diff options
| -rw-r--r-- | arch/powerpc/include/asm/ftrace.h | 6 | ||||
| -rw-r--r-- | arch/powerpc/kernel/trace/ftrace.c | 71 |
2 files changed, 77 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h index 702aaf2efa96..ef9f0b97670d 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 278bf8e52b6e..98bd099c428e 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); |