x86/ftrace: Use text_poke() (768ae440) · Commits · EulixOS / Software / Kernel

arch/x86/include/asm/ftrace.h

+0 −2

Original line number	Diff line number	Diff line
		@@ -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 */

arch/x86/kernel/alternative.c

+14 −4

Original line number	Diff line number	Diff line
		@@ -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);
		}

arch/x86/kernel/ftrace.c

+120 −543

Original line number	Diff line number	Diff line
		@@ -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.offset = (int)(addr - (ip + MCOUNT_INSN_SIZE));

		return calc.code;
		}

		static unsigned char *
		ftrace_call_replace(unsigned long ip, unsigned long addr)
		static const char *ftrace_nop_replace(void)
		{
		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;
		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);

		ftrace_expected = NULL;
		return ftrace_modify_code_direct(ip, old, new);

		/* 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);
		@@ -188,43 +172,6 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
		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:
		* 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)
		{
		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;
		unsigned long ip;
		const char *new;

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

		/* 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;
		}
		text_poke_bp((void *)ip, new, MCOUNT_INSN_SIZE, NULL);

		/*
		* 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)
		void ftrace_replace_code(int enable)
		{
		unsigned long ftrace_addr;
		struct ftrace_rec_iter *iter;
		struct dyn_ftrace *rec;
		const char new, old;
		int ret;

		ftrace_addr = ftrace_get_addr_curr(rec);

		ret = ftrace_test_record(rec, enable);
		for_ftrace_rec_iter(iter) {
		rec = ftrace_rec_iter_record(iter);

		switch (ret) {
		switch (ftrace_test_record(rec, enable)) {
		case FTRACE_UPDATE_IGNORE:
		return 0;
		default:
		continue;

		case FTRACE_UPDATE_MAKE_CALL:
		/* converting nop to call */
		return add_brk_on_nop(rec);
		old = ftrace_nop_replace();
		break;

		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);
		old = ftrace_call_replace(rec->ip, ftrace_get_addr_curr(rec));
		break;
		}

		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);
		ret = ftrace_verify_code(rec->ip, old);
		if (ret) {
		ftrace_bug(ret, rec);
		return;
		}

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

		switch (ret) {
		switch (ftrace_test_record(rec, enable)) {
		case FTRACE_UPDATE_IGNORE:
		return 0;
		default:
		continue;

		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);
		new = ftrace_call_replace(rec->ip, ftrace_get_addr_new(rec));
		break;

		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)
		{
		struct ftrace_rec_iter *iter;
		struct dyn_ftrace *rec;
		const char *report = "adding breakpoints";
		int count = 0;
		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();

		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++;
		new = ftrace_nop_replace();
		break;
		}

		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();
		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) {
		ops->trampoline = create_trampoline(ops, &size);
		if (!ops->trampoline)
		return;
		ops->trampoline_size = size;
		return;
		}

		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);
		if (!ops->trampoline)
		return;
		ops->trampoline_size = size;
		npages = PAGE_ALIGN(size) >> PAGE_SHIFT;
		}

		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

arch/x86/kernel/traps.c

+0 −9

Original line number	Diff line number	Diff line
		@@ -563,15 +563,6 @@ 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;