Move ftrace over to using the generic x86 text_poke functions; this
avoids having a second/different copy of that code around.
Cc: Daniel Bristot de Oliveira <bris...@redhat.com>
Cc: Steven Rostedt <rost...@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
---
arch/x86/include/asm/ftrace.h | 2
arch/x86/kernel/ftrace.c | 571 +++---------------------------------------
arch/x86/kernel/traps.c | 9
3 files changed, 51 insertions(+), 531 deletions(-)
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -35,8 +35,6 @@ struct dyn_arch_ftrace {
/* No extra data needed for x86 */
};
-int ftrace_int3_handler(struct pt_regs *regs);
-
#define FTRACE_GRAPH_TRAMP_ADDR FTRACE_GRAPH_ADDR
#endif /* CONFIG_DYNAMIC_FTRACE */
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -43,16 +43,17 @@ int ftrace_arch_code_modify_prepare(void
* ftrace has it set to "read/write".
*/
mutex_lock(&text_mutex);
- set_kernel_text_rw();
- set_all_modules_text_rw();
+ WARN_ON_ONCE(tp_vec_nr);
return 0;
}
int ftrace_arch_code_modify_post_process(void)
__releases(&text_mutex)
{
- set_all_modules_text_ro();
- set_kernel_text_ro();
+ if (tp_vec_nr) {
+ text_poke_bp_batch(tp_vec, tp_vec_nr);
+ tp_vec_nr = 0;
+ }
mutex_unlock(&text_mutex);
return 0;
}
@@ -60,67 +61,36 @@ int ftrace_arch_code_modify_post_process
union ftrace_code_union {
char code[MCOUNT_INSN_SIZE];
struct {
- unsigned char op;
+ char op;
int offset;
} __attribute__((packed));
};
-static int ftrace_calc_offset(long ip, long addr)
-{
- return (int)(addr - ip);
-}
-
-static unsigned char *
-ftrace_text_replace(unsigned char op, unsigned long ip, unsigned long addr)
+static char *ftrace_text_replace(char op, unsigned long ip, unsigned long addr)
{
static union ftrace_code_union calc;
- calc.op = op;
- calc.offset = ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr);
+ calc.op = op;
+ calc.offset = (int)(addr - (ip + MCOUNT_INSN_SIZE));
return calc.code;
}
-static unsigned char *
-ftrace_call_replace(unsigned long ip, unsigned long addr)
-{
- return ftrace_text_replace(0xe8, ip, addr);
-}
-
-static inline int
-within(unsigned long addr, unsigned long start, unsigned long end)
+static char *ftrace_nop_replace(void)
{
- return addr >= start && addr < end;
-}
-
-static unsigned long text_ip_addr(unsigned long ip)
-{
- /*
- * On x86_64, kernel text mappings are mapped read-only, so we use
- * the kernel identity mapping instead of the kernel text mapping
- * to modify the kernel text.
- *
- * For 32bit kernels, these mappings are same and we can use
- * kernel identity mapping to modify code.
- */
- if (within(ip, (unsigned long)_text, (unsigned long)_etext))
- ip = (unsigned long)__va(__pa_symbol(ip));
-
- return ip;
+ return ideal_nops[NOP_ATOMIC5];
}
-static const unsigned char *ftrace_nop_replace(void)
+static char *ftrace_call_replace(unsigned long ip, unsigned long addr)
{
- return ideal_nops[NOP_ATOMIC5];
+ return ftrace_text_replace(CALL_INSN_OPCODE, ip, addr);
}
-static int
-ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code,
- unsigned const char *new_code)
+static int;
+ftrace_modify_code_direct(unsigned long ip, const char *old_code,
+ const char *new_code)
{
- unsigned char replaced[MCOUNT_INSN_SIZE];
-
- ftrace_expected = old_code;
+ char cur_code[MCOUNT_INSN_SIZE];
/*
* Note:
@@ -129,31 +99,23 @@ ftrace_modify_code_direct(unsigned long
* Carefully read and modify the code with probe_kernel_*(), and make
* sure what we read is what we expected it to be before modifying it.
