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Subject[tip: core/kprobes] x86/ftrace: Use text_poke()
The following commit has been merged into the core/kprobes branch of tip:

Commit-ID: 9706f7c3531fee00505ebd03bf3aa0af76510877
Gitweb: https://git.kernel.org/tip/9706f7c3531fee00505ebd03bf3aa0af76510877
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Mon, 26 Aug 2019 14:48:23 +02:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Fri, 15 Nov 2019 09:07:42 +01:00

x86/ftrace: Use text_poke()

Move ftrace over to using the generic x86 text_poke functions; this
avoids having a second/different copy of that code around.

This also avoids ftrace violating the (new) W^X rule and avoids
fragmenting the kernel text page-tables, due to no longer having to
toggle them RW.

Tested-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191111132457.761255803@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/include/asm/ftrace.h | 2 +-
arch/x86/kernel/alternative.c | 18 +-
arch/x86/kernel/ftrace.c | 663 +++++----------------------------
arch/x86/kernel/traps.c | 9 +-
4 files changed, 134 insertions(+), 558 deletions(-)

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index c38a666..dbd9b08 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -34,8 +34,6 @@ 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 */
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 714b4a2..ce737f1 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -949,7 +949,7 @@ static struct bp_patching_desc {
int nr_entries;
} bp_patching;

-static int patch_cmp(const void *key, const void *elt)
+static int notrace patch_cmp(const void *key, const void *elt)
{
struct text_poke_loc *tp = (struct text_poke_loc *) elt;

@@ -961,7 +961,7 @@ static int patch_cmp(const void *key, const void *elt)
}
NOKPROBE_SYMBOL(patch_cmp);

-int poke_int3_handler(struct pt_regs *regs)
+int notrace poke_int3_handler(struct pt_regs *regs)
{
struct text_poke_loc *tp;
void *ip;
@@ -1209,10 +1209,15 @@ void text_poke_finish(void)
text_poke_flush(NULL);
}

-void text_poke_queue(void *addr, const void *opcode, size_t len, const void *emulate)
+void __ref text_poke_queue(void *addr, const void *opcode, size_t len, const void *emulate)
{
struct text_poke_loc *tp;

+ if (unlikely(system_state == SYSTEM_BOOTING)) {
+ text_poke_early(addr, opcode, len);
+ return;
+ }
+
text_poke_flush(addr);

tp = &tp_vec[tp_vec_nr++];
@@ -1230,10 +1235,15 @@ void text_poke_queue(void *addr, const void *opcode, size_t len, const void *emu
* dynamically allocated memory. This function should be used when it is
* not possible to allocate memory.
*/
-void text_poke_bp(void *addr, const void *opcode, size_t len, const void *emulate)
+void __ref text_poke_bp(void *addr, const void *opcode, size_t len, const void *emulate)
{
struct text_poke_loc tp;

+ if (unlikely(system_state == SYSTEM_BOOTING)) {
+ text_poke_early(addr, opcode, len);
+ return;
+ }
+
text_poke_loc_init(&tp, addr, opcode, len, emulate);
text_poke_bp_batch(&tp, 1);
}
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 024c305..3d8adeb 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -34,6 +34,8 @@

#ifdef CONFIG_DYNAMIC_FTRACE

+static int ftrace_poke_late = 0;
+
int ftrace_arch_code_modify_prepare(void)
__acquires(&text_mutex)
{
@@ -43,16 +45,20 @@ 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();
+ ftrace_poke_late = 1;
return 0;
}

int ftrace_arch_code_modify_post_process(void)
__releases(&text_mutex)
{
- set_all_modules_text_ro();
- set_kernel_text_ro();
+ /*
+ * ftrace_make_{call,nop}() may be called during
+ * module load, and we need to finish the text_poke_queue()
+ * that they do, here.
+ */
+ text_poke_finish();
+ ftrace_poke_late = 0;
mutex_unlock(&text_mutex);
return 0;
}
@@ -60,67 +66,34 @@ int ftrace_arch_code_modify_post_process(void)
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 const 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 const 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 const 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_verify_code(unsigned long ip, const char *old_code)
{
- unsigned char replaced[MCOUNT_INSN_SIZE];
-
- ftrace_expected = old_code;
+ char cur_code[MCOUNT_INSN_SIZE];

