| Message ID | f373684081e8e98be09b7f44d2d93069768324dc.1687166935.git.naveen@kernel.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | cc93b9233230312a8a905fabd590c405d60f9edd |
| Headers | show |
| Series | powerpc/ftrace: refactor and add support for -fpatchable-function-entry | expand |
Le 19/06/2023 à 11:47, Naveen N Rao a écrit : > Currently, we validate instructions around the ftrace location every > time we have to enable/disable ftrace. Introduce ftrace_init_nop() to > instead perform all the validation during ftrace initialization. This > allows us to simply patch the necessary instructions during > enabling/disabling ftrace. > > Signed-off-by: Naveen N Rao <naveen@kernel.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> > --- > arch/powerpc/include/asm/ftrace.h | 6 +++ > arch/powerpc/kernel/trace/ftrace.c | 71 ++++++++++++++++++++++++++++++ > 2 files changed, 77 insertions(+) > > diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h > index 702aaf2efa966c..ef9f0b97670d1c 100644 > --- a/arch/powerpc/include/asm/ftrace.h > +++ b/arch/powerpc/include/asm/ftrace.h > @@ -29,11 +29,17 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr) > unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip, > unsigned long sp); > > +struct module; > +struct dyn_ftrace; > struct dyn_arch_ftrace { > struct module *mod; > }; > > #ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS > +#define ftrace_need_init_nop() (true) > +int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec); > +#define ftrace_init_nop ftrace_init_nop > + > struct ftrace_regs { > struct pt_regs regs; > }; > diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c > index 278bf8e52b6e89..98bd099c428ee0 100644 > --- a/arch/powerpc/kernel/trace/ftrace.c > +++ b/arch/powerpc/kernel/trace/ftrace.c > @@ -31,6 +31,16 @@ > #define NUM_FTRACE_TRAMPS 2 > static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS]; > > +static ppc_inst_t ftrace_create_branch_inst(unsigned long ip, unsigned long addr, int link) > +{ > + ppc_inst_t op; > + > + WARN_ON(!is_offset_in_branch_range(addr - ip)); > + create_branch(&op, (u32 *)ip, addr, link ? BRANCH_SET_LINK : 0); > + > + return op; > +} > + > static ppc_inst_t > ftrace_call_replace(unsigned long ip, unsigned long addr, int link) > { > @@ -597,6 +607,67 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, > } > #endif > > +int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec) > +{ > + unsigned long addr, ip = rec->ip; > + ppc_inst_t old, new; > + int ret = 0; > + > + /* Verify instructions surrounding the ftrace location */ > + if (IS_ENABLED(CONFIG_PPC32)) { > + /* Expected sequence: 'mflr r0', 'stw r0,4(r1)', 'bl _mcount' */ > + ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0))); > + if (!ret) > + ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_STW(_R0, _R1, 4))); > + } else if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) { > + /* Expected sequence: 'mflr r0', ['std r0,16(r1)'], 'bl _mcount' */ > + ret = ftrace_read_inst(ip - 4, &old); > + if (!ret && !ppc_inst_equal(old, ppc_inst(PPC_RAW_MFLR(_R0)))) { > + ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0))); > + ret |= ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_STD(_R0, _R1, 16))); > + } > + } else { > + return -EINVAL; > + } > + > + if (ret) > + return ret; > + > + if (!core_kernel_text(ip)) { > + if (!mod) { > + pr_err("0x%lx: No module provided for non-kernel address\n", ip); > + return -EFAULT; > + } > + rec->arch.mod = mod; > + } > + > + /* Nop-out the ftrace location */ > + new = ppc_inst(PPC_RAW_NOP()); > + addr = MCOUNT_ADDR; > + if (is_offset_in_branch_range(addr - ip)) { > + /* Within range */ > + old = ftrace_create_branch_inst(ip, addr, 1); > + ret = ftrace_modify_code(ip, old, new); > + } else if (core_kernel_text(ip) || (IS_ENABLED(CONFIG_MODULES) && mod)) { > + /* > + * We would be branching to a linker-generated stub, or to the module _mcount > + * stub. Let's just confirm we have a 'bl' here. > + */ > + ret = ftrace_read_inst(ip, &old); > + if (ret) > + return ret; > + if (!is_bl_op(old)) { > + pr_err("0x%lx: expected (bl) != found (%08lx)\n", ip, ppc_inst_as_ulong(old)); > + return -EINVAL; > + } > + ret = patch_instruction((u32 *)ip, new); > + } else { > + return -EINVAL; > + } > + > + return ret; > +} > + > int ftrace_update_ftrace_func(ftrace_func_t func) > { > unsigned long ip = (unsigned long)(&ftrace_call);
diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h index 702aaf2efa966c..ef9f0b97670d1c 100644 --- a/arch/powerpc/include/asm/ftrace.h +++ b/arch/powerpc/include/asm/ftrace.h @@ -29,11 +29,17 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr) unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp); +struct module; +struct dyn_ftrace; struct dyn_arch_ftrace { struct module *mod; }; #ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS +#define ftrace_need_init_nop() (true) +int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec); +#define ftrace_init_nop ftrace_init_nop + struct ftrace_regs { struct pt_regs regs; }; diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c index 278bf8e52b6e89..98bd099c428ee0 100644 --- a/arch/powerpc/kernel/trace/ftrace.c +++ b/arch/powerpc/kernel/trace/ftrace.c @@ -31,6 +31,16 @@ #define NUM_FTRACE_TRAMPS 2 static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS]; +static ppc_inst_t ftrace_create_branch_inst(unsigned long ip, unsigned long addr, int link) +{ + ppc_inst_t op; + + WARN_ON(!is_offset_in_branch_range(addr - ip)); + create_branch(&op, (u32 *)ip, addr, link ? BRANCH_SET_LINK : 0); + + return op; +} + static ppc_inst_t ftrace_call_replace(unsigned long ip, unsigned long addr, int link) { @@ -597,6 +607,67 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, } #endif +int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec) +{ + unsigned long addr, ip = rec->ip; + ppc_inst_t old, new; + int ret = 0; + + /* Verify instructions surrounding the ftrace location */ + if (IS_ENABLED(CONFIG_PPC32)) { + /* Expected sequence: 'mflr r0', 'stw r0,4(r1)', 'bl _mcount' */ + ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0))); + if (!ret) + ret = ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_STW(_R0, _R1, 4))); + } else if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) { + /* Expected sequence: 'mflr r0', ['std r0,16(r1)'], 'bl _mcount' */ + ret = ftrace_read_inst(ip - 4, &old); + if (!ret && !ppc_inst_equal(old, ppc_inst(PPC_RAW_MFLR(_R0)))) { + ret = ftrace_validate_inst(ip - 8, ppc_inst(PPC_RAW_MFLR(_R0))); + ret |= ftrace_validate_inst(ip - 4, ppc_inst(PPC_RAW_STD(_R0, _R1, 16))); + } + } else { + return -EINVAL; + } + + if (ret) + return ret; + + if (!core_kernel_text(ip)) { + if (!mod) { + pr_err("0x%lx: No module provided for non-kernel address\n", ip); + return -EFAULT; + } + rec->arch.mod = mod; + } + + /* Nop-out the ftrace location */ + new = ppc_inst(PPC_RAW_NOP()); + addr = MCOUNT_ADDR; + if (is_offset_in_branch_range(addr - ip)) { + /* Within range */ + old = ftrace_create_branch_inst(ip, addr, 1); + ret = ftrace_modify_code(ip, old, new); + } else if (core_kernel_text(ip) || (IS_ENABLED(CONFIG_MODULES) && mod)) { + /* + * We would be branching to a linker-generated stub, or to the module _mcount + * stub. Let's just confirm we have a 'bl' here. + */ + ret = ftrace_read_inst(ip, &old); + if (ret) + return ret; + if (!is_bl_op(old)) { + pr_err("0x%lx: expected (bl) != found (%08lx)\n", ip, ppc_inst_as_ulong(old)); + return -EINVAL; + } + ret = patch_instruction((u32 *)ip, new); + } else { + return -EINVAL; + } + + return ret; +} + int ftrace_update_ftrace_func(ftrace_func_t func) { unsigned long ip = (unsigned long)(&ftrace_call);
Currently, we validate instructions around the ftrace location every time we have to enable/disable ftrace. Introduce ftrace_init_nop() to instead perform all the validation during ftrace initialization. This allows us to simply patch the necessary instructions during enabling/disabling ftrace. Signed-off-by: Naveen N Rao <naveen@kernel.org> --- arch/powerpc/include/asm/ftrace.h | 6 +++ arch/powerpc/kernel/trace/ftrace.c | 71 ++++++++++++++++++++++++++++++ 2 files changed, 77 insertions(+)