| Message ID | 8843d65ac0878232433573d10ebee30457748624.1645096227.git.naveen.n.rao@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | powerpc/ftrace: Reserve instructions from function entry for ftrace | expand |
Hi "Naveen,
I love your patch! Perhaps something to improve:
[auto build test WARNING on 1b43a74f255c5c00db25a5fedfd75ca0dc029022]
url: https://github.com/0day-ci/linux/commits/Naveen-N-Rao/powerpc-ftrace-Reserve-instructions-from-function-entry-for-ftrace/20220217-200314
base: 1b43a74f255c5c00db25a5fedfd75ca0dc029022
config: powerpc-allyesconfig (https://download.01.org/0day-ci/archive/20220218/202202180014.IWuzQ9al-lkp@intel.com/config)
compiler: powerpc-linux-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/0day-ci/linux/commit/6a1891335e377e5def312e7c182aef676f04c926
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Naveen-N-Rao/powerpc-ftrace-Reserve-instructions-from-function-entry-for-ftrace/20220217-200314
git checkout 6a1891335e377e5def312e7c182aef676f04c926
# save the config file to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=powerpc SHELL=/bin/bash arch/powerpc/kernel/trace/
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
All warnings (new ones prefixed by >>):
>> arch/powerpc/kernel/trace/ftrace.c:504:5: warning: no previous prototype for 'ftrace_location_get_offset' [-Wmissing-prototypes]
504 | int ftrace_location_get_offset(const struct dyn_ftrace *rec)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
vim +/ftrace_location_get_offset +504 arch/powerpc/kernel/trace/ftrace.c
502
503 #if defined(CONFIG_MPROFILE_KERNEL) || defined(CONFIG_PPC32)
> 504 int ftrace_location_get_offset(const struct dyn_ftrace *rec)
505 {
506 if (IS_ENABLED(CONFIG_MPROFILE_KERNEL))
507 /*
508 * On ppc64le with -mprofile-kernel, function entry can have:
509 * addis r2, r12, M
510 * addi r2, r2, N
511 * mflr r0
512 * bl _mcount
513 *
514 * The first two instructions are for TOC setup and represent the global entry
515 * point for cross-module calls, and may be missing if the function is never called
516 * from other modules.
517 */
518 return ((unsigned long)rec->arch.mod & 0x1) ? FUNC_MCOUNT_OFFSET_PPC64_GEP :
519 FUNC_MCOUNT_OFFSET_PPC64_LEP;
520 else
521 /*
522 * On ppc32, function entry always has:
523 * mflr r0
524 * stw r0, 4(r1)
525 * bl _mcount
526 */
527 return FUNC_MCOUNT_OFFSET_PPC32;
528 }
529
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
Hi Naveen, On Thu, 17 Feb 2022 17:06:23 +0530 "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote: > On some architectures, enabling function tracing results in multiple > instructions being emitted at function entry. As an example, on > powerpc64 with -mprofile-kernel, two instructions are emitted at > function entry: > mflr r0 > bl _mcount > > It is desirable to nop out both these instructions when ftrace is not > active. For that purpose, it is essential to mark both these > instructions as belonging to ftrace so that other kernel subsystems > (such as kprobes) do not modify these instructions. Indeed, kprobes must handle this. However, to keep consistency of kprobes usage with/without CONFIG_FUNCTION_TRACER, I think KPROBES_ON_FTRACE should handle these instructions are virutal single instruction. More specifically, it should allow user to put a kprobe on 'mflr r0' address and the kprobes on 'bl _mcount' should return -EILSEQ. (because it is not an instruction boundary.) And the kprobe's ftrace handler temporarily modifies the instruction pointer to the address of 'mflr'. Thank you, > > Add support for this by allowing architectures to override > ftrace_cmp_recs() and to match against address ranges over and above a > single MCOUNT_INSN_SIZE. > > For powerpc32, we mark the two instructions preceding the call to > _mcount() as belonging to ftrace. > > For powerpc64, an additional aspect to consider is that functions can > have a