/*
* Note:
@@ -129,31 +102,41 @@ ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code,
* 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)) {
+ WARN_ON(1);
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) {
+ WARN_ON(1);
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;
+ return 0;
+}

- sync_core();
+static int
+ftrace_modify_code_direct(unsigned long ip, const char *old_code,
+ const char *new_code)
+{
+ int ret = ftrace_verify_code(ip, old_code);
+ if (ret)
+ return ret;

+ /* replace the text with the new text */
+ if (ftrace_poke_late)
+ text_poke_queue((void *)ip, new_code, MCOUNT_INSN_SIZE, NULL);
+ else
+ 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();
@@ -167,19 +150,20 @@ int ftrace_make_nop(struct module *mod,
* just modify the code directly.
*/
if (addr == MCOUNT_ADDR)
- return ftrace_modify_code_direct(rec->ip, old, new);
+ 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 +173,6 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
}

/*
- * 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 +184,84 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
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;
+ const char *new;

- 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);
+ ip = (unsigned long)(&ftrace_call);
+ new = ftrace_call_replace(ip, (unsigned long)func);
+ text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL);

- case FTRACE_UPDATE_MAKE_NOP:
- /* converting a call to a nop */
- return finish_update_nop(rec);
- }
+ ip = (unsigned long)(&ftrace_regs_call);
+ new = ftrace_call_replace(ip, (unsigned long)func);
+ 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 dyn_ftrace *rec;
- const char *report = "adding breakpoints";
- int count = 0;
+ const char *new, *old;
int ret;

for_ftrace_rec_iter(iter) {
rec = ftrace_rec_iter_record(iter);

- ret = add_breakpoints(rec, enable);
- if (ret)
- goto remove_breakpoints;
- count++;
- }
-
- run_sync();
+ switch (ftrace_test_record(rec, enable)) {
+ case FTRACE_UPDATE_IGNORE:
+ default:
+ continue;

- report = "updating code";
- count = 0;
+ case FTRACE_UPDATE_MAKE_CALL:
+ old = ftrace_nop_replace();
+ break;

- for_ftrace_rec_iter(iter) {
- rec = ftrace_rec_iter_record(iter);
+ case FTRACE_UPDATE_MODIFY_CALL:
+ case FTRACE_UPDATE_MAKE_NOP:
+ old = ftrace_call_replace(rec->ip, ftrace_get_addr_curr(rec));
+ break;
+ }

- ret = add_update(rec, enable);
- if (ret)
- goto remove_breakpoints;
- count++;
+ ret = ftrace_verify_code(rec->ip, old);
+ if (ret) {
+ ftrace_bug(ret, rec);
+ return;
+ }
}

- 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++;
- }
+ switch (ftrace_test_record(rec, enable)) {
+ case FTRACE_UPDATE_IGNORE:
+ default:
+ continue;

- run_sync();
+ case FTRACE_UPDATE_MAKE_CALL:
+ case FTRACE_UPDATE_MODIFY_CALL:
+ new = ftrace_call_replace(rec->ip, ftrace_get_addr_new(rec));
+ break;

- return;
+ 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();
+ text_poke_queue((void *)rec->ip, new, MCOUNT_INSN_SIZE, NULL);
+ ftrace_update_record(rec, enable);
}
- 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;
+ text_poke_finish();
}

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)
@@ -747,6 +326,7 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
unsigned long start_offset;
unsigned long end_offset;
unsigned long op_offset;
+ unsigned long call_offset;
unsigned long offset;
unsigned long npages;
unsigned long size;
@@ -763,10 +343,12 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
start_offset = (unsigned long)ftrace_regs_caller;
end_offset = (unsigned long)ftrace_regs_caller_end;
op_offset = (unsigned long)ftrace_regs_caller_op_ptr;
+ call_offset = (unsigned long)ftrace_regs_call;
} else {
start_offset = (unsigned long)ftrace_caller;
end_offset = (unsigned long)ftrace_epilogue;
op_offset = (unsigned long)ftrace_caller_op_ptr;
+ call_offset = (unsigned long)ftrace_call;
}

size = end_offset - start_offset;
@@ -823,16 +405,21 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
/* put in the new offset to the ftrace_ops */
memcpy(trampoline + op_offset, &op_ptr, OP_REF_SIZE);

