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From: peterz at infradead.org (Peter Zijlstra)
Subject: [RFC][PATCH] ftrace/x86: Emulate call function while updating in breakpoint handler
Date: Wed, 1 May 2019 15:11:17 +0200	[thread overview]
Message-ID: <20190501131117.GW2623@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CAHk-=wjJ8D74+FDcXGL65Q9aB0cc7B4vr2s2rS6V4d4a3hU-1Q@mail.gmail.com>

On Tue, Apr 30, 2019 at 11:33:21AM -0700, Linus Torvalds wrote:
> Anyway, since Andy really likes the entry code change, can we have
> that patch in parallel and judge the difference that way? Iirc, that
> was x86-64 specific too.

Here goes, compile tested only...

It obviously needs a self-test, but that shoulnd't be too hard to
arrange.

---
 arch/x86/entry/entry_32.S            |  7 +++++++
 arch/x86/entry/entry_64.S            | 14 ++++++++++++--
 arch/x86/include/asm/text-patching.h | 20 ++++++++++++++++++++
 arch/x86/kernel/ftrace.c             | 24 +++++++++++++++++++-----
 4 files changed, 58 insertions(+), 7 deletions(-)

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 7b23431be5cb..d246302085a3 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -1479,6 +1479,13 @@ ENTRY(int3)
 	ASM_CLAC
 	pushl	$-1				# mark this as an int
 
+	testl	$SEGMENT_RPL_MASK, PT_CS(%esp)
+	jnz	.Lfrom_usermode_no_gap
+	.rept 6
+	pushl	5*4(%esp)
+	.endr
+.Lfrom_usermode_no_gap:
+
 	SAVE_ALL switch_stacks=1
 	ENCODE_FRAME_POINTER
 	TRACE_IRQS_OFF
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 20e45d9b4e15..268cd9affe04 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -878,7 +878,7 @@ apicinterrupt IRQ_WORK_VECTOR			irq_work_interrupt		smp_irq_work_interrupt
  * @paranoid == 2 is special: the stub will never switch stacks.  This is for
  * #DF: if the thread stack is somehow unusable, we'll still get a useful OOPS.
  */
-.macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1 ist_offset=0
+.macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1 ist_offset=0 create_gap=0
 ENTRY(\sym)
 	UNWIND_HINT_IRET_REGS offset=\has_error_code*8
 
@@ -898,6 +898,16 @@ ENTRY(\sym)
 	jnz	.Lfrom_usermode_switch_stack_\@
 	.endif
 
+	.if \create_gap == 1
+	testb	$3, CS-ORIG_RAX(%rsp)
+	jnz	.Lfrom_usermode_no_gap_\@
+	.rept 6
+	pushq	5*8(%rsp)
+	.endr
+	UNWIND_HINT_IRET_REGS offset=8
+.Lfrom_usermode_no_gap_\@:
+	.endif
+
 	.if \paranoid
 	call	paranoid_entry
 	.else
@@ -1129,7 +1139,7 @@ apicinterrupt3 HYPERV_STIMER0_VECTOR \
 #endif /* CONFIG_HYPERV */
 
 idtentry debug			do_debug		has_error_code=0	paranoid=1 shift_ist=IST_INDEX_DB ist_offset=DB_STACK_OFFSET
-idtentry int3			do_int3			has_error_code=0
+idtentry int3			do_int3			has_error_code=0	create_gap=1
 idtentry stack_segment		do_stack_segment	has_error_code=1
 
 #ifdef CONFIG_XEN_PV
diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h
index e85ff65c43c3..ba275b6292db 100644
--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -39,4 +39,24 @@ extern int poke_int3_handler(struct pt_regs *regs);
 extern void *text_poke_bp(void *addr, const void *opcode, size_t len, void *handler);
 extern int after_bootmem;
 
