unsigned long ip = rec->ip; > void *tramp; > > /* read where this goes */ > - if (probe_kernel_read(&op, (void *)ip, sizeof(int))) > + if (probe_kernel_read(&op, (void *)ip, sizeof(int))) { > + pr_err("Fetching opcode failed.\n"); > return -EFAULT; > + } > > /* Make sure that that this is still a 24bit jump */ > if (!is_bl_op(op)) { > @@ -158,10 +163,46 @@ __ftrace_make_nop(struct module *mod, > * > * Use a b +8 to jump over the load. > */ > - op = 0x48000008; /* b +8 */ > > - if (patch_instruction((unsigned int *)ip, op)) > + pop = 0x48000008; /* b +8 */ > + > + /* > + * Check what is in the next instruction. We can see ld r2,40(r1), but > + * on first pass after boot we will see mflr r0. > + */ > + if (probe_kernel_read(&op, (void *)(ip+4), MCOUNT_INSN_SIZE)) { > + pr_err("Fetching op failed.\n"); > + return -EFAULT; > + } > + > + if (op != 0xe8410028) { /* ld r2,STACK_OFFSET(r1) */ > + > + if (probe_kernel_read(&op0, (void *)(ip-8), MCOUNT_INSN_SIZE)) { > + pr_err("Fetching op0 failed.\n"); > + return -EFAULT; > + } > + > + if (probe_kernel_read(&op1, (void *)(ip-4), MCOUNT_INSN_SIZE)) { > + pr_err("Fetching op1 failed.\n"); > + return -EFAULT; > + } > + > + /* mflr r0 ; std r0,LRSAVE(r1) */ > + if (op0 != 0x7c0802a6 && op1 != 0xf8010010) { > + pr_err("Unexpected instructions around bl\n" > + "when enabling dynamic ftrace!\t" > + "(%08x,%08x,bl,%08x)\n", op0, op1, op); > + return -EINVAL; > + } > + > + /* When using -mkernel_profile there is no load to jump over */ > + pop = PPC_INST_NOP; > + } > + > + if (patch_instruction((unsigned int *)ip, pop)) { > + pr_err("Patching NOP failed.\n"); > return -EPERM; > + } > > return 0; > } > @@ -287,6 +328,13 @@ int ftrace_make_nop(struct module *mod, > > #ifdef CONFIG_MODULES > #ifdef CONFIG_PPC64 > +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, > + unsigned long addr) > +{ > + return ftrace_make_call(rec, addr); > +} > +#endif > static int > __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) > { > @@ -338,7 +386,7 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long > addr) > > return 0; > } > -#else > +#else /* !CONFIG_PPC64: */ > static int > __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) > { > diff --git a/arch/powerpc/kernel/module_64.c > b/arch/powerpc/kernel/module_64.c > index 0819ce7..9e6902f 100644 > --- a/arch/powerpc/kernel/module_64.c > +++ b/arch/powerpc/kernel/module_64.c > @@ -138,12 +138,25 @@ static u32 ppc64_stub_insns[] = { > 0x4e800420 /* bctr */ > }; > > +#ifdef CC_USING_MPROFILE_KERNEL > +/* In case of _mcount calls or dynamic ftracing, Do not save the > + * current callee's TOC (in R2) again into the original caller's stack > + * frame during this trampoline hop. The stack frame already holds > + * that of the original caller. _mcount and ftrace_caller will take > + * care of this TOC value themselves. > + */ > +#define SQUASH_TOC_SAVE_INSN(trampoline_addr) \ > + (((struct ppc64_stub_entry *)(trampoline_addr))->jump[2] = PPC_INST_NOP) > +#else > +#define SQUASH_TOC_SAVE_INSN(trampoline_addr) > +#endif > + > #ifdef CONFIG_DYNAMIC_FTRACE > > static u32 ppc64_stub_mask[] = { > 0xffff0000, > 0xffff0000, > - 0xffffffff, > + 0x00000000, > 0xffffffff, > #if !defined(_CALL_ELF) || _CALL_ELF != 2 > 0xffffffff, > @@ -170,6 +183,9 @@ bool is_module_trampoline(u32 *p) > if ((insna & mask) != (insnb & mask)) > return false; > } > + if (insns[2] != ppc64_stub_insns[2] && > + insns[2] != PPC_INST_NOP) > + return false; > > return true; > } > @@ -618,6 +634,9 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, > return -ENOENT; > if (!restore_r2((u32 *)location + 1, me)) > return -ENOEXEC; > + /* Squash the TOC saver for profiler calls */ > + if (!strcmp("_mcount", strtab+sym->st_name)) > + SQUASH_TOC_SAVE_INSN(value); > } else > value += local_entry_offset(sym); > > @@ -678,6 +697,10 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, > me->arch.tramp = stub_for_addr(sechdrs, > (unsigned long)ftrace_caller, > me); > + /* ftrace_caller will take care of the TOC; > + * do not clobber original caller's value. > + */ > + SQUASH_TOC_SAVE_INSN(me->arch.tramp); > #endif > > return 0; > -- > 1.8.5.6 > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev
On Thu, Nov 26, 2015 at 01:04:19PM +0300, Denis Kirjanov wrote: > On 11/25/15, Torsten Duwe <duwe@lst.de> wrote: > > --- a/arch/powerpc/kernel/entry_64.S > > +++ b/arch/powerpc/kernel/entry_64.S > Linux style for comments is the C89. Please update entry_64.S I might as well switch to asm-style comments. Anyway, thanks for the reminder. Torsten
On Thu, Nov 26, 2015 at 01:04:19PM +0300, Denis Kirjanov wrote: > > diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S > > index 8d56b16..3309dd8 100644 > > --- a/arch/powerpc/kernel/entry_64.S > > +++ b/arch/powerpc/kernel/entry_64.S > Linux style for comments is the C89. Please update entry_64.S Any other (planned) remarks or comments on the patch set? If not I'll make a 5th, hopefully final version. Torsten
On Tue, 2015-12-01 at 18:29 +0100, Torsten Duwe wrote: > On Thu, Nov 26, 2015 at 01:04:19PM +0300, Denis Kirjanov wrote: > > > diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S > > > index 8d56b16..3309dd8 100644 > > > --- a/arch/powerpc/kernel/entry_64.S > > > +++ b/arch/powerpc/kernel/entry_64.S > > Linux style for comments is the C89. Please update entry_64.S > > Any other (planned) remarks or comments on the patch set? > If not I'll make a 5th, hopefully final version. I (still) haven't had a chance to have a good look at it, but I won't this week anyway. So post v5 and hopefully I can review that and it will be perfect :) cheers
On Wed, Dec 02, 2015 at 09:18:05AM +1100, Michael Ellerman wrote: > > I (still) haven't had a chance to have a good look at it, but I won't this week > anyway. So post v5 and hopefully I can review that and it will be perfect :) The perfect v5 is there now, for 4 weeks minus the holiday season, and no further problems arose. Independently verified by Petr Mladek -- don't forget his high-level fix. Torsten
On Tue, 5 Jan 2016, Torsten Duwe wrote: > > I (still) haven't had a chance to have a good look at it, but I won't this week > > anyway. So post v5 and hopefully I can review that and it will be perfect :) > > The perfect v5 is there now, for 4 weeks minus the holiday season, and > no further problems arose. Independently verified by Petr Mladek -- > don't forget his high-level fix. Hi everybody, so what are the current plans with this one, please? Is this going through ppc tree, ftrace tree, or does it have issues that need to be worked on before merging? Thanks!
On Mon, 2016-01-18 at 23:22 +0100, Jiri Kosina wrote: > On Tue, 5 Jan 2016, Torsten Duwe wrote: > > > > I (still) haven't had a chance to have a good look at it, but I won't this week > > > anyway. So post v5 and hopefully I can review that and it will be perfect :) > > > > The perfect v5 is there now, for 4 weeks minus the holiday season, and > > no further problems arose. Independently verified by Petr Mladek -- > > don't forget his high-level fix. > > Hi everybody, > > so what are the current plans with this one, please? Is this going through > ppc tree, ftrace tree, or does it have issues that need to be worked on > before merging? Anton and I need to review it and then it will be merged via the powerpc tree. We just haven't had the spare cycles to do it. cheers
diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h index ef89b14..50ca758 100644 --- a/arch/powerpc/include/asm/ftrace.h +++ b/arch/powerpc/include/asm/ftrace.h @@ -46,6 +46,8 @@ extern void _mcount(void); #ifdef CONFIG_DYNAMIC_FTRACE +# define FTRACE_ADDR ((unsigned long)ftrace_caller) +# define FTRACE_REGS_ADDR FTRACE_ADDR static inline unsigned long ftrace_call_adjust(unsigned long addr) { /* reloction of mcount call site is the same as the address */ @@ -58,6 +60,9 @@ struct dyn_arch_ftrace { #endif /* CONFIG_DYNAMIC_FTRACE */ #endif /* __ASSEMBLY__ */ +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS +#define ARCH_SUPPORTS_FTRACE_OPS 1 +#endif #endif #if defined(CONFIG_FTRACE_SYSCALLS) && defined(CONFIG_PPC64) && !defined(__ASSEMBLY__) diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 8d56b16..3309dd8 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -1212,6 +1212,7 @@ _GLOBAL(_mcount) mtlr r0 bctr +#ifndef CC_USING_MPROFILE_KERNEL _GLOBAL_TOC(ftrace_caller) /* Taken from output of objdump from lib64/glibc */ mflr r3 @@ -1233,6 +1234,82 @@ _GLOBAL(ftrace_graph_stub) ld r0, 128(r1) mtlr r0 addi r1, r1, 112 +#else +_GLOBAL(ftrace_caller) +#if defined(_CALL_ELF) && _CALL_ELF == 2 + mflr r0 + bl 2f +2: mflr r12 + mtlr r0 + mr r0,r2 // save callee's TOC + addis r2,r12,(.TOC.-ftrace_caller-8)@ha + addi r2,r2,(.TOC.-ftrace_caller-8)@l +#else + mr r0,r2 +#endif + ld r12,LRSAVE(r1) // get caller's address + + stdu r1,-SWITCH_FRAME_SIZE(r1) + + std r12, _LINK(r1) + SAVE_8GPRS(0,r1) + std r0, 24(r1) // save TOC + SAVE_8GPRS(8,r1) + SAVE_8GPRS(16,r1) + SAVE_8GPRS(24,r1) + + addis r3,r2,function_trace_op@toc@ha + addi r3,r3,function_trace_op@toc@l + ld r5,0(r3) + + mflr r3 + std r3, _NIP(r1) + std r3, 16(r1) + subi r3, r3, MCOUNT_INSN_SIZE + mfmsr r4 + std r4, _MSR(r1) + mfctr r4 + std r4, _CTR(r1) + mfxer r4 + std r4, _XER(r1) + mr r4, r12 + addi r6, r1 ,STACK_FRAME_OVERHEAD + +.globl ftrace_call +ftrace_call: + bl ftrace_stub + nop + + ld r3, _NIP(r1) + mtlr r3 + + REST_8GPRS(0,r1) + REST_8GPRS(8,r1) + REST_8GPRS(16,r1) + REST_8GPRS(24,r1) + + addi r1, r1, SWITCH_FRAME_SIZE + + ld r12, LRSAVE(r1) // get caller's address + mtlr r12 + mr r2,r0 // restore callee's TOC + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + stdu r1, -112(r1) +.globl ftrace_graph_call +ftrace_graph_call: + b ftrace_graph_stub +_GLOBAL(ftrace_graph_stub) + addi r1, r1, 112 +#endif + + mflr r0 // move this LR to CTR + mtctr r0 + + ld r0,LRSAVE(r1) // restore callee's lr at _mcount site + mtlr r0 + bctr // jump after _mcount site +#endif /* CC_USING_MPROFILE_KERNEL */ _GLOBAL(ftrace_stub) blr #else diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c index 080c525..310137f 100644 --- a/arch/powerpc/kernel/ftrace.c +++ b/arch/powerpc/kernel/ftrace.c @@ -61,8 +61,11 @@ ftrace_modify_code(unsigned long ip, unsigned int old, unsigned int new) return -EFAULT; /* Make sure it is what we expect it to be */ - if (replaced != old) + if (replaced != old) { + pr_err("%p: replaced (%#x) != old (%#x)", + (void *)ip, replaced, old); return -EINVAL; + } /* replace the text with the new text */ if (patch_instruction((unsigned int *)ip, new)) @@ -106,14 +109,16 @@ static int __ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) { - unsigned int op; + unsigned int op, op0, op1, pop; unsigned long entry, ptr; unsigned long ip = rec->ip; void *tramp; /* read where this goes */ - if (probe_kernel_read(&op, (void *)ip, sizeof(int))) + if (probe_kernel_read(&op, (void *)ip, sizeof(int))) { + pr_err("Fetching opcode failed.\n"); return -EFAULT; + } /* Make sure that that this is still a 24bit jump */ if (!is_bl_op(op)) { @@ -158,10 +163,46 @@ __ftrace_make_nop(struct module *mod, * * Use a b +8 to jump over the load. */ - op = 0x48000008; /* b +8 */ - if (patch_instruction((unsigned int *)ip, op)) + pop = 0x48000008; /* b +8 */ + + /* + * Check what is in the next instruction. We can see ld r2,40(r1), but + * on first pass after boot we will see mflr r0. + */ + if (probe_kernel_read(&op, (void *)(ip+4), MCOUNT_INSN_SIZE)) { + pr_err("Fetching op failed.\n"); + return -EFAULT; + } + + if (op != 0xe8410028) { /* ld r2,STACK_OFFSET(r1) */ + + if (probe_kernel_read(&op0, (void *)(ip-8), MCOUNT_INSN_SIZE)) { + pr_err("Fetching op0 failed.\n"); + return -EFAULT; + } + + if (probe_kernel_read(&op1, (void *)(ip-4), MCOUNT_INSN_SIZE)) { + pr_err("Fetching op1 failed.\n"); + return -EFAULT; + } + + /* mflr r0 ; std r0,LRSAVE(r1) */ + if (op0 != 0x7c0802a6 && op1 != 0xf8010010) { + pr_err("Unexpected instructions around bl\n" + "when enabling dynamic ftrace!\t" + "(%08x,%08x,bl,%08x)\n", op0, op1, op); + return -EINVAL; + } + + /* When using -mkernel_profile there is no load to jump over */ + pop = PPC_INST_NOP; + } + + if (patch_instruction((unsigned int *)ip, pop)) { + pr_err("Patching NOP failed.\n"); return -EPERM; + } return 0; } @@ -287,6 +328,13 @@ int ftrace_make_nop(struct module *mod, #ifdef CONFIG_MODULES #ifdef CONFIG_PPC64 +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, + unsigned long addr) +{ + return ftrace_make_call(rec, addr); +} +#endif static int __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) { @@ -338,7 +386,7 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) return 0; } -#else +#else /* !CONFIG_PPC64: */ static int __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) { diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c index 0819ce7..9e6902f 100644 --- a/arch/powerpc/kernel/module_64.c +++ b/arch/powerpc/kernel/module_64.c @@ -138,12 +138,25 @@ static u32 ppc64_stub_insns[] = { 0x4e800420 /* bctr */ }; +#ifdef CC_USING_MPROFILE_KERNEL +/* In case of _mcount calls or dynamic ftracing, Do not save the + * current callee's TOC (in R2) again into the original caller's stack + * frame during this trampoline hop. The stack frame already holds + * that of the original caller. _mcount and ftrace_caller will take + * care of this TOC value themselves. + */ +#define SQUASH_TOC_SAVE_INSN(trampoline_addr) \ + (((struct ppc64_stub_entry *)(trampoline_addr))->jump[2] = PPC_INST_NOP) +#else +#define SQUASH_TOC_SAVE_INSN(trampoline_addr) +#endif + #ifdef CONFIG_DYNAMIC_FTRACE static u32 ppc64_stub_mask[] = { 0xffff0000, 0xffff0000, - 0xffffffff, + 0x00000000, 0xffffffff, #if !defined(_CALL_ELF) || _CALL_ELF != 2 0xffffffff, @@ -170,6 +183,9 @@ bool is_module_trampoline(u32 *p) if ((insna & mask) != (insnb & mask)) return false; } + if (insns[2] != ppc64_stub_insns[2] && + insns[2] != PPC_INST_NOP) + return false; return true; } @@ -618,6 +634,9 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, return -ENOENT; if (!restore_r2((u32 *)location + 1, me)) return -ENOEXEC; + /* Squash the TOC saver for profiler calls */ + if (!strcmp("_mcount", strtab+sym->st_name)) + SQUASH_TOC_SAVE_INSN(value); } else value += local_entry_offset(sym); @@ -678,6 +697,10 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, me->arch.tramp = stub_for_addr(sechdrs, (unsigned long)ftrace_caller, me); + /* ftrace_caller will take care of the TOC; + * do not clobber original caller's value. + */ + SQUASH_TOC_SAVE_INSN(me->arch.tramp); #endif return 0;
Implement FTRACE_WITH_REGS for powerpc64, on ELF ABI v2. Initial work started by Vojtech Pavlik, used with permission. * arch/powerpc/kernel/entry_64.S: - Implement an effective ftrace_caller that works from within the kernel binary as well as from modules. * arch/powerpc/kernel/ftrace.c: - be prepared to deal with ppc64 ELF ABI v2, especially calls to _mcount that result from gcc -mprofile-kernel - a little more error verbosity * arch/powerpc/kernel/module_64.c: - do not save the TOC pointer on the trampoline when the destination is ftrace_caller. This trampoline jump happens from a function prologue before a new stack frame is set up, so bad things may happen otherwise... - relax is_module_trampoline() to recognise the modified trampoline. Signed-off-by: Torsten Duwe <duwe@suse.de> --- arch/powerpc/include/asm/ftrace.h | 5 +++ arch/powerpc/kernel/entry_64.S | 77 +++++++++++++++++++++++++++++++++++++++ arch/powerpc/kernel/ftrace.c | 60 +++++++++++++++++++++++++++--- arch/powerpc/kernel/module_64.c | 25 ++++++++++++- 4 files changed, 160 insertions(+), 7 deletions(-)