*/
-
/* read the text we want to modify */
- if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
+ if (probe_kernel_read(cur_code, (void *)ip, MCOUNT_INSN_SIZE))
return -EFAULT;
/* Make sure it is what we expect it to be */
- if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
+ if (memcmp(cur_code, old_code, MCOUNT_INSN_SIZE) != 0)
return -EINVAL;
- ip = text_ip_addr(ip);
-
/* replace the text with the new text */
- if (probe_kernel_write((void *)ip, new_code, MCOUNT_INSN_SIZE))
- return -EPERM;
-
- sync_core();
-
+ text_poke_early((void *)ip, new_code, MCOUNT_INSN_SIZE);
return 0;
}
-int ftrace_make_nop(struct module *mod,
- struct dyn_ftrace *rec, unsigned long addr)
+int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long
addr)
{
- unsigned const char *new, *old;
unsigned long ip = rec->ip;
+ const char *new, *old;
old = ftrace_call_replace(ip, addr);
new = ftrace_nop_replace();
@@ -166,20 +128,21 @@ int ftrace_make_nop(struct module *mod,
* We do not want to use the breakpoint version in this case,
* just modify the code directly.
*/
- if (addr == MCOUNT_ADDR)
- return ftrace_modify_code_direct(rec->ip, old, new);
+ if (addr == MCOUNT)
+ return ftrace_modify_code_direct(ip, old, new);
- ftrace_expected = NULL;
-
- /* Normal cases use add_brk_on_nop */
+ /*
+ * x86 overrides ftrace_replace_code -- this function will never be used
+ * in this case.
+ */
WARN_ONCE(1, "invalid use of ftrace_make_nop");
return -EINVAL;
}
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
- unsigned const char *new, *old;
unsigned long ip = rec->ip;
+ const char *new, *old;
old = ftrace_nop_replace();
new = ftrace_call_replace(ip, addr);
@@ -189,43 +152,6 @@ int ftrace_make_call(struct dyn_ftrace *
}
/*
- * The modifying_ftrace_code is used to tell the breakpoint
- * handler to call ftrace_int3_handler(). If it fails to
- * call this handler for a breakpoint added by ftrace, then
- * the kernel may crash.
- *
- * As atomic_writes on x86 do not need a barrier, we do not
- * need to add smp_mb()s for this to work. It is also considered
- * that we can not read the modifying_ftrace_code before
- * executing the breakpoint. That would be quite remarkable if
- * it could do that. Here's the flow that is required:
- *
- * CPU-0 CPU-1
- *
- * atomic_inc(mfc);
- * write int3s
- * <trap-int3> // implicit (r)mb
- * if (atomic_read(mfc))
- * call ftrace_int3_handler()
- *
- * Then when we are finished:
- *
- * atomic_dec(mfc);
- *
- * If we hit a breakpoint that was not set by ftrace, it does not
- * matter if ftrace_int3_handler() is called or not. It will
- * simply be ignored. But it is crucial that a ftrace nop/caller
- * breakpoint is handled. No other user should ever place a
- * breakpoint on an ftrace nop/caller location. It must only
- * be done by this code.
- */
-atomic_t modifying_ftrace_code __read_mostly;
-
-static int
-ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
- unsigned const char *new_code);
-
-/*
* Should never be called:
* As it is only called by __ftrace_replace_code() which is called by
* ftrace_replace_code() that x86 overrides, and by ftrace_update_code()
@@ -237,452 +163,57 @@ int ftrace_modify_call(struct dyn_ftrace
unsigned long addr)
{
WARN_ON(1);
- ftrace_expected = NULL;
return -EINVAL;
}
-static unsigned long ftrace_update_func;
-static unsigned long ftrace_update_func_call;
-
-static int update_ftrace_func(unsigned long ip, void *new)
-{
- unsigned char old[MCOUNT_INSN_SIZE];
- int ret;
-
- memcpy(old, (void *)ip, MCOUNT_INSN_SIZE);
-
- ftrace_update_func = ip;
- /* Make sure the breakpoints see the ftrace_update_func update */
- smp_wmb();
-
- /* See comment above by declaration of modifying_ftrace_code */
- atomic_inc(&modifying_ftrace_code);
-
- ret = ftrace_modify_code(ip, old, new);
-
- atomic_dec(&modifying_ftrace_code);
-
- return ret;
-}
-
int ftrace_update_ftrace_func(ftrace_func_t func)
{
unsigned long ip = (unsigned long)(&ftrace_call);
unsigned char *new;
- int ret;
-
- ftrace_update_func_call = (unsigned long)func;
new = ftrace_call_replace(ip, (unsigned long)func);
- ret = update_ftrace_func(ip, new);
-
- /* Also update the regs callback function */
- if (!ret) {
- ip = (unsigned long)(&ftrace_regs_call);
- new = ftrace_call_replace(ip, (unsigned long)func);
- ret = update_ftrace_func(ip, new);
- }
-
- return ret;
-}
-
-static nokprobe_inline int is_ftrace_caller(unsigned long ip)
-{
- if (ip == ftrace_update_func)
- return 1;
-
- return 0;
-}
-
-/*
- * A breakpoint was added to the code address we are about to
- * modify, and this is the handle that will just skip over it.