+static inline void int3_emulate_push(struct pt_regs *regs, unsigned long val)
+{
+	regs->sp -= sizeof(unsigned long);
+	*(unsigned long *)regs->sp = val;
+}
+
+static inline void int3_emulate_jmp(struct pt_regs *regs, unsigned long ip)
+{
+	regs->ip = ip;
+}
+
+#define INT3_INSN_SIZE 1
+#define CALL_INSN_SIZE 5
+
+static inline void int3_emulate_call(struct pt_regs *regs, unsigned long func)
+{
+	int3_emulate_push(regs, regs->ip - INT3_INSN_SIZE + CALL_INSN_SIZE);
+	int3_emulate_jmp(regs, func);
+}
+
 #endif /* _ASM_X86_TEXT_PATCHING_H */
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index ef49517f6bb2..90d319687d7e 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -29,6 +29,7 @@
 #include <asm/kprobes.h>
 #include <asm/ftrace.h>
 #include <asm/nops.h>
+#include <asm/text-patching.h>
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 
@@ -231,6 +232,7 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
 }
 
 static unsigned long ftrace_update_func;
+static unsigned long ftrace_update_func_call;
 
 static int update_ftrace_func(unsigned long ip, void *new)
 {
@@ -259,6 +261,8 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 	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);
 
@@ -295,12 +299,19 @@ int ftrace_int3_handler(struct pt_regs *regs)
 		return 0;
 
 	ip = regs->ip - 1;
-	if (!ftrace_location(ip) && !is_ftrace_caller(ip))
-		return 0;
-
-	regs->ip += MCOUNT_INSN_SIZE - 1;
+	if (ftrace_location(ip)) {
+		int3_emulate_call(regs, ftrace_update_func_call);
+		return 1;
+	} else if (is_ftrace_caller(ip)) {
+		if (!ftrace_update_func_call) {
+			int3_emulate_jmp(regs, regs->ip - INT3_INSN_SIZE + CALL_INSN_SIZE);
+			return 1;
+		}
+		int3_emulate_call(regs, ftrace_update_func_call);
+		return 1;
+	}
 
-	return 1;
+	return 0;
 }
 NOKPROBE_SYMBOL(ftrace_int3_handler);
 
@@ -859,6 +870,8 @@ void arch_ftrace_update_trampoline(struct ftrace_ops *ops)
 
 	func = ftrace_ops_get_func(ops);
 
+	ftrace_update_func_call = (unsigned long)func;
+
 	/* Do a safe modify in case the trampoline is executing */
 	new = ftrace_call_replace(ip, (unsigned long)func);
 	ret = update_ftrace_func(ip, new);
@@ -960,6 +973,7 @@ static int ftrace_mod_jmp(unsigned long ip, void *func)
 {
 	unsigned char *new;
 
+	ftrace_update_func_call = 0UL;
 	new = ftrace_jmp_replace(ip, (unsigned long)func);
 
 	return update_ftrace_func(ip, new);

WARNING: multiple messages have this Message-ID (diff)
From: peterz@infradead.org (Peter Zijlstra)
Subject: [RFC][PATCH] ftrace/x86: Emulate call function while updating in breakpoint handler
Date: Wed, 1 May 2019 15:11:17 +0200	[thread overview]
Message-ID: <20190501131117.GW2623@hirez.programming.kicks-ass.net> (raw)
Message-ID: <20190501131117.ncGnFPk-I3h5gVA7fZej_iLih7jsg9gqhSxnioHczww@z> (raw)
In-Reply-To: <CAHk-=wjJ8D74+FDcXGL65Q9aB0cc7B4vr2s2rS6V4d4a3hU-1Q@mail.gmail.com>

On Tue, Apr 30, 2019@11:33:21AM -0700, Linus Torvalds wrote:
> Anyway, since Andy really likes the entry code change, can we have
> that patch in parallel and judge the difference that way? Iirc, that
> was x86-64 specific too.

Here goes, compile tested only...

It obviously needs a self-test, but that shoulnd't be too hard to
arrange.

---
 arch/x86/entry/entry_32.S            |  7 +++++++
 arch/x86/entry/entry_64.S            | 14 ++++++++++++--
 arch/x86/include/asm/text-patching.h | 20 ++++++++++++++++++++
 arch/x86/kernel/ftrace.c             | 24 +++++++++++++++++++-----
 4 files changed, 58 insertions(+), 7 deletions(-)

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 7b23431be5cb..d246302085a3 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -1479,6 +1479,13 @@ ENTRY(int3)
 	ASM_CLAC
 	pushl	$-1				# mark this as an int
 
+	testl	$SEGMENT_RPL_MASK, PT_CS(%esp)
+	jnz	.Lfrom_usermode_no_gap
+	.rept 6
+	pushl	5*4(%esp)
+	.endr
+.Lfrom_usermode_no_gap:
+
 	SAVE_ALL switch_stacks=1
 	ENCODE_FRAME_POINTER
 	TRACE_IRQS_OFF
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 20e45d9b4e15..268cd9affe04 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -878,7 +878,7 @@ apicinterrupt IRQ_WORK_VECTOR			irq_work_interrupt		smp_irq_work_interrupt
  * @paranoid == 2 is special: the stub will never switch stacks.  This is for
  * #DF: if the thread stack is somehow unusable, we'll still get a useful OOPS.
  */
-.macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1 ist_offset=0
+.macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1 ist_offset=0 create_gap=0
 ENTRY(\sym)
 	UNWIND_HINT_IRET_REGS offset=\has_error_code*8
 
@@ -898,6 +898,16 @@ ENTRY(\sym)
 	jnz	.Lfrom_usermode_switch_stack_\@
 	.endif
 
+	.if \create_gap == 1
+	testb	$3, CS-ORIG_RAX(%rsp)
+	jnz	.Lfrom_usermode_no_gap_\@
+	.rept 6
+	pushq	5*8(%rsp)
+	.endr
+	UNWIND_HINT_IRET_REGS offset=8
+.Lfrom_usermode_no_gap_\@:
+	.endif
+
 	.if \paranoid
 	call	paranoid_entry
 	.else
@@ -1129,7 +1139,7 @@ apicinterrupt3 HYPERV_STIMER0_VECTOR \
 #endif /* CONFIG_HYPERV */
 
 idtentry debug			do_debug		has_error_code=0	paranoid=1 shift_ist=IST_INDEX_DB ist_offset=DB_STACK_OFFSET
-idtentry int3			do_int3			has_error_code=0
+idtentry int3			do_int3			has_error_code=0	create_gap=1
 idtentry stack_segment		do_stack_segment	has_error_code=1
 
 #ifdef CONFIG_XEN_PV
diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h
index e85ff65c43c3..ba275b6292db 100644
--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -39,4 +39,24 @@ extern int poke_int3_handler(struct pt_regs *regs);
 extern void *text_poke_bp(void *addr, const void *opcode, size_t len, void *handler);
 extern int after_bootmem;
 
+static inline void int3_emulate_push(struct pt_regs *regs, unsigned long val)
+{
+	regs->sp -= sizeof(unsigned long);
+	*(unsigned long *)regs->sp = val;
+}
+
+static inline void int3_emulate_jmp(struct pt_regs *regs, unsigned long ip)
+{
+	regs->ip = ip;
+}
+
+#define INT3_INSN_SIZE 1
+#define CALL_INSN_SIZE 5
+
+static inline void int3_emulate_call(struct pt_regs *regs, unsigned long func)
+{
+	int3_emulate_push(regs, regs->ip - INT3_INSN_SIZE + CALL_INSN_SIZE);
+	int3_emulate_jmp(regs, func);
+}
+
 #endif /* _ASM_X86_TEXT_PATCHING_H */
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index ef49517f6bb2..90d319687d7e 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -29,6 +29,7 @@
 #include <asm/kprobes.h>
 #include <asm/ftrace.h>
 #include <asm/nops.h>
+#include <asm/text-patching.h>
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 
@@ -231,6 +232,7 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
 }
 
 static unsigned long ftrace_update_func;
+static unsigned long ftrace_update_func_call;
 
 static int update_ftrace_func(unsigned long ip, void *new)
 {
@@ -259,6 +261,8 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 	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);
 
@@ -295,12 +299,19 @@ int ftrace_int3_handler(struct pt_regs *regs)
 		return 0;
 
 	ip = regs->ip - 1;
-	if (!ftrace_location(ip) && !is_ftrace_caller(ip))
-		return 0;
-
-	regs->ip += MCOUNT_INSN_SIZE - 1;
+	if (ftrace_location(ip)) {
+		int3_emulate_call(regs, ftrace_update_func_call);
+		return 1;
+	} else if (is_ftrace_caller(ip)) {
+		if (!ftrace_update_func_call) {
+			int3_emulate_jmp(regs, regs->ip - INT3_INSN_SIZE + CALL_INSN_SIZE);
+			return 1;
+		}
+		int3_emulate_call(regs, ftrace_update_func_call);
+		return 1;
+	}
 
-	return 1;
+	return 0;
 }
 NOKPROBE_SYMBOL(ftrace_int3_handler);
 
@@ -859,6 +870,8 @@ void arch_ftrace_update_trampoline(struct ftrace_ops *ops)
 
 	func = ftrace_ops_get_func(ops);
 
+	ftrace_update_func_call = (unsigned long)func;
+
 	/* Do a safe modify in case the trampoline is executing */
 	new = ftrace_call_replace(ip, (unsigned long)func);
 	ret = update_ftrace_func(ip, new);
@@ -960,6 +973,7 @@ static int ftrace_mod_jmp(unsigned long ip, void *func)
 {
 	unsigned char *new;
 
+	ftrace_update_func_call = 0UL;
 	new = ftrace_jmp_replace(ip, (unsigned long)func);
 
 	return update_ftrace_func(ip, new);

  parent reply	other threads:[~2019-05-01 13:11 UTC|newest]

Thread overview: 128+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-27 10:06 [PATCH 0/4] x86/ftrace: make ftrace_int3_handler() not to skip fops invocation nstange
2019-04-27 10:06 ` Nicolai Stange
2019-04-27 10:06 ` [PATCH 1/4] x86/thread_info: introduce ->ftrace_int3_stack member nstange
2019-04-27 10:06   ` Nicolai Stange
2019-04-28 17:41   ` luto
2019-04-28 17:41     ` Andy Lutomirski
2019-04-28 17:51     ` rostedt
2019-04-28 17:51       ` Steven Rostedt
2019-04-28 18:08       ` luto
2019-04-28 18:08         ` Andy Lutomirski
2019-04-28 19:43         ` rostedt
2019-04-28 19:43           ` Steven Rostedt
2019-04-28 20:56           ` luto
2019-04-28 20:56             ` Andy Lutomirski
2019-04-28 21:22       ` nstange
2019-04-28 21:22         ` Nicolai Stange
2019-04-28 23:27         ` luto
2019-04-28 23:27           ` Andy Lutomirski
2019-04-27 10:06 ` [PATCH 2/4] ftrace: drop 'static' qualifier from ftrace_ops_list_func() nstange
2019-04-27 10:06   ` Nicolai Stange
2019-04-27 10:06 ` [PATCH 3/4] x86/ftrace: make ftrace_int3_handler() not to skip fops invocation nstange
2019-04-27 10:06   ` Nicolai Stange
2019-04-27 10:26   ` peterz
2019-04-27 10:26     ` Peter Zijlstra
2019-04-28 17:38     ` rostedt
2019-04-28 17:38       ` Steven Rostedt
2019-04-29 18:06       ` torvalds
2019-04-29 18:06         ` Linus Torvalds
2019-04-29 18:22         ` torvalds
2019-04-29 18:22           ` Linus Torvalds
2019-04-29 18:42           ` luto
2019-04-29 18:42             ` Andy Lutomirski
     [not found]             ` <CAHk-=whtt4K2f0KPtG-4Pykh3FK8UBOjD8jhXCUKB5nWDj_YRA@mail.gmail.com>
2019-04-29 18:56               ` luto
2019-04-29 18:56                 ` Andy Lutomirski
     [not found]                 ` <CAHk-=wgewK4eFhF3=0RNtk1KQjMANFH6oDE=8m=84RExn2gxhw@mail.gmail.com>
     [not found]                   ` <CAHk-=whay7eN6+2gZjY-ybRbkbcqAmgrLwwszzHx8ws3c=S-MA@mail.gmail.com>
2019-04-29 19:24                     ` luto
2019-04-29 19:24                       ` Andy Lutomirski
2019-04-29 20:07                       ` torvalds
2019-04-29 20:07                         ` Linus Torvalds
2019-04-30 13:56                         ` peterz
2019-04-30 13:56                           ` Peter Zijlstra
2019-04-30 16:06                           ` torvalds
2019-04-30 16:06                             ` Linus Torvalds
2019-04-30 16:33                             ` luto
2019-04-30 16:33                               ` Andy Lutomirski
2019-04-30 17:03                               ` rostedt
2019-04-30 17:03                                 ` Steven Rostedt
2019-04-30 17:20                                 ` rostedt
2019-04-30 17:20                                   ` Steven Rostedt
2019-04-30 17:49                                   ` [RFC][PATCH] ftrace/x86: Emulate call function while updating in breakpoint handler rostedt
2019-04-30 17:49                                     ` Steven Rostedt
2019-04-30 18:33                                     ` torvalds
2019-04-30 18:33                                       ` Linus Torvalds
2019-04-30 19:00                                       ` rostedt
2019-04-30 19:00                                         ` Steven Rostedt
2019-04-30 21:08                                       ` rostedt
2019-04-30 21:08                                         ` Steven Rostedt
2019-05-01 13:11                                       ` peterz [this message]
2019-05-01 13:11                                         ` Peter Zijlstra
2019-05-01 18:58                                         ` rostedt
2019-05-01 18:58                                           ` Steven Rostedt
2019-05-01 19:03                                           ` peterz
