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From: Peter Zijlstra <peterz@infradead.org>
To: x86@kernel.org
Cc: peterz@infradead.org, linux-kernel@vger.kernel.org,
	rostedt@goodmis.org, mhiramat@kernel.org, bristot@redhat.com,
	jbaron@akamai.com, torvalds@linux-foundation.org,
	tglx@linutronix.de, mingo@kernel.org, namit@vmware.com,
	hpa@zytor.com, luto@kernel.org, ard.biesheuvel@linaro.org,
	jpoimboe@redhat.com, jeyu@kernel.org
Subject: [PATCH v4 04/16] x86/alternatives: Add and use text_gen_insn() helper
Date: Fri, 18 Oct 2019 09:35:29 +0200	[thread overview]
Message-ID: <20191018074634.170477322@infradead.org> (raw)
In-Reply-To: <20191018073525.768931536@infradead.org>

Provide a simple helper function to create common instruction
encodings.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
---
 arch/x86/include/asm/text-patching.h |    2 +
 arch/x86/kernel/alternative.c        |   36 +++++++++++++++++++++++++++++++++++
 arch/x86/kernel/jump_label.c         |   31 ++++++++++--------------------
 arch/x86/kernel/kprobes/opt.c        |    7 ------
 4 files changed, 50 insertions(+), 26 deletions(-)

--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -49,6 +49,8 @@ extern void text_poke_bp(void *addr, con
 extern void text_poke_queue(void *addr, const void *opcode, size_t len, const void *emulate);
 extern void text_poke_finish(void);
 
+extern void *text_gen_insn(u8 opcode, const void *addr, const void *dest);
+
 extern int after_bootmem;
 extern __ro_after_init struct mm_struct *poking_mm;
 extern __ro_after_init unsigned long poking_addr;
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -1237,3 +1237,39 @@ void text_poke_bp(void *addr, const void
 	text_poke_loc_init(&tp, addr, opcode, len, emulate);
 	text_poke_bp_batch(&tp, 1);
 }
+
+union text_poke_insn {
+	u8 text[POKE_MAX_OPCODE_SIZE];
+	struct {
+		u8 opcode;
+		s32 disp;
+	} __attribute__((packed));
+};
+
+void *text_gen_insn(u8 opcode, const void *addr, const void *dest)
+{
+	static union text_poke_insn insn; /* text_mutex */
+	int size = 0;
+
+	lockdep_assert_held(&text_mutex);
+
+	insn.opcode = opcode;
+
+#define __CASE(insn)	\
+	case insn##_INSN_OPCODE: size = insn##_INSN_SIZE; break
+
+	switch(opcode) {
+	__CASE(INT3);
+	__CASE(CALL);
+	__CASE(JMP32);
+	__CASE(JMP8);
+	}
+
+	if (size > 1) {
+		insn.disp = (long)dest - (long)(addr + size);
+		if (size == 2)
+			BUG_ON((insn.disp >> 31) != (insn.disp >> 7));
+	}
+
+	return &insn.text;
+}
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -16,15 +16,7 @@
 #include <asm/alternative.h>
 #include <asm/text-patching.h>
 
-union jump_code_union {
-	char code[JUMP_LABEL_NOP_SIZE];
-	struct {
-		char jump;
-		int offset;
-	} __attribute__((packed));
-};
-
-static void bug_at(unsigned char *ip, int line)
+static void bug_at(const void *ip, int line)
 {
 	/*
 	 * The location is not an op that we were expecting.
@@ -38,33 +30,32 @@ static void bug_at(unsigned char *ip, in
 static const void *
 __jump_label_set_jump_code(struct jump_entry *entry, enum jump_label_type type, int init)
 {
-	static union jump_code_union code; /* relies on text_mutex */
 	const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };
 	const unsigned char *ideal_nop = ideal_nops[NOP_ATOMIC5];
-	const void *expect;
+	const void *expect, *code;
+	const void *addr, *dest;
 	int line;
 
-	lockdep_assert_held(&text_mutex);
+	addr = (void *)jump_entry_code(entry);
+	dest = (void *)jump_entry_target(entry);
 
-	code.jump = JMP32_INSN_OPCODE;
-	code.offset = jump_entry_target(entry) -
-		       (jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);
+	code = text_gen_insn(JMP32_INSN_OPCODE, addr, dest);
 
 	if (init) {
 		expect = default_nop; line = __LINE__;
 	} else if (type == JUMP_LABEL_JMP) {
 		expect = ideal_nop; line = __LINE__;
 	} else {
-		expect = code.code; line = __LINE__;
+		expect = code; line = __LINE__;
 	}
 
-	if (memcmp((void *)jump_entry_code(entry), expect, JUMP_LABEL_NOP_SIZE))
-		bug_at((void *)jump_entry_code(entry), line);
+	if (memcmp(addr, expect, JUMP_LABEL_NOP_SIZE))
+		bug_at(addr, line);
 
 	if (type == JUMP_LABEL_NOP)
-		memcpy(&code, ideal_nop, JUMP_LABEL_NOP_SIZE);
+		code = ideal_nop;
 
-	return &code;
+	return code;
 }
 
 static void inline __jump_label_transform(struct jump_entry *entry,
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -447,18 +447,13 @@ void arch_optimize_kprobes(struct list_h
 void arch_unoptimize_kprobe(struct optimized_kprobe *op)
 {
 	u8 insn_buff[RELATIVEJUMP_SIZE];
-	u8 emulate_buff[RELATIVEJUMP_SIZE];
 
 	/* Set int3 to first byte for kprobes */
 	insn_buff[0] = BREAKPOINT_INSTRUCTION;
 	memcpy(insn_buff + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);
 