- * We are either changing a nop into a trace call, or a trace
- * call to a nop. While the change is taking place, we treat
- * it just like it was a nop.
- */
-int ftrace_int3_handler(struct pt_regs *regs)
-{
- unsigned long ip;
-
- if (WARN_ON_ONCE(!regs))
- return 0;
-
- ip = regs->ip - INT3_INSN_SIZE;
-
- if (ftrace_location(ip)) {
- int3_emulate_call(regs, (unsigned long)ftrace_regs_caller);
- return 1;
- } else if (is_ftrace_caller(ip)) {
- if (!ftrace_update_func_call) {
- int3_emulate_jmp(regs, ip + CALL_INSN_SIZE);
- return 1;
- }
- int3_emulate_call(regs, ftrace_update_func_call);
- return 1;
- }
-
- return 0;
-}
-NOKPROBE_SYMBOL(ftrace_int3_handler);
-
-static int ftrace_write(unsigned long ip, const char *val, int size)
-{
- ip = text_ip_addr(ip);
-
- if (probe_kernel_write((void *)ip, val, size))
- return -EPERM;
-
- return 0;
-}
-
-static int add_break(unsigned long ip, const char *old)
-{
- unsigned char replaced[MCOUNT_INSN_SIZE];
- unsigned char brk = BREAKPOINT_INSTRUCTION;
-
- if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
- return -EFAULT;
-
- ftrace_expected = old;
-
- /* Make sure it is what we expect it to be */
- if (memcmp(replaced, old, MCOUNT_INSN_SIZE) != 0)
- return -EINVAL;
-
- return ftrace_write(ip, &brk, 1);
-}
-
-static int add_brk_on_call(struct dyn_ftrace *rec, unsigned long addr)
-{
- unsigned const char *old;
- unsigned long ip = rec->ip;
-
- old = ftrace_call_replace(ip, addr);
-
- return add_break(rec->ip, old);
-}
-
-
-static int add_brk_on_nop(struct dyn_ftrace *rec)
-{
- unsigned const char *old;
-
- old = ftrace_nop_replace();
-
- return add_break(rec->ip, old);
-}
-
-static int add_breakpoints(struct dyn_ftrace *rec, bool enable)
-{
- unsigned long ftrace_addr;
- int ret;
-
- ftrace_addr = ftrace_get_addr_curr(rec);
-
- ret = ftrace_test_record(rec, enable);
-
- switch (ret) {
- case FTRACE_UPDATE_IGNORE:
- return 0;
-
- case FTRACE_UPDATE_MAKE_CALL:
- /* converting nop to call */
- return add_brk_on_nop(rec);
-
- case FTRACE_UPDATE_MODIFY_CALL:
- case FTRACE_UPDATE_MAKE_NOP:
- /* converting a call to a nop */
- return add_brk_on_call(rec, ftrace_addr);
- }
- return 0;
-}
-
-/*
- * On error, we need to remove breakpoints. This needs to
- * be done caefully. If the address does not currently have a
- * breakpoint, we know we are done. Otherwise, we look at the
- * remaining 4 bytes of the instruction. If it matches a nop
- * we replace the breakpoint with the nop. Otherwise we replace
- * it with the call instruction.
