diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/loongarch/kernel/ftrace_dyn.c | 116 |
1 files changed, 57 insertions, 59 deletions
diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c index c5f4b4681ddc..eb624af93617 100644 --- a/arch/loongarch/kernel/ftrace_dyn.c +++ b/arch/loongarch/kernel/ftrace_dyn.c @@ -31,16 +31,11 @@ static int ftrace_modify_code(unsigned long pc, u32 old, u32 new, bool validate) } #ifdef CONFIG_MODULES -static inline int __get_mod(struct module **mod, unsigned long addr) +static bool reachable_by_bl(unsigned long addr, unsigned long pc) { - preempt_disable(); - *mod = __module_text_address(addr); - preempt_enable(); + long offset = (long)addr - (long)pc; - if (WARN_ON(!(*mod))) - return -EINVAL; - - return 0; + return offset >= -SZ_128M && offset < SZ_128M; } static struct plt_entry *get_ftrace_plt(struct module *mod, unsigned long addr) @@ -56,17 +51,58 @@ static struct plt_entry *get_ftrace_plt(struct module *mod, unsigned long addr) return NULL; } -static unsigned long get_plt_addr(struct module *mod, unsigned long addr) +/* + * Find the address the callsite must branch to in order to reach '*addr'. + * + * Due to the limited range of 'bl' instruction, modules may be placed too far + * away to branch directly and we must use a PLT. + * + * Returns true when '*addr' contains a reachable target address, or has been + * modified to contain a PLT address. Returns false otherwise. + */ +static bool ftrace_find_callable_addr(struct dyn_ftrace *rec, struct module *mod, unsigned long *addr) { + unsigned long pc = rec->ip + LOONGARCH_INSN_SIZE; struct plt_entry *plt; - plt = get_ftrace_plt(mod, addr); + /* + * When the target is within range of the 'bl' instruction, use 'addr' + * as-is and branch to that directly. + */ + if (reachable_by_bl(*addr, pc)) + return true; + + /* + * 'mod' is only set at module load time, but if we end up + * dealing with an out-of-range condition, we can assume it + * is due to a module being loaded far away from the kernel. + * + * NOTE: __module_text_address() must be called with preemption + * disabled, but we can rely on ftrace_lock to ensure that 'mod' + * retains its validity throughout the remainder of this code. + */ + if (!mod) { + preempt_disable(); + mod = __module_text_address(pc); + preempt_enable(); + } + + if (WARN_ON(!mod)) + return false; + + plt = get_ftrace_plt(mod, *addr); if (!plt) { - pr_err("ftrace: no module PLT for %ps\n", (void *)addr); - return -EINVAL; + pr_err("ftrace: no module PLT for %ps\n", (void *)*addr); + return false; } - return (unsigned long)plt; + *addr = (unsigned long)plt; + return true; +} +#else /* !CONFIG_MODULES */ +static bool ftrace_find_callable_addr(struct dyn_ftrace *rec, struct module *mod, unsigned long *addr) +{ + return true; } #endif @@ -75,26 +111,14 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned { u32 old, new; unsigned long pc; - long offset __maybe_unused; pc = rec->ip + LOONGARCH_INSN_SIZE; -#ifdef CONFIG_MODULES - offset = (long)pc - (long)addr; - - if (offset < -SZ_128M || offset >= SZ_128M) { - int ret; - struct module *mod; - - ret = __get_mod(&mod, pc); - if (ret) - return ret; - - addr = get_plt_addr(mod, addr); + if (!ftrace_find_callable_addr(rec, NULL, &addr)) + return -EINVAL; - old_addr = get_plt_addr(mod, old_addr); - } -#endif + if (!ftrace_find_callable_addr(rec, NULL, &old_addr)) + return -EINVAL; new = larch_insn_gen_bl(pc, addr); old = larch_insn_gen_bl(pc, old_addr); @@ -151,24 +175,11 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) { u32 old, new; unsigned long pc; - long offset __maybe_unused; pc = rec->ip + LOONGARCH_INSN_SIZE; -#ifdef CONFIG_MODULES - offset = (long)pc - (long)addr; - - if (offset < -SZ_128M || offset >= SZ_128M) { - int ret; - struct module *mod; - - ret = __get_mod(&mod, pc); - if (ret) - return ret; - - addr = get_plt_addr(mod, addr); - } -#endif + if (!ftrace_find_callable_addr(rec, NULL, &addr)) + return -EINVAL; old = larch_insn_gen_nop(); new = larch_insn_gen_bl(pc, addr); @@ -180,24 +191,11 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long ad { u32 old, new; unsigned long pc; - long offset __maybe_unused; pc = rec->ip + LOONGARCH_INSN_SIZE; -#ifdef CONFIG_MODULES - offset = (long)pc - (long)addr; - - if (offset < -SZ_128M || offset >= SZ_128M) { - int ret; - struct module *mod; - - ret = __get_mod(&mod, pc); - if (ret) - return ret; - - addr = get_plt_addr(mod, addr); - } -#endif + if (!ftrace_find_callable_addr(rec, NULL, &addr)) + return -EINVAL; new = larch_insn_gen_nop(); old = larch_insn_gen_bl(pc, addr); |