diff options
Diffstat (limited to 'arch/arm/kernel/ftrace.c')
-rw-r--r-- | arch/arm/kernel/ftrace.c | 139 |
1 files changed, 101 insertions, 38 deletions
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c index bda949fd84e8..a0b6d1e3812f 100644 --- a/arch/arm/kernel/ftrace.c +++ b/arch/arm/kernel/ftrace.c @@ -22,11 +22,24 @@ #include <asm/ftrace.h> #include <asm/insn.h> #include <asm/set_memory.h> +#include <asm/stacktrace.h> +#include <asm/patch.h> +/* + * The compiler emitted profiling hook consists of + * + * PUSH {LR} + * BL __gnu_mcount_nc + * + * To turn this combined sequence into a NOP, we need to restore the value of + * SP before the PUSH. Let's use an ADD rather than a POP into LR, as LR is not + * modified anyway, and reloading LR from memory is highly likely to be less + * efficient. + */ #ifdef CONFIG_THUMB2_KERNEL -#define NOP 0xf85deb04 /* pop.w {lr} */ +#define NOP 0xf10d0d04 /* add.w sp, sp, #4 */ #else -#define NOP 0xe8bd4000 /* pop {lr} */ +#define NOP 0xe28dd004 /* add sp, sp, #4 */ #endif #ifdef CONFIG_DYNAMIC_FTRACE @@ -35,9 +48,7 @@ static int __ftrace_modify_code(void *data) { int *command = data; - set_kernel_text_rw(); ftrace_modify_all_code(*command); - set_kernel_text_ro(); return 0; } @@ -52,28 +63,36 @@ static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec) return NOP; } -static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr) +void ftrace_caller_from_init(void); +void ftrace_regs_caller_from_init(void); + +static unsigned long __ref adjust_address(struct dyn_ftrace *rec, + unsigned long addr) { - return addr; + if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE) || + system_state >= SYSTEM_FREEING_INITMEM || + likely(!is_kernel_inittext(rec->ip))) + return addr; + if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) || + addr == (unsigned long)&ftrace_caller) + return (unsigned long)&ftrace_caller_from_init; + return (unsigned long)&ftrace_regs_caller_from_init; } -int ftrace_arch_code_modify_prepare(void) +void ftrace_arch_code_modify_prepare(void) { - set_all_modules_text_rw(); - return 0; } -int ftrace_arch_code_modify_post_process(void) +void ftrace_arch_code_modify_post_process(void) { - set_all_modules_text_ro(); /* Make sure any TLB misses during machine stop are cleared. */ flush_tlb_all(); - return 0; } -static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr) +static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr, + bool warn) { - return arm_gen_branch_link(pc, addr); + return arm_gen_branch_link(pc, addr, warn); } static int ftrace_modify_code(unsigned long pc, unsigned long old, @@ -81,26 +100,21 @@ static int ftrace_modify_code(unsigned long pc, unsigned long old, { unsigned long replaced; - if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) { + if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) old = __opcode_to_mem_thumb32(old); - new = __opcode_to_mem_thumb32(new); - } else { + else old = __opcode_to_mem_arm(old); - new = __opcode_to_mem_arm(new); - } if (validate) { - if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE)) + if (copy_from_kernel_nofault(&replaced, (void *)pc, + MCOUNT_INSN_SIZE)) return -EFAULT; if (replaced != old) return -EINVAL; } - if (probe_kernel_write((void *)pc, &new, MCOUNT_INSN_SIZE)) - return -EPERM; - - flush_icache_range(pc, pc + MCOUNT_INSN_SIZE); + __patch_text((void *)pc, new); return 0; } @@ -112,14 +126,14 @@ int ftrace_update_ftrace_func(ftrace_func_t func) int ret; pc = (unsigned long)&ftrace_call; - new = ftrace_call_replace(pc, (unsigned long)func); + new = ftrace_call_replace(pc, (unsigned long)func, true); ret = ftrace_modify_code(pc, 0, new, false); #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS if (!ret) { pc = (unsigned long)&ftrace_regs_call; - new = ftrace_call_replace(pc, (unsigned long)func); + new = ftrace_call_replace(pc, (unsigned long)func, true); ret = ftrace_modify_code(pc, 0, new, false); } @@ -132,10 +146,22 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) { unsigned long new, old; unsigned long ip = rec->ip; + unsigned long aaddr = adjust_address(rec, addr); + struct module *mod = NULL; + +#ifdef CONFIG_ARM_MODULE_PLTS + mod = rec->arch.mod; +#endif old = ftrace_nop_replace(rec); - new = ftrace_call_replace(ip, adjust_address(rec, addr)); + new = ftrace_call_replace(ip, aaddr, !mod); +#ifdef CONFIG_ARM_MODULE_PLTS + if (!new && mod) { + aaddr = get_module_plt(mod, ip, aaddr); + new = ftrace_call_replace(ip, aaddr, true); + } +#endif return ftrace_modify_code(rec->ip, old, new, true); } @@ -148,9 +174,9 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long new, old; unsigned long ip = rec->ip; - old = ftrace_call_replace(ip, adjust_address(rec, old_addr)); + old = ftrace_call_replace(ip, adjust_address(rec, old_addr), true); - new = ftrace_call_replace(ip, adjust_address(rec, addr)); + new = ftrace_call_replace(ip, adjust_address(rec, addr), true); return ftrace_modify_code(rec->ip, old, new, true); } @@ -160,27 +186,47 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) { + unsigned long aaddr = adjust_address(rec, addr); unsigned long ip = rec->ip; unsigned long old; unsigned long new; int ret; - old = ftrace_call_replace(ip, adjust_address(rec, addr)); +#ifdef CONFIG_ARM_MODULE_PLTS + /* mod is only supplied during module loading */ + if (!mod) + mod = rec->arch.mod; + else + rec->arch.mod = mod; +#endif + + old = ftrace_call_replace(ip, aaddr, + !IS_ENABLED(CONFIG_ARM_MODULE_PLTS) || !mod); +#ifdef CONFIG_ARM_MODULE_PLTS + if (!old && mod) { + aaddr = get_module_plt(mod, ip, aaddr); + old = ftrace_call_replace(ip, aaddr, true); + } +#endif + new = ftrace_nop_replace(rec); - ret = ftrace_modify_code(ip, old, new, true); + /* + * Locations in .init.text may call __gnu_mcount_mc via a linker + * emitted veneer if they are too far away from its implementation, and + * so validation may fail spuriously in such cases. Let's work around + * this by omitting those from validation. + */ + ret = ftrace_modify_code(ip, old, new, !is_kernel_inittext(ip)); return ret; } - -int __init ftrace_dyn_arch_init(void) -{ - return 0; -} #endif /* CONFIG_DYNAMIC_FTRACE */ #ifdef CONFIG_FUNCTION_GRAPH_TRACER +asmlinkage void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, - unsigned long frame_pointer) + unsigned long frame_pointer, + unsigned long stack_pointer) { unsigned long return_hooker = (unsigned long) &return_to_handler; unsigned long old; @@ -188,6 +234,23 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, if (unlikely(atomic_read(¤t->tracing_graph_pause))) return; + if (IS_ENABLED(CONFIG_UNWINDER_FRAME_POINTER)) { + /* FP points one word below parent's top of stack */ + frame_pointer += 4; + } else { + struct stackframe frame = { + .fp = frame_pointer, + .sp = stack_pointer, + .lr = self_addr, + .pc = self_addr, + }; + if (unwind_frame(&frame) < 0) + return; + if (frame.lr != self_addr) + parent = frame.lr_addr; + frame_pointer = frame.sp; + } + old = *parent; *parent = return_hooker; @@ -208,7 +271,7 @@ static int __ftrace_modify_caller(unsigned long *callsite, unsigned long caller_fn = (unsigned long) func; unsigned long pc = (unsigned long) callsite; unsigned long branch = arm_gen_branch(pc, caller_fn); - unsigned long nop = 0xe1a00000; /* mov r0, r0 */ + unsigned long nop = arm_gen_nop(); unsigned long old = enable ? nop : branch; unsigned long new = enable ? branch : nop; |