- */
-static int remove_breakpoint(struct dyn_ftrace *rec)
-{
- unsigned char ins[MCOUNT_INSN_SIZE];
- unsigned char brk = BREAKPOINT_INSTRUCTION;
- const unsigned char *nop;
- unsigned long ftrace_addr;
- unsigned long ip = rec->ip;
-
- /* If we fail the read, just give up */
- if (probe_kernel_read(ins, (void *)ip, MCOUNT_INSN_SIZE))
- return -EFAULT;
-
- /* If this does not have a breakpoint, we are done */
- if (ins[0] != brk)
- return 0;
-
- nop = ftrace_nop_replace();
-
- /*
- * If the last 4 bytes of the instruction do not match
- * a nop, then we assume that this is a call to ftrace_addr.
- */
- if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0) {
- /*
- * For extra paranoidism, we check if the breakpoint is on
- * a call that would actually jump to the ftrace_addr.
- * If not, don't touch the breakpoint, we make just create
- * a disaster.
- */
- ftrace_addr = ftrace_get_addr_new(rec);
- nop = ftrace_call_replace(ip, ftrace_addr);
-
- if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) == 0)
- goto update;
-
- /* Check both ftrace_addr and ftrace_old_addr */
- ftrace_addr = ftrace_get_addr_curr(rec);
- nop = ftrace_call_replace(ip, ftrace_addr);
-
- ftrace_expected = nop;
-
- if (memcmp(&ins[1], &nop[1], MCOUNT_INSN_SIZE - 1) != 0)
- return -EINVAL;
- }
-
- update:
- return ftrace_write(ip, nop, 1);
-}
-
-static int add_update_code(unsigned long ip, unsigned const char *new)
-{
- /* skip breakpoint */
- ip++;
- new++;
- return ftrace_write(ip, new, MCOUNT_INSN_SIZE - 1);
-}
-
-static int add_update_call(struct dyn_ftrace *rec, unsigned long addr)
-{
- unsigned long ip = rec->ip;
- unsigned const char *new;
-
- new = ftrace_call_replace(ip, addr);
- return add_update_code(ip, new);
-}
-
-static int add_update_nop(struct dyn_ftrace *rec)
-{
- unsigned long ip = rec->ip;
- unsigned const char *new;
-
- new = ftrace_nop_replace();
- return add_update_code(ip, new);
-}
-
-static int add_update(struct dyn_ftrace *rec, bool enable)
-{
- unsigned long ftrace_addr;
- int ret;
-
- ret = ftrace_test_record(rec, enable);
-
- ftrace_addr = ftrace_get_addr_new(rec);
-
- switch (ret) {
- case FTRACE_UPDATE_IGNORE:
- return 0;
-
- case FTRACE_UPDATE_MODIFY_CALL:
- case FTRACE_UPDATE_MAKE_CALL:
- /* converting nop to call */
- return add_update_call(rec, ftrace_addr);
-
- case FTRACE_UPDATE_MAKE_NOP:
- /* converting a call to a nop */
- return add_update_nop(rec);
- }
-
- return 0;
-}
-
-static int finish_update_call(struct dyn_ftrace *rec, unsigned long addr)
-{
- unsigned long ip = rec->ip;
- unsigned const char *new;
-
- new = ftrace_call_replace(ip, addr);
-
- return ftrace_write(ip, new, 1);
-}
-
-static int finish_update_nop(struct dyn_ftrace *rec)
-{
- unsigned long ip = rec->ip;
- unsigned const char *new;
-
- new = ftrace_nop_replace();
-
- return ftrace_write(ip, new, 1);
-}
-
-static int finish_update(struct dyn_ftrace *rec, bool enable)
-{
- unsigned long ftrace_addr;
- int ret;
-
- ret = ftrace_update_record(rec, enable);
-
- ftrace_addr = ftrace_get_addr_new(rec);
-
- switch (ret) {
- case FTRACE_UPDATE_IGNORE:
- return 0;
-
- case FTRACE_UPDATE_MODIFY_CALL:
- case FTRACE_UPDATE_MAKE_CALL:
- /* converting nop to call */
- return finish_update_call(rec, ftrace_addr);
-
- case FTRACE_UPDATE_MAKE_NOP:
- /* converting a call to a nop */
- return finish_update_nop(rec);
- }
+ text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL);
return 0;
}
-static void do_sync_core(void *data)