-	emulate_buff[0] = RELATIVEJUMP_OPCODE;
-	*(s32 *)(&emulate_buff[1]) = (s32)((long)op->optinsn.insn -
-			((long)op->kp.addr + RELATIVEJUMP_SIZE));
-
 	text_poke_bp(op->kp.addr, insn_buff, RELATIVEJUMP_SIZE,
-		     emulate_buff);
+		     text_gen_insn(JMP32_INSN_OPCODE, op->kp.addr, op->optinsn.insn));
 }
 
 /*



  parent reply	other threads:[~2019-10-18  7:53 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-18  7:35 [PATCH v4 00/16] Rewrite x86/ftrace to use text_poke (and more) Peter Zijlstra
2019-10-18  7:35 ` [PATCH v4 01/16] x86/alternatives: Teach text_poke_bp() to emulate instructions Peter Zijlstra
2019-10-18  7:35 ` [PATCH v4 02/16] x86/alternatives: Update int3_emulate_push() comment Peter Zijlstra
2019-10-18  7:35 ` [PATCH v4 03/16] x86/alternatives,jump_label: Provide better text_poke() batching interface Peter Zijlstra
2019-10-21  8:48   ` Ingo Molnar
2019-10-21  9:21     ` Peter Zijlstra
2019-10-18  7:35 ` Peter Zijlstra [this message]
2019-10-18  7:35 ` [PATCH v4 05/16] x86/ftrace: Use text_poke() Peter Zijlstra
2019-10-18  7:35 ` [PATCH v4 06/16] x86/mm: Remove set_kernel_text_r[ow]() Peter Zijlstra
2019-10-18  7:35 ` [PATCH v4 07/16] x86/alternative: Add text_opcode_size() Peter Zijlstra
2019-10-18  7:35 ` [PATCH v4 08/16] x86/ftrace: Use text_gen_insn() Peter Zijlstra
2019-10-18  7:35 ` [PATCH v4 09/16] x86/alternative: Remove text_poke_loc::len Peter Zijlstra
2019-10-21  8:58   ` Ingo Molnar
2019-10-21  9:02     ` Ingo Molnar
2019-10-18  7:35 ` [PATCH v4 10/16] x86/alternative: Shrink text_poke_loc Peter Zijlstra
2019-10-21  9:01   ` Ingo Molnar
2019-10-21  9:25     ` Peter Zijlstra
2019-10-21  9:33       ` Ingo Molnar
2019-10-18  7:35 ` [PATCH v4 11/16] x86/kprobes: Convert to text-patching.h Peter Zijlstra
2019-10-21 14:57   ` Masami Hiramatsu
2019-10-18  7:35 ` [PATCH v4 12/16] x86/kprobes: Fix ordering Peter Zijlstra
2019-10-22  1:35   ` Masami Hiramatsu
2019-10-22 10:31     ` Peter Zijlstra
2019-10-18  7:35 ` [PATCH v4 13/16] arm/ftrace: Use __patch_text_real() Peter Zijlstra
2019-10-28 16:25   ` Will Deacon
2019-10-28 16:34     ` Peter Zijlstra
2019-10-28 16:35       ` Peter Zijlstra
2019-10-28 16:47       ` Will Deacon
2019-10-28 16:55         ` Peter Zijlstra
2019-10-18  7:35 ` [PATCH v4 14/16] module: Remove set_all_modules_text_*() Peter Zijlstra
2019-10-18  7:35 ` [PATCH v4 15/16] module: Move where we mark modules RO,X Peter Zijlstra
2019-10-21 13:53   ` Josh Poimboeuf
2019-10-21 14:14     ` Peter Zijlstra
2019-10-21 15:34       ` Peter Zijlstra
2019-10-21 15:44         ` Peter Zijlstra
2019-10-21 16:11         ` Peter Zijlstra
2019-10-22 11:31           ` Heiko Carstens
2019-10-22 12:31             ` Peter Zijlstra
2019-10-23 11:48       ` Peter Zijlstra
2019-10-23 15:16         ` Peter Zijlstra
2019-10-23 17:15           ` Josh Poimboeuf
2019-10-24 10:59             ` Peter Zijlstra
2019-10-24 18:31               ` Josh Poimboeuf
2019-10-24 20:33                 ` Peter Zijlstra
2019-10-23 17:00         ` Josh Poimboeuf
2019-10-24 13:16           ` Peter Zijlstra
2019-10-25  6:44             ` Petr Mladek
2019-10-25  8:43               ` Peter Zijlstra
2019-10-25 10:06                 ` Peter Zijlstra
2019-10-25 13:50                   ` Josh Poimboeuf
2019-10-26  1:17                   ` Josh Poimboeuf
2019-10-28 10:07                     ` Peter Zijlstra
2019-10-28 10:43                     ` Peter Zijlstra
2019-10-25  9:16               ` Peter Zijlstra
2019-10-22  2:21   ` Steven Rostedt
2019-10-22 20:24     ` Peter Zijlstra
2019-10-22 20:40       ` Steven Rostedt
2019-10-23  9:07         ` Peter Zijlstra
2019-10-23 18:52       ` Steven Rostedt
2019-10-24 10:16         ` Peter Zijlstra
2019-10-24 10:18           ` Peter Zijlstra
2019-10-24 15:00           ` Steven Rostedt
2019-10-24 16:43             ` Peter Zijlstra
2019-10-24 18:17               ` Steven Rostedt
2019-10-24 20:24                 ` Peter Zijlstra
2019-10-24 20:28                   ` Steven Rostedt