diff options
Diffstat (limited to 'arch/arm64/kernel/ftrace.c')
| -rw-r--r-- | arch/arm64/kernel/ftrace.c | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c index 38ebdf063255..5545fe1a9012 100644 --- a/arch/arm64/kernel/ftrace.c +++ b/arch/arm64/kernel/ftrace.c @@ -60,6 +60,89 @@ int ftrace_regs_query_register_offset(const char *name) } #endif +unsigned long ftrace_call_adjust(unsigned long addr) +{ + /* + * When using mcount, addr is the address of the mcount call + * instruction, and no adjustment is necessary. + */ + if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_ARGS)) + return addr; + + /* + * When using patchable-function-entry without pre-function NOPS, addr + * is the address of the first NOP after the function entry point. + * + * The compiler has either generated: + * + * addr+00: func: NOP // To be patched to MOV X9, LR + * addr+04: NOP // To be patched to BL <caller> + * + * Or: + * + * addr-04: BTI C + * addr+00: func: NOP // To be patched to MOV X9, LR + * addr+04: NOP // To be patched to BL <caller> + * + * We must adjust addr to the address of the NOP which will be patched + * to `BL <caller>`, which is at `addr + 4` bytes in either case. + * + */ + if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS)) + return addr + AARCH64_INSN_SIZE; + + /* + * When using patchable-function-entry with pre-function NOPs, addr is + * the address of the first pre-function NOP. + * + * Starting from an 8-byte aligned base, the compiler has either + * generated: + * + * addr+00: NOP // Literal (first 32 bits) + * addr+04: NOP // Literal (last 32 bits) + * addr+08: func: NOP // To be patched to MOV X9, LR + * addr+12: NOP // To be patched to BL <caller> + * + * Or: + * + * addr+00: NOP // Literal (first 32 bits) + * addr+04: NOP // Literal (last 32 bits) + * addr+08: func: BTI C + * addr+12: NOP // To be patched to MOV X9, LR + * addr+16: NOP // To be patched to BL <caller> + * + * We must adjust addr to the address of the NOP which will be patched + * to `BL <caller>`, which is at either addr+12 or addr+16 depending on + * whether there is a BTI. + */ + + if (!IS_ALIGNED(addr, sizeof(unsigned long))) { + WARN_RATELIMIT(1, "Misaligned patch-site %pS\n", + (void *)(addr + 8)); + return 0; + } + + /* Skip the NOPs placed before the function entry point */ + addr += 2 * AARCH64_INSN_SIZE; + + /* Skip any BTI */ + if (IS_ENABLED(CONFIG_ARM64_BTI_KERNEL)) { + u32 insn = le32_to_cpu(*(__le32 *)addr); + + if (aarch64_insn_is_bti(insn)) { + addr += AARCH64_INSN_SIZE; + } else if (insn != aarch64_insn_gen_nop()) { + WARN_RATELIMIT(1, "unexpected insn in patch-site %pS: 0x%08x\n", + (void *)addr, insn); + } + } + + /* Skip the first NOP after function entry */ + addr += AARCH64_INSN_SIZE; + + return addr; +} + /* * Replace a single instruction, which may be a branch or NOP. * If @validate == true, a replaced instruction is checked against 'old'. @@ -98,6 +181,13 @@ int ftrace_update_ftrace_func(ftrace_func_t func) unsigned long pc; u32 new; + /* + * When using CALL_OPS, the function to call is associated with the + * call site, and we don't have a global function pointer to update. + */ + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS)) + return 0; + pc = (unsigned long)ftrace_call; new = aarch64_insn_gen_branch_imm(pc, (unsigned long)func, AARCH64_INSN_BRANCH_LINK); @@ -176,6 +266,44 @@ static bool ftrace_find_callable_addr(struct dyn_ftrace *rec, return true; } +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS +static const struct ftrace_ops *arm64_rec_get_ops(struct dyn_ftrace *rec) +{ + const struct ftrace_ops *ops = NULL; + + if (rec->flags & FTRACE_FL_CALL_OPS_EN) { + ops = ftrace_find_unique_ops(rec); + WARN_ON_ONCE(!ops); + } + + if (!ops) + ops = &ftrace_list_ops; + + return ops; +} + +static int ftrace_rec_set_ops(const struct dyn_ftrace *rec, + const struct ftrace_ops *ops) +{ + unsigned long literal = ALIGN_DOWN(rec->ip - 12, 8); + return aarch64_insn_write_literal_u64((void *)literal, + (unsigned long)ops); +} + +static int ftrace_rec_set_nop_ops(struct dyn_ftrace *rec) +{ + return ftrace_rec_set_ops(rec, &ftrace_nop_ops); +} + +static int ftrace_rec_update_ops(struct dyn_ftrace *rec) +{ + return ftrace_rec_set_ops(rec, arm64_rec_get_ops(rec)); +} +#else +static int ftrace_rec_set_nop_ops(struct dyn_ftrace *rec) { return 0; } +static int ftrace_rec_update_ops(struct dyn_ftrace *rec) { return 0; } +#endif + /* * Turn on the call to ftrace_caller() in instrumented function */ @@ -183,6 +311,11 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) { unsigned long pc = rec->ip; u32 old, new; + int ret; + + ret = ftrace_rec_update_ops(rec); + if (ret) + return ret; if (!ftrace_find_callable_addr(rec, NULL, &addr)) return -EINVAL; @@ -193,6 +326,19 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) return ftrace_modify_code(pc, old, new, true); } +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, + unsigned long addr) +{ + if (WARN_ON_ONCE(old_addr != (unsigned long)ftrace_caller)) + return -EINVAL; + if (WARN_ON_ONCE(addr != (unsigned long)ftrace_caller)) + return -EINVAL; + + return ftrace_rec_update_ops(rec); +} +#endif + #ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS /* * The compiler has inserted two NOPs before the regular function prologue. @@ -220,6 +366,11 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec) { unsigned long pc = rec->ip - AARCH64_INSN_SIZE; u32 old, new; + int ret; + + ret = ftrace_rec_set_nop_ops(rec); + if (ret) + return ret; old = aarch64_insn_gen_nop(); new = aarch64_insn_gen_move_reg(AARCH64_INSN_REG_9, @@ -237,9 +388,14 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, { unsigned long pc = rec->ip; u32 old = 0, new; + int ret; new = aarch64_insn_gen_nop(); + ret = ftrace_rec_set_nop_ops(rec); + if (ret) + return ret; + /* * When using mcount, callsites in modules may have been initalized to * call an arbitrary module PLT (which redirects to the _mcount stub) |