-{
- sync_core();
-}
-
-static void run_sync(void)
-{
- int enable_irqs;
-
- /* No need to sync if there's only one CPU */
- if (num_online_cpus() == 1)
- return;
-
- enable_irqs = irqs_disabled();
-
- /* We may be called with interrupts disabled (on bootup). */
- if (enable_irqs)
- local_irq_enable();
- on_each_cpu(do_sync_core, NULL, 1);
- if (enable_irqs)
- local_irq_disable();
-}
-
void ftrace_replace_code(int enable)
{
struct ftrace_rec_iter *iter;
+ struct text_poke_loc *tp;
struct dyn_ftrace *rec;
- const char *report = "adding breakpoints";
- int count = 0;
- int ret;
+ const char *new;
for_ftrace_rec_iter(iter) {
rec = ftrace_rec_iter_record(iter);
- ret = add_breakpoints(rec, enable);
- if (ret)
- goto remove_breakpoints;
- count++;
- }
-
- run_sync();
-
- report = "updating code";
- count = 0;
-
- for_ftrace_rec_iter(iter) {
- rec = ftrace_rec_iter_record(iter);
-
- ret = add_update(rec, enable);
- if (ret)
- goto remove_breakpoints;
- count++;
- }
-
- run_sync();
-
- report = "removing breakpoints";
- count = 0;
-
- for_ftrace_rec_iter(iter) {
- rec = ftrace_rec_iter_record(iter);
-
- ret = finish_update(rec, enable);
- if (ret)
- goto remove_breakpoints;
- count++;
- }
-
- run_sync();
+ if (tp_vec_nr == TP_VEC_MAX) {
+ text_poke_bp_batch(tp_vec, tp_vec_nr);
+ tp_vec_nr = 0;
+ }
- return;
+ switch (ftrace_test_record(rec, enable)) {
+ case FTRACE_UPDATE_IGNORE:
+ continue;
+
+ case FTRACE_UPDATE_MODIFY_CALL:
+ case FTRACE_UPDATE_MAKE_CALL:
+ new = ftrace_call_replace(rec->ip,
ftrace_get_addr_new(rec));
+ break;
+
+ case FTRACE_UPDATE_MAKE_NOP:
+ new = ftrace_nop_replace();
+ break;
+ };
- remove_breakpoints:
- pr_warn("Failed on %s (%d):\n", report, count);
- ftrace_bug(ret, rec);
- for_ftrace_rec_iter(iter) {
- rec = ftrace_rec_iter_record(iter);
- /*
- * Breakpoints are handled only when this function is in
- * progress. The system could not work with them.
- */
- if (remove_breakpoint(rec))
- BUG();
+ tp = &tp_vec[tp_vec_nr++];
+ text_poke_loc_init(tp, (void *)rec->ip, new, MCOUNT_INSN_SIZE,
NULL);
}
- run_sync();
-}
-
-static int
-ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
- unsigned const char *new_code)
-{
- int ret;
-
- ret = add_break(ip, old_code);
- if (ret)
- goto out;
-
- run_sync();
-
- ret = add_update_code(ip, new_code);
- if (ret)
- goto fail_update;
-
- run_sync();
-
- ret = ftrace_write(ip, new_code, 1);
- /*
- * The breakpoint is handled only when this function is in progress.
- * The system could not work if we could not remove it.
- */
- BUG_ON(ret);
- out:
- run_sync();
- return ret;
-
- fail_update:
- /* Also here the system could not work with the breakpoint */
- if (ftrace_write(ip, old_code, 1))
- BUG();
- goto out;
}
void arch_ftrace_update_code(int command)
{
- /* See comment above by declaration of modifying_ftrace_code */
- atomic_inc(&modifying_ftrace_code);
-
ftrace_modify_all_code(command);
-
- atomic_dec(&modifying_ftrace_code);
}
int __init ftrace_dyn_arch_init(void)
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -568,15 +568,6 @@ NOKPROBE_SYMBOL(do_general_protection);
dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
{
-#ifdef CONFIG_DYNAMIC_FTRACE
- /*
- * ftrace must be first, everything else may cause a recursive crash.
- * See note by declaration of modifying_ftrace_code in ftrace.c
- */
- if (unlikely(atomic_read(&modifying_ftrace_code)) &&
- ftrace_int3_handler(regs))
- return;
-#endif
if (poke_int3_handler(regs))
return;