+ /* put in the call to the function */
+ mutex_lock(&text_mutex);
+ call_offset -= start_offset;
+ memcpy(trampoline + call_offset,
+ text_gen_insn(CALL_INSN_OPCODE,
+ trampoline + call_offset,
+ ftrace_ops_get_func(ops)), CALL_INSN_SIZE);
+ mutex_unlock(&text_mutex);
+
/* ALLOC_TRAMP flags lets us know we created it */
ops->flags |= FTRACE_OPS_FL_ALLOC_TRAMP;

set_vm_flush_reset_perms(trampoline);

- /*
- * Module allocation needs to be completed by making the page
- * executable. The page is still writable, which is a security hazard,
- * but anyhow ftrace breaks W^X completely.
- */
+ set_memory_ro((unsigned long)trampoline, npages);
set_memory_x((unsigned long)trampoline, npages);
return (unsigned long)trampoline;
fail:
@@ -859,43 +446,35 @@ static unsigned long calc_trampoline_call_offset(bool save_regs)
void arch_ftrace_update_trampoline(struct ftrace_ops *ops)
{
ftrace_func_t func;
- unsigned char *new;
unsigned long offset;
unsigned long ip;
unsigned int size;
- int ret, npages;
+ const char *new;

- if (ops->trampoline) {
- /*
- * The ftrace_ops caller may set up its own trampoline.
- * In such a case, this code must not modify it.
- */
- if (!(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP))
- return;
- npages = PAGE_ALIGN(ops->trampoline_size) >> PAGE_SHIFT;
- set_memory_rw(ops->trampoline, npages);
- } else {
+ if (!ops->trampoline) {
ops->trampoline = create_trampoline(ops, &size);
if (!ops->trampoline)
return;
ops->trampoline_size = size;
- npages = PAGE_ALIGN(size) >> PAGE_SHIFT;
+ return;
}

+ /*
+ * The ftrace_ops caller may set up its own trampoline.
+ * In such a case, this code must not modify it.
+ */
+ if (!(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP))
+ return;
+
offset = calc_trampoline_call_offset(ops->flags & FTRACE_OPS_FL_SAVE_REGS);
ip = ops->trampoline + offset;
-
func = ftrace_ops_get_func(ops);

- ftrace_update_func_call = (unsigned long)func;
-
+ mutex_lock(&text_mutex);
/* Do a safe modify in case the trampoline is executing */
new = ftrace_call_replace(ip, (unsigned long)func);
- ret = update_ftrace_func(ip, new);
- set_memory_ro(ops->trampoline, npages);
-
- /* The update should never fail */
- WARN_ON(ret);
+ text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL);
+ mutex_unlock(&text_mutex);
}

/* Return the address of the function the trampoline calls */
@@ -981,19 +560,18 @@ void arch_ftrace_trampoline_free(struct ftrace_ops *ops)
#ifdef CONFIG_DYNAMIC_FTRACE
extern void ftrace_graph_call(void);

-static unsigned char *ftrace_jmp_replace(unsigned long ip, unsigned long addr)
+static const char *ftrace_jmp_replace(unsigned long ip, unsigned long addr)
{
- return ftrace_text_replace(0xe9, ip, addr);
+ return ftrace_text_replace(JMP32_INSN_OPCODE, ip, addr);
}

static int ftrace_mod_jmp(unsigned long ip, void *func)
{
- unsigned char *new;
+ const char *new;

- ftrace_update_func_call = 0UL;
new = ftrace_jmp_replace(ip, (unsigned long)func);
-
- return update_ftrace_func(ip, new);
+ text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL);
+ return 0;
}

int ftrace_enable_ftrace_graph_caller(void)
@@ -1019,10 +597,9 @@ int ftrace_disable_ftrace_graph_caller(void)
void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
unsigned long frame_pointer)
{
+ unsigned long return_hooker = (unsigned long)&return_to_handler;
unsigned long old;
int faulted;
- unsigned long return_hooker = (unsigned long)
- &return_to_handler;

/*
* When resuming from suspend-to-ram, this function can be indirectly
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 4bb0f84..c91d117 100644
--- 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;

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