diff options
Diffstat (limited to 'arch/riscv/kernel/ftrace.c')
-rw-r--r-- | arch/riscv/kernel/ftrace.c | 175 |
1 files changed, 173 insertions, 2 deletions
diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c index d0de68d..1157b6b 100644 --- a/arch/riscv/kernel/ftrace.c +++ b/arch/riscv/kernel/ftrace.c @@ -6,9 +6,126 @@ */ #include <linux/ftrace.h> +#include <linux/uaccess.h> +#include <asm/cacheflush.h> +#ifdef CONFIG_DYNAMIC_FTRACE +static int ftrace_check_current_call(unsigned long hook_pos, + unsigned int *expected) +{ + unsigned int replaced[2]; + unsigned int nops[2] = {NOP4, NOP4}; + + /* we expect nops at the hook position */ + if (!expected) + expected = nops; + + /* + * Read the text we want to modify; + * return must be -EFAULT on read error + */ + if (probe_kernel_read(replaced, (void *)hook_pos, MCOUNT_INSN_SIZE)) + return -EFAULT; + + /* + * Make sure it is what we expect it to be; + * return must be -EINVAL on failed comparison + */ + if (memcmp(expected, replaced, sizeof(replaced))) { + pr_err("%p: expected (%08x %08x) but get (%08x %08x)", + (void *)hook_pos, expected[0], expected[1], replaced[0], + replaced[1]); + return -EINVAL; + } + + return 0; +} + +static int __ftrace_modify_call(unsigned long hook_pos, unsigned long target, + bool enable) +{ + unsigned int call[2]; + unsigned int nops[2] = {NOP4, NOP4}; + int ret = 0; + + make_call(hook_pos, target, call); + + /* replace the auipc-jalr pair at once */ + ret = probe_kernel_write((void *)hook_pos, enable ? call : nops, + MCOUNT_INSN_SIZE); + /* return must be -EPERM on write error */ + if (ret) + return -EPERM; + + smp_mb(); + flush_icache_range((void *)hook_pos, (void *)hook_pos + MCOUNT_INSN_SIZE); + + return 0; +} + +int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) +{ + int ret = ftrace_check_current_call(rec->ip, NULL); + + if (ret) + return ret; + + return __ftrace_modify_call(rec->ip, addr, true); +} + +int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, + unsigned long addr) +{ + unsigned int call[2]; + int ret; + + make_call(rec->ip, addr, call); + ret = ftrace_check_current_call(rec->ip, call); + + if (ret) + return ret; + + return __ftrace_modify_call(rec->ip, addr, false); +} + +int ftrace_update_ftrace_func(ftrace_func_t func) +{ + int ret = __ftrace_modify_call((unsigned long)&ftrace_call, + (unsigned long)func, true); + if (!ret) { + ret = __ftrace_modify_call((unsigned long)&ftrace_regs_call, + (unsigned long)func, true); + } + + return ret; +} + +int __init ftrace_dyn_arch_init(void) +{ + return 0; +} +#endif + +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, + unsigned long addr) +{ + unsigned int call[2]; + int ret; + + make_call(rec->ip, old_addr, call); + ret = ftrace_check_current_call(rec->ip, call); + + if (ret) + return ret; + + return __ftrace_modify_call(rec->ip, addr, true); +} +#endif + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER /* - * Most of this file is copied from arm64. + * Most of this function is copied from arm64. */ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, unsigned long frame_pointer) @@ -34,8 +151,62 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, return; err = ftrace_push_return_trace(old, self_addr, &trace.depth, - frame_pointer, NULL); + frame_pointer, parent); if (err == -EBUSY) return; *parent = return_hooker; } + +#ifdef CONFIG_DYNAMIC_FTRACE +extern void ftrace_graph_call(void); +int ftrace_enable_ftrace_graph_caller(void) +{ + unsigned int call[2]; + static int init_graph = 1; + int ret; + + make_call(&ftrace_graph_call, &ftrace_stub, call); + + /* + * When enabling graph tracer for the first time, ftrace_graph_call + * should contains a call to ftrace_stub. Once it has been disabled, + * the 8-bytes at the position becomes NOPs. + */ + if (init_graph) { + ret = ftrace_check_current_call((unsigned long)&ftrace_graph_call, + call); + init_graph = 0; + } else { + ret = ftrace_check_current_call((unsigned long)&ftrace_graph_call, + NULL); + } + + if (ret) + return ret; + + return __ftrace_modify_call((unsigned long)&ftrace_graph_call, + (unsigned long)&prepare_ftrace_return, true); +} + +int ftrace_disable_ftrace_graph_caller(void) +{ + unsigned int call[2]; + int ret; + + make_call(&ftrace_graph_call, &prepare_ftrace_return, call); + + /* + * This is to make sure that ftrace_enable_ftrace_graph_caller + * did the right thing. + */ + ret = ftrace_check_current_call((unsigned long)&ftrace_graph_call, + call); + + if (ret) + return ret; + + return __ftrace_modify_call((unsigned long)&ftrace_graph_call, + (unsigned long)&prepare_ftrace_return, false); +} +#endif /* CONFIG_DYNAMIC_FTRACE */ +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |