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x86/ftrace: Use text_poke()

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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>
This commit is contained in:
Peter Zijlstra 2019-08-26 14:48:23 +02:00 committed by Ingo Molnar
parent 63f62addb8
commit 768ae4406a
4 changed files with 143 additions and 567 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

2
arch/x86/include/asm/ftrace.h
View file

@ -34,8 +34,6 @@ struct dyn_arch_ftrace {
/* No extra data needed for x86 */ /* No extra data needed for x86 */
}; };
int ftrace_int3_handler(struct pt_regs *regs);
#define FTRACE_GRAPH_TRAMP_ADDR FTRACE_GRAPH_ADDR #define FTRACE_GRAPH_TRAMP_ADDR FTRACE_GRAPH_ADDR
#endif /* CONFIG_DYNAMIC_FTRACE */ #endif /* CONFIG_DYNAMIC_FTRACE */

18
arch/x86/kernel/alternative.c
View file

@ -949,7 +949,7 @@ static struct bp_patching_desc {
int nr_entries; int nr_entries;
} bp_patching; } 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; 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); 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; struct text_poke_loc *tp;
void *ip; void *ip;
@ -1209,10 +1209,15 @@ void text_poke_finish(void)
text_poke_flush(NULL); 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; struct text_poke_loc *tp;
if (unlikely(system_state == SYSTEM_BOOTING)) {
text_poke_early(addr, opcode, len);
return;
}
text_poke_flush(addr); text_poke_flush(addr);
tp = &tp_vec[tp_vec_nr++]; 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 * dynamically allocated memory. This function should be used when it is
* not possible to allocate memory. * 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; 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_loc_init(&tp, addr, opcode, len, emulate);
text_poke_bp_batch(&tp, 1); text_poke_bp_batch(&tp, 1);
} }

681
arch/x86/kernel/ftrace.c
View file

@ -34,6 +34,8 @@
#ifdef CONFIG_DYNAMIC_FTRACE #ifdef CONFIG_DYNAMIC_FTRACE
static int ftrace_poke_late = 0;
int ftrace_arch_code_modify_prepare(void) int ftrace_arch_code_modify_prepare(void)
__acquires(&text_mutex) __acquires(&text_mutex)
{ {
@ -43,16 +45,20 @@ int ftrace_arch_code_modify_prepare(void)
* ftrace has it set to "read/write". * ftrace has it set to "read/write".
*/ */
mutex_lock(&text_mutex); mutex_lock(&text_mutex);
set_kernel_text_rw(); ftrace_poke_late = 1;
set_all_modules_text_rw();
return 0; return 0;
} }
int ftrace_arch_code_modify_post_process(void) int ftrace_arch_code_modify_post_process(void)
__releases(&text_mutex) __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); mutex_unlock(&text_mutex);
return 0; return 0;
} }
@ -60,67 +66,34 @@ int ftrace_arch_code_modify_post_process(void)
union ftrace_code_union { union ftrace_code_union {
char code[MCOUNT_INSN_SIZE]; char code[MCOUNT_INSN_SIZE];
struct { struct {
unsigned char op; char op;
int offset; int offset;
} __attribute__((packed)); } __attribute__((packed));
}; };
static int ftrace_calc_offset(long ip, long addr) static const char *ftrace_text_replace(char op, unsigned long ip, unsigned long addr)
{
return (int)(addr - ip);
}
static unsigned char *
ftrace_text_replace(unsigned char op, unsigned long ip, unsigned long addr)
{ {
static union ftrace_code_union calc; static union ftrace_code_union calc;
calc.op = op; calc.op = op;
calc.offset = ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr); calc.offset = (int)(addr - (ip + MCOUNT_INSN_SIZE));
return calc.code; return calc.code;
} }
static unsigned char * static const char *ftrace_nop_replace(void)
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)
{
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;
}
static const unsigned char *ftrace_nop_replace(void)
{ {
return ideal_nops[NOP_ATOMIC5]; return ideal_nops[NOP_ATOMIC5];
} }
static int static const char *ftrace_call_replace(unsigned long ip, unsigned long addr)
ftrace_modify_code_direct(unsigned long ip, unsigned const char *old_code,
unsigned const char *new_code)
{ {
unsigned char replaced[MCOUNT_INSN_SIZE]; return ftrace_text_replace(CALL_INSN_OPCODE, ip, addr);
}
ftrace_expected = old_code; static int ftrace_verify_code(unsigned long ip, const char *old_code)
{
char cur_code[MCOUNT_INSN_SIZE];
/* /*
* Note: * 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 * 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. * sure what we read is what we expected it to be before modifying it.
*/ */
/* read the text we want to modify */ /* 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; return -EFAULT;
}
/* Make sure it is what we expect it to be */ /* 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; 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();
return 0; return 0;
} }
int ftrace_make_nop(struct module *mod, static int
struct dyn_ftrace *rec, unsigned long addr) 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)
{ {
unsigned const char *new, *old;
unsigned long ip = rec->ip; unsigned long ip = rec->ip;
const char *new, *old;
old = ftrace_call_replace(ip, addr); old = ftrace_call_replace(ip, addr);
new = ftrace_nop_replace(); new = ftrace_nop_replace();
@ -167,19 +150,20 @@ int ftrace_make_nop(struct module *mod,
* just modify the code directly. * just modify the code directly.
*/ */
if (addr == MCOUNT_ADDR) if (addr == MCOUNT_ADDR)
return ftrace_modify_code_direct(rec->ip, old, new); return ftrace_modify_code_direct(ip, old, new);
ftrace_expected = NULL; /*
* x86 overrides ftrace_replace_code -- this function will never be used
/* Normal cases use add_brk_on_nop */ * in this case.
*/
WARN_ONCE(1, "invalid use of ftrace_make_nop"); WARN_ONCE(1, "invalid use of ftrace_make_nop");
return -EINVAL; return -EINVAL;
} }
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{ {
unsigned const char *new, *old;
unsigned long ip = rec->ip; unsigned long ip = rec->ip;
const char *new, *old;
old = ftrace_nop_replace(); old = ftrace_nop_replace();
new = ftrace_call_replace(ip, addr); new = ftrace_call_replace(ip, addr);
@ -188,43 +172,6 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
return ftrace_modify_code_direct(rec->ip, old, new); return ftrace_modify_code_direct(rec->ip, old, new);
} }
/*
* 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: * Should never be called:
* As it is only called by __ftrace_replace_code() which is called by * As it is only called by __ftrace_replace_code() which is called by
@ -237,452 +184,84 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
unsigned long addr) unsigned long addr)
{ {
WARN_ON(1); WARN_ON(1);
ftrace_expected = NULL;
return -EINVAL; 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) 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; unsigned long ip;
const char *new;
if (WARN_ON_ONCE(!regs)) ip = (unsigned long)(&ftrace_call);
return 0; new = ftrace_call_replace(ip, (unsigned long)func);
text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL);
ip = regs->ip - INT3_INSN_SIZE; ip = (unsigned long)(&ftrace_regs_call);
new = ftrace_call_replace(ip, (unsigned long)func);
if (ftrace_location(ip)) { text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL);
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; 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);
}
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) void ftrace_replace_code(int enable)
{ {
struct ftrace_rec_iter *iter; struct ftrace_rec_iter *iter;
struct dyn_ftrace *rec; struct dyn_ftrace *rec;
const char *report = "adding breakpoints"; const char *new, *old;
int count = 0;
int ret; int ret;
for_ftrace_rec_iter(iter) { for_ftrace_rec_iter(iter) {
rec = ftrace_rec_iter_record(iter); rec = ftrace_rec_iter_record(iter);
ret = add_breakpoints(rec, enable); switch (ftrace_test_record(rec, enable)) {
if (ret) case FTRACE_UPDATE_IGNORE:
goto remove_breakpoints; default:
count++; continue;
case FTRACE_UPDATE_MAKE_CALL:
old = ftrace_nop_replace();
break;
case FTRACE_UPDATE_MODIFY_CALL:
case FTRACE_UPDATE_MAKE_NOP:
old = ftrace_call_replace(rec->ip, ftrace_get_addr_curr(rec));
break;
}
ret = ftrace_verify_code(rec->ip, old);
if (ret) {
ftrace_bug(ret, rec);
return;
}
} }
run_sync();
report = "updating code";
count = 0;
for_ftrace_rec_iter(iter) { for_ftrace_rec_iter(iter) {
rec = ftrace_rec_iter_record(iter); rec = ftrace_rec_iter_record(iter);
ret = add_update(rec, enable); switch (ftrace_test_record(rec, enable)) {
if (ret) case FTRACE_UPDATE_IGNORE:
goto remove_breakpoints; default:
count++; continue;
case FTRACE_UPDATE_MAKE_CALL:
case FTRACE_UPDATE_MODIFY_CALL:
new = ftrace_call_replace(rec->ip, ftrace_get_addr_new(rec));
break;
case FTRACE_UPDATE_MAKE_NOP:
new = ftrace_nop_replace();
break;
}
text_poke_queue((void *)rec->ip, new, MCOUNT_INSN_SIZE, NULL);
ftrace_update_record(rec, enable);
} }
text_poke_finish();
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();
return;
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();
}
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) 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); ftrace_modify_all_code(command);
atomic_dec(&modifying_ftrace_code);
} }
int __init ftrace_dyn_arch_init(void) 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 start_offset;
unsigned long end_offset; unsigned long end_offset;
unsigned long op_offset; unsigned long op_offset;
unsigned long call_offset;
unsigned long offset; unsigned long offset;
unsigned long npages; unsigned long npages;
unsigned long size; unsigned long size;
@ -763,10 +343,12 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
start_offset = (unsigned long)ftrace_regs_caller; start_offset = (unsigned long)ftrace_regs_caller;
end_offset = (unsigned long)ftrace_regs_caller_end; end_offset = (unsigned long)ftrace_regs_caller_end;
op_offset = (unsigned long)ftrace_regs_caller_op_ptr; op_offset = (unsigned long)ftrace_regs_caller_op_ptr;
call_offset = (unsigned long)ftrace_regs_call;
} else { } else {
start_offset = (unsigned long)ftrace_caller; start_offset = (unsigned long)ftrace_caller;
end_offset = (unsigned long)ftrace_epilogue; end_offset = (unsigned long)ftrace_epilogue;
op_offset = (unsigned long)ftrace_caller_op_ptr; op_offset = (unsigned long)ftrace_caller_op_ptr;
call_offset = (unsigned long)ftrace_call;
} }
size = end_offset - start_offset; 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 */ /* put in the new offset to the ftrace_ops */
memcpy(trampoline + op_offset, &op_ptr, OP_REF_SIZE); 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 */ /* ALLOC_TRAMP flags lets us know we created it */
ops->flags |= FTRACE_OPS_FL_ALLOC_TRAMP; ops->flags |= FTRACE_OPS_FL_ALLOC_TRAMP;
set_vm_flush_reset_perms(trampoline); set_vm_flush_reset_perms(trampoline);
/* set_memory_ro((unsigned long)trampoline, npages);
* 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_x((unsigned long)trampoline, npages); set_memory_x((unsigned long)trampoline, npages);
return (unsigned long)trampoline; return (unsigned long)trampoline;
fail: fail:
@ -859,43 +446,35 @@ static unsigned long calc_trampoline_call_offset(bool save_regs)
void arch_ftrace_update_trampoline(struct ftrace_ops *ops) void arch_ftrace_update_trampoline(struct ftrace_ops *ops)
{ {
ftrace_func_t func; ftrace_func_t func;
unsigned char *new;
unsigned long offset; unsigned long offset;
unsigned long ip; unsigned long ip;
unsigned int size; unsigned int size;
int ret, npages; const char *new;
if (ops->trampoline) { 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 {
ops->trampoline = create_trampoline(ops, &size); ops->trampoline = create_trampoline(ops, &size);
if (!ops->trampoline) if (!ops->trampoline)
return; return;
ops->trampoline_size = size; 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); offset = calc_trampoline_call_offset(ops->flags & FTRACE_OPS_FL_SAVE_REGS);
ip = ops->trampoline + offset; ip = ops->trampoline + offset;
func = ftrace_ops_get_func(ops); 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 */ /* Do a safe modify in case the trampoline is executing */
new = ftrace_call_replace(ip, (unsigned long)func); new = ftrace_call_replace(ip, (unsigned long)func);
ret = update_ftrace_func(ip, new); text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL);
set_memory_ro(ops->trampoline, npages); mutex_unlock(&text_mutex);
/* The update should never fail */
WARN_ON(ret);
} }
/* Return the address of the function the trampoline calls */ /* 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 #ifdef CONFIG_DYNAMIC_FTRACE
extern void ftrace_graph_call(void); 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) 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); new = ftrace_jmp_replace(ip, (unsigned long)func);
text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL);
return update_ftrace_func(ip, new); return 0;
} }
int ftrace_enable_ftrace_graph_caller(void) 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, void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
unsigned long frame_pointer) unsigned long frame_pointer)
{ {
unsigned long return_hooker = (unsigned long)&return_to_handler;
unsigned long old; unsigned long old;
int faulted; int faulted;
unsigned long return_hooker = (unsigned long)
&return_to_handler;
/* /*
* When resuming from suspend-to-ram, this function can be indirectly * When resuming from suspend-to-ram, this function can be indirectly

9
arch/x86/kernel/traps.c
View file

@ -563,15 +563,6 @@ NOKPROBE_SYMBOL(do_general_protection);
dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code) 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)) if (poke_int3_handler(regs))
return; return;