2019-05-01 19:03                                             ` Peter Zijlstra
2019-05-01 19:03                                         ` torvalds
2019-05-01 19:03                                           ` Linus Torvalds
2019-05-01 19:13                                           ` peterz
2019-05-01 19:13                                             ` Peter Zijlstra
2019-05-01 19:13                                           ` rostedt
2019-05-01 19:13                                             ` Steven Rostedt
2019-05-01 19:33                                             ` jikos
2019-05-01 19:33                                               ` Jiri Kosina
2019-05-01 19:41                                               ` peterz
2019-05-01 19:41                                                 ` Peter Zijlstra
2019-04-30 21:53                                     ` [RFC][PATCH v2] " rostedt
2019-04-30 21:53                                       ` Steven Rostedt
2019-05-01  1:35                                       ` rostedt
2019-05-01  1:35                                         ` Steven Rostedt
2019-05-01  1:58                                         ` torvalds
2019-05-01  1:58                                           ` Linus Torvalds
2019-05-01  8:26                                       ` nstange
2019-05-01  8:26                                         ` Nicolai Stange
2019-05-01 13:22                                         ` rostedt
2019-05-01 13:22                                           ` Steven Rostedt
2019-04-29 20:16                   ` [PATCH 3/4] x86/ftrace: make ftrace_int3_handler() not to skip fops invocation torvalds
2019-04-29 20:16                     ` Linus Torvalds
2019-04-29 22:08                     ` sean.j.christopherson
2019-04-29 22:08                       ` Sean Christopherson
2019-04-29 22:22                       ` torvalds
2019-04-29 22:22                         ` Linus Torvalds
2019-04-30  0:08                         ` sean.j.christopherson
2019-04-30  0:08                           ` Sean Christopherson
2019-04-30  0:45                           ` sean.j.christopherson
2019-04-30  0:45                             ` Sean Christopherson
2019-04-30  2:26                             ` torvalds
2019-04-30  2:26                               ` Linus Torvalds
2019-04-30 10:40                               ` peterz
2019-04-30 10:40                                 ` Peter Zijlstra
2019-04-30 11:17                               ` jikos
2019-04-30 11:17                                 ` Jiri Kosina
2019-04-29 22:06                 ` torvalds
2019-04-29 22:06                   ` Linus Torvalds
2019-04-30 11:18                   ` peterz
2019-04-30 11:18                     ` Peter Zijlstra
2019-04-29 18:52         ` rostedt
2019-04-29 18:52           ` Steven Rostedt
     [not found]           ` <CAHk-=wjm93jLtVxTX4HZs6K4k1Wqh3ujjmapqaYtcibVk_YnzQ@mail.gmail.com>
2019-04-29 19:07             ` rostedt
2019-04-29 19:07               ` Steven Rostedt
2019-04-29 20:06               ` torvalds
2019-04-29 20:06                 ` Linus Torvalds
2019-04-29 20:20                 ` torvalds
2019-04-29 20:20                   ` Linus Torvalds
2019-04-29 20:30                 ` rostedt
2019-04-29 20:30                   ` Steven Rostedt
2019-04-29 21:38                   ` torvalds
2019-04-29 21:38                     ` Linus Torvalds
2019-04-29 22:07                     ` rostedt
2019-04-29 22:07                       ` Steven Rostedt
2019-04-30  9:24                       ` nstange
2019-04-30  9:24                         ` Nicolai Stange
2019-04-30 10:46           ` peterz
2019-04-30 10:46             ` Peter Zijlstra
2019-04-30 13:44             ` rostedt
2019-04-30 13:44               ` Steven Rostedt
2019-04-30 14:20               ` peterz
2019-04-30 14:20                 ` Peter Zijlstra
2019-04-30 14:36                 ` rostedt
2019-04-30 14:36                   ` Steven Rostedt
2019-04-27 10:06 ` [PATCH 4/4] selftests/livepatch: add "ftrace a live patched function" test nstange
2019-04-27 10:06   ` Nicolai Stange

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