global entry point for setting up the TOC when invoked from other > modules. If present, global entry point always involves two instructions > (addis/lis and addi). To handle this, we provide a custom > ftrace_init_nop() for powerpc64 where we identify functions having a > global entry point and record this information in the LSB of > dyn_ftrace->arch.mod. This information is used in ftrace_cmp_recs() to > reserve instructions from the global entry point. > > Suggested-by: Steven Rostedt <rostedt@goodmis.org> > Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> > --- > arch/powerpc/include/asm/ftrace.h | 15 ++++ > arch/powerpc/kernel/trace/ftrace.c | 110 ++++++++++++++++++++++++++--- > kernel/trace/ftrace.c | 2 + > 3 files changed, 117 insertions(+), 10 deletions(-) > > diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h > index debe8c4f706260..8eb3235831633d 100644 > --- a/arch/powerpc/include/asm/ftrace.h > +++ b/arch/powerpc/include/asm/ftrace.h > @@ -59,6 +59,21 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr) > struct dyn_arch_ftrace { > struct module *mod; > }; > + > +struct dyn_ftrace; > +struct module *ftrace_mod_addr_get(struct dyn_ftrace *rec); > +void ftrace_mod_addr_set(struct dyn_ftrace *rec, struct module *mod); > + > +#ifdef CONFIG_MPROFILE_KERNEL > +int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec); > +#define ftrace_init_nop ftrace_init_nop > +#endif > + > +#if defined(CONFIG_MPROFILE_KERNEL) || defined(CONFIG_PPC32) > +int ftrace_cmp_recs(const void *a, const void *b); > +#define ftrace_cmp_recs ftrace_cmp_recs > +#endif > + > #endif /* __ASSEMBLY__ */ > > #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c > index 80b6285769f27c..11ce9296ce3cf2 100644 > --- a/arch/powerpc/kernel/trace/ftrace.c > +++ b/arch/powerpc/kernel/trace/ftrace.c > @@ -428,21 +428,21 @@ int ftrace_make_nop(struct module *mod, > * We should either already have a pointer to the module > * or it has been passed in. > */ > - if (!rec->arch.mod) { > + if (!ftrace_mod_addr_get(rec)) { > if (!mod) { > pr_err("No module loaded addr=%lx\n", addr); > return -EFAULT; > } > - rec->arch.mod = mod; > + ftrace_mod_addr_set(rec, mod); > } else if (mod) { > - if (mod != rec->arch.mod) { > + if (mod != ftrace_mod_addr_get(rec)) { > pr_err("Record mod %p not equal to passed in mod %p\n", > - rec->arch.mod, mod); > + ftrace_mod_addr_get(rec), mod); > return -EINVAL; > } > /* nothing to do if mod == rec->arch.mod */ > } else > - mod = rec->arch.mod; > + mod = ftrace_mod_addr_get(rec); > > return __ftrace_make_nop(mod, rec, addr); > #else > @@ -451,6 +451,96 @@ int ftrace_make_nop(struct module *mod, > #endif /* CONFIG_MODULES */ > } > > +#define FUNC_MCOUNT_OFFSET_PPC32 8 > +#define FUNC_MCOUNT_OFFSET_PPC64_LEP 4 > +#define FUNC_MCOUNT_OFFSET_PPC64_GEP 12 > + > +#ifdef CONFIG_MPROFILE_KERNEL > +struct module *ftrace_mod_addr_get(struct dyn_ftrace *rec) > +{ > + return (struct module *)((unsigned long)rec->arch.mod & ~0x1); > +} > + > +void ftrace_mod_addr_set(struct dyn_ftrace *rec, struct module *mod) > +{ > + rec->arch.mod = (struct module *)(((unsigned long)rec->arch.mod & 0x1) | (unsigned long)mod); > +} > + > +int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec) > +{ > + unsigned long offset, ip = rec->ip; > + ppc_inst_t op1, op2; > + int ret; > + > + if (!kallsyms_lookup_size_offset(rec->ip, NULL, &offset) || > + (offset != FUNC_MCOUNT_OFFSET_PPC64_GEP && offset != FUNC_MCOUNT_OFFSET_PPC64_LEP)) { > + ip -= FUNC_MCOUNT_OFFSET_PPC64_GEP; > + ret = copy_inst_from_kernel_nofault(&op1, (void *)ip); > + ret |= copy_inst_from_kernel_nofault(&op2, (void *)(ip + MCOUNT_INSN_SIZE)); > + if (!ret && > + ((ppc_inst_val(op1) & 0xffff0000) == PPC_RAW_LIS(_R2, 0) || > + (ppc_inst_val(op1) & 0xffff0000) == PPC_RAW_ADDIS(_R2, _R12, 0)) && > + (ppc_inst_val(op2) & 0xffff0000) == PPC_RAW_ADDI(_R2, _R2, 0)) > + ftrace_mod_addr_set(rec, (struct module *)1); > + } else if (offset == FUNC_MCOUNT_OFFSET_PPC64_GEP) { > + ftrace_mod_addr_set(rec, (struct module *)1); > + } > + > + return ftrace_make_nop(mod, rec, MCOUNT_ADDR); > +} > +#else > +struct module *ftrace_mod_addr_get(struct dyn_ftrace *rec) > +{ > + return rec->arch.mod; > +} > + > +void ftrace_mod_addr_set(struct dyn_ftrace *rec, struct module *mod) > +{ > + rec->arch.mod = mod; > +} > +#endif /* CONFIG_MPROFILE_KERNEL */ > + > +#if defined(CONFIG_MPROFILE_KERNEL) || defined(CONFIG_PPC32) > +int ftrace_location_get_offset(const struct dyn_ftrace *rec) > +{ > + if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) > + /* > + * On ppc64le with -mprofile-kernel, function entry can have: > + * addis r2, r12, M > + * addi r2, r2, N > + * mflr r0 > + * bl _mcount > + * > + * The first two instructions are for TOC setup and represent the global entry > + * point for cross-module calls, and may be missing if the function is never called > + * from other modules. > + */ > + return ((unsigned long)rec->arch.mod & 0x1) ? FUNC_MCOUNT_OFFSET_PPC64_GEP : > + FUNC_MCOUNT_OFFSET_PPC64_LEP; > + else > + /* > + * On ppc32, function entry always has: > + * mflr r0 > + * stw r0, 4(r1) > + * bl _mcount > + */ > + return FUNC_MCOUNT_OFFSET_PPC32; > +} > + > +int ftrace_cmp_recs(const void *a, const void *b) > +{ > + const struct dyn_ftrace *key = a; > + const struct dyn_ftrace *rec = b; > + int offset = ftrace_location_get_offset(rec); > + > + if (key->flags < rec->ip - offset) > + return -1; > + if (key->ip >= rec->ip + MCOUNT_INSN_SIZE) > + return 1; > + return 0; > +} > +#endif > + > #ifdef CONFIG_MODULES > #ifdef CONFIG_PPC64 > /* > @@ -494,7 +584,7 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) > ppc_inst_t instr; > void *ip = (void *)rec->ip; > unsigned long entry, ptr, tramp; > - struct module *mod = rec->arch.mod; > + struct module *mod = ftrace_mod_addr_get(rec); > > /* read where this goes */ > if (copy_inst_from_kernel_nofault(op, ip)) > @@ -561,7 +651,7 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) > int err; > ppc_inst_t op; > u32 *ip = (u32 *)rec->ip; > - struct module *mod = rec->arch.mod; > + struct module *mod = ftrace_mod_addr_get(rec); > unsigned long tramp; > > /* read where this goes */ > @@ -678,7 +768,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) > * Being that we are converting from nop, it had better > * already have a module defined. > */ > - if (!rec->arch.mod) { > + if (!ftrace_mod_addr_get(rec)) { > pr_err("No module loaded\n"); > return -EINVAL; > } > @@ -699,7 +789,7 @@ __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, > ppc_inst_t op; > unsigned long ip = rec->ip; > unsigned long entry, ptr, tramp; > - struct module *mod = rec->arch.mod; > + struct module *mod = ftrace_mod_addr_get(rec); > > /* If we never set up ftrace trampolines, then bail */ > if (!mod->arch.tramp || !mod->arch.tramp_regs) { > @@ -814,7 +904,7 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, > /* > * Out of range jumps are called from modules. > */ > - if (!rec->arch.mod) { > + if (!ftrace_mod_addr_get(rec)) { > pr_err("No module loaded\n"); > return -EINVAL; > } > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index f9feb197b2daaf..68f20cf34b0c47 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -1510,6 +1510,7 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs) > } > > > +#ifndef ftrace_cmp_recs > static int ftrace_cmp_recs(const void *a, const void *b) > { > const struct dyn_ftrace *key = a; > @@ -1521,6 +1522,7 @@ static int ftrace_cmp_recs(const void *a, const void *b) > return 1; > return 0; > } > +#endif > > static struct dyn_ftrace *lookup_rec(unsigned long start, unsigned long end) > { > -- > 2.35.1 >
diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h index debe8c4f706260..8eb3235831633d 100644 --- a/arch/powerpc/include/asm/ftrace.h +++ b/arch/powerpc/include/asm/ftrace.h @@ -59,6 +59,21 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr) struct dyn_arch_ftrace { struct module *mod; }; + +struct dyn_ftrace; +struct module *ftrace_mod_addr_get(struct dyn_ftrace *rec); +void ftrace_mod_addr_set(struct dyn_ftrace *rec, struct module *mod); + +#ifdef CONFIG_MPROFILE_KERNEL +int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec); +#define ftrace_init_nop ftrace_init_nop +#endif + +#if defined(CONFIG_MPROFILE_KERNEL) || defined(CONFIG_PPC32) +int ftrace_cmp_recs(const void *a, const void *b); +#define ftrace_cmp_recs ftrace_cmp_recs +#endif + #endif /* __ASSEMBLY__ */ #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c index 80b6285769f27c..11ce9296ce3cf2 100644 --- a/arch/powerpc/kernel/trace/ftrace.c +++ b/arch/powerpc/kernel/trace/ftrace.c @@ -428,21 +428,21 @@ int ftrace_make_nop(struct module *mod, * We should either already have a pointer to the module * or it has been passed in. */ - if (!rec->arch.mod) { + if (!ftrace_mod_addr_get(rec)) { if (!mod) { pr_err("No module loaded addr=%lx\n", addr); return -EFAULT; } - rec->arch.mod = mod; + ftrace_mod_addr_set(rec, mod); } else if (mod) { - if (mod != rec->arch.mod) { + if (mod != ftrace_mod_addr_get(rec)) { pr_err("Record mod %p not equal to passed in mod %p\n", - rec->arch.mod, mod); + ftrace_mod_addr_get(rec), mod); return -EINVAL; } /* nothing to do if mod == rec->arch.mod */ } else - mod = rec->arch.mod; + mod = ftrace_mod_addr_get(rec); return __ftrace_make_nop(mod, rec, addr); #else @@ -451,6 +451,96 @@ int ftrace_make_nop(struct module *mod, #endif /* CONFIG_MODULES */ } +#define FUNC_MCOUNT_OFFSET_PPC32 8 +#define FUNC_MCOUNT_OFFSET_PPC64_LEP 4 +#define FUNC_MCOUNT_OFFSET_PPC64_GEP 12 + +#ifdef CONFIG_MPROFILE_KERNEL +struct module *ftrace_mod_addr_get(struct dyn_ftrace *rec) +{ + return (struct module *)((unsigned long)rec->arch.mod & ~0x1); +} + +void ftrace_mod_addr_set(struct dyn_ftrace *rec, struct module *mod) +{ + rec->arch.mod = (struct module *)(((unsigned long)rec->arch.mod & 0x1) | (unsigned long)mod); +} + +int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec) +{ + unsigned long offset, ip = rec->ip; + ppc_inst_t op1, op2; + int ret; + + if (!kallsyms_lookup_size_offset(rec->ip, NULL, &offset) || + (offset != FUNC_MCOUNT_OFFSET_PPC64_GEP && offset != FUNC_MCOUNT_OFFSET_PPC64_LEP)) { + ip -= FUNC_MCOUNT_OFFSET_PPC64_GEP; + ret = copy_inst_from_kernel_nofault(&op1, (void *)ip); + ret |= copy_inst_from_kernel_nofault(&op2, (void *)(ip + MCOUNT_INSN_SIZE)); + if (!ret && + ((ppc_inst_val(op1) & 0xffff0000) == PPC_RAW_LIS(_R2, 0) || + (ppc_inst_val(op1) & 0xffff0000) == PPC_RAW_ADDIS(_R2, _R12, 0)) && + (ppc_inst_val(op2) & 0xffff0000) == PPC_RAW_ADDI(_R2, _R2, 0)) + ftrace_mod_addr_set(rec, (struct module *)1); + } else if (offset == FUNC_MCOUNT_OFFSET_PPC64_GEP) { + ftrace_mod_addr_set(rec, (struct module *)1); + } + + return ftrace_make_nop(mod, rec, MCOUNT_ADDR); +} +#else +struct module *ftrace_mod_addr_get(struct dyn_ftrace *rec) +{ + return rec->arch.mod; +} + +void ftrace_mod_addr_set(struct dyn_ftrace *rec, struct module *mod) +{ + rec->arch.mod = mod; +} +#endif /* CONFIG_MPROFILE_KERNEL */ + +#if defined(CONFIG_MPROFILE_KERNEL) || defined(CONFIG_PPC32) +int ftrace_location_get_offset(const struct dyn_ftrace *rec) +{ + if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) + /* + * On ppc64le with -mprofile-kernel, function entry can have: + * addis r2, r12, M + * addi r2, r2, N + * mflr r0 + * bl _mcount + * + * The first two instructions are for TOC setup and represent the global entry + * point for cross-module calls, and may be missing if the function is never called + * from other modules. + */ + return ((unsigned long)rec->arch.mod & 0x1) ? FUNC_MCOUNT_OFFSET_PPC64_GEP : + FUNC_MCOUNT_OFFSET_PPC64_LEP; + else + /* + * On ppc32, function entry always has: + * mflr r0 + * stw r0, 4(r1) + * bl _mcount + */ + return FUNC_MCOUNT_OFFSET_PPC32; +} + +int ftrace_cmp_recs(const void *a, const void *b) +{ + const struct dyn_ftrace *key = a; + const struct dyn_ftrace *rec = b; + int offset = ftrace_location_get_offset(rec); + + if (key->flags < rec->ip - offset) + return -1; + if (key->ip >= rec->ip + MCOUNT_INSN_SIZE) + return 1; + return 0; +} +#endif + #ifdef CONFIG_MODULES #ifdef CONFIG_PPC64 /* @@ -494,7 +584,7 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) ppc_inst_t instr; void *ip = (void *)rec->ip; unsigned long entry, ptr, tramp; - struct module *mod = rec->arch.mod; + struct module *mod = ftrace_mod_addr_get(rec); /* read where this goes */ if (copy_inst_from_kernel_nofault(op, ip)) @@ -561,7 +651,7 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) int err; ppc_inst_t op; u32 *ip = (u32 *)rec->ip; - struct module *mod = rec->arch.mod; + struct module *mod = ftrace_mod_addr_get(rec); unsigned long tramp; /* read where this goes */ @@ -678,7 +768,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) * Being that we are converting from nop, it had better * already have a module defined. */ - if (!rec->arch.mod) { + if (!ftrace_mod_addr_get(rec)) { pr_err("No module loaded\n"); return -EINVAL; } @@ -699,7 +789,7 @@ __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, ppc_inst_t op; unsigned long ip = rec->ip; unsigned long entry, ptr, tramp; - struct module *mod = rec->arch.mod; + struct module *mod = ftrace_mod_addr_get(rec); /* If we never set up ftrace trampolines, then bail */ if (!mod->arch.tramp || !mod->arch.tramp_regs) { @@ -814,7 +904,7 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, /* * Out of range jumps are called from modules. */ - if (!rec->arch.mod) { + if (!ftrace_mod_addr_get(rec)) { pr_err("No module loaded\n"); return -EINVAL; } diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index f9feb197b2daaf..68f20cf34b0c47 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1510,6 +1510,7 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs) } +#ifndef ftrace_cmp_recs static int ftrace_cmp_recs(const void *a, const void *b) { const struct dyn_ftrace *key = a; @@ -1521,6 +1522,7 @@ static int ftrace_cmp_recs(const void *a, const void *b) return 1; return 0; } +#endif static struct dyn_ftrace *lookup_rec(unsigned long start, unsigned long end) {
On some architectures, enabling function tracing results in multiple instructions being emitted at function entry. As an example, on powerpc64 with -mprofile-kernel, two instructions are emitted at function entry: mflr r0 bl _mcount It is desirable to nop out both these instructions when ftrace is not active. For that purpose, it is essential to mark both these instructions as belonging to ftrace so that other kernel subsystems (such as kprobes) do not modify these instructions. Add support for this by allowing architectures to override ftrace_cmp_recs() and to match against address ranges over and above a single MCOUNT_INSN_SIZE. For powerpc32, we mark the two instructions preceding the call to _mcount() as belonging to ftrace. For powerpc64, an additional aspect to consider is that functions can have a global entry point for setting up the TOC when invoked from other modules. If present, global entry point always involves two instructions (addis/lis and addi). To handle this, we provide a custom ftrace_init_nop() for powerpc64 where we identify functions having a global entry point and record this information in the LSB of dyn_ftrace->arch.mod. This information is used in ftrace_cmp_recs() to reserve instructions from the global entry point. Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> --- arch/powerpc/include/asm/ftrace.h | 15 ++++ arch/powerpc/kernel/trace/ftrace.c | 110 ++++++++++++++++++++++++++--- kernel/trace/ftrace.c | 2 + 3 files changed, 117 insertions(+), 10 deletions(-)