123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234 |
- // SPDX-License-Identifier: GPL-2.0
- /*
- * Copyright (C) 2013 Linaro Limited
- * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
- * Copyright (C) 2017 Andes Technology Corporation
- */
- #include <linux/ftrace.h>
- #include <linux/uaccess.h>
- #include <linux/memory.h>
- #include <asm/cacheflush.h>
- #include <asm/patch.h>
- #ifdef CONFIG_DYNAMIC_FTRACE
- int ftrace_arch_code_modify_prepare(void) __acquires(&text_mutex)
- {
- mutex_lock(&text_mutex);
- return 0;
- }
- int ftrace_arch_code_modify_post_process(void) __releases(&text_mutex)
- {
- mutex_unlock(&text_mutex);
- return 0;
- }
- 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 (copy_from_kernel_nofault(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 got (%08x %08x)\n",
- (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};
- make_call(hook_pos, target, call);
- /* Replace the auipc-jalr pair at once. Return -EPERM on write error. */
- if (patch_text_nosync
- ((void *)hook_pos, enable ? call : nops, MCOUNT_INSN_SIZE))
- return -EPERM;
- return 0;
- }
- /*
- * Put 5 instructions with 16 bytes at the front of function within
- * patchable function entry nops' area.
- *
- * 0: REG_S ra, -SZREG(sp)
- * 1: auipc ra, 0x?
- * 2: jalr -?(ra)
- * 3: REG_L ra, -SZREG(sp)
- *
- * So the opcodes is:
- * 0: 0xfe113c23 (sd)/0xfe112e23 (sw)
- * 1: 0x???????? -> auipc
- * 2: 0x???????? -> jalr
- * 3: 0xff813083 (ld)/0xffc12083 (lw)
- */
- #if __riscv_xlen == 64
- #define INSN0 0xfe113c23
- #define INSN3 0xff813083
- #elif __riscv_xlen == 32
- #define INSN0 0xfe112e23
- #define INSN3 0xffc12083
- #endif
- #define FUNC_ENTRY_SIZE 16
- #define FUNC_ENTRY_JMP 4
- int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
- {
- unsigned int call[4] = {INSN0, 0, 0, INSN3};
- unsigned long target = addr;
- unsigned long caller = rec->ip + FUNC_ENTRY_JMP;
- call[1] = to_auipc_insn((unsigned int)(target - caller));
- call[2] = to_jalr_insn((unsigned int)(target - caller));
- if (patch_text_nosync((void *)rec->ip, call, FUNC_ENTRY_SIZE))
- return -EPERM;
- return 0;
- }
- int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
- unsigned long addr)
- {
- unsigned int nops[4] = {NOP4, NOP4, NOP4, NOP4};
- if (patch_text_nosync((void *)rec->ip, nops, FUNC_ENTRY_SIZE))
- return -EPERM;
- return 0;
- }
- /*
- * This is called early on, and isn't wrapped by
- * ftrace_arch_code_modify_{prepare,post_process}() and therefor doesn't hold
- * text_mutex, which triggers a lockdep failure. SMP isn't running so we could
- * just directly poke the text, but it's simpler to just take the lock
- * ourselves.
- */
- int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
- {
- int out;
- ftrace_arch_code_modify_prepare();
- out = ftrace_make_nop(mod, rec, MCOUNT_ADDR);
- ftrace_arch_code_modify_post_process();
- return out;
- }
- 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];
- unsigned long caller = rec->ip + FUNC_ENTRY_JMP;
- int ret;
- make_call(caller, old_addr, call);
- ret = ftrace_check_current_call(caller, call);
- if (ret)
- return ret;
- return __ftrace_modify_call(caller, addr, true);
- }
- #endif
- #ifdef CONFIG_FUNCTION_GRAPH_TRACER
- /*
- * Most of this function is copied from arm64.
- */
- void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
- unsigned long frame_pointer)
- {
- unsigned long return_hooker = (unsigned long)&return_to_handler;
- unsigned long old;
- if (unlikely(atomic_read(¤t->tracing_graph_pause)))
- return;
- /*
- * We don't suffer access faults, so no extra fault-recovery assembly
- * is needed here.
- */
- old = *parent;
- if (!function_graph_enter(old, self_addr, frame_pointer, parent))
- *parent = return_hooker;
- }
- #ifdef CONFIG_DYNAMIC_FTRACE
- extern void ftrace_graph_call(void);
- extern void ftrace_graph_regs_call(void);
- int ftrace_enable_ftrace_graph_caller(void)
- {
- int ret;
- ret = __ftrace_modify_call((unsigned long)&ftrace_graph_call,
- (unsigned long)&prepare_ftrace_return, true);
- if (ret)
- return ret;
- return __ftrace_modify_call((unsigned long)&ftrace_graph_regs_call,
- (unsigned long)&prepare_ftrace_return, true);
- }
- int ftrace_disable_ftrace_graph_caller(void)
- {
- int ret;
- ret = __ftrace_modify_call((unsigned long)&ftrace_graph_call,
- (unsigned long)&prepare_ftrace_return, false);
- if (ret)
- return ret;
- return __ftrace_modify_call((unsigned long)&ftrace_graph_regs_call,
- (unsigned long)&prepare_ftrace_return, false);
- }
- #endif /* CONFIG_DYNAMIC_FTRACE */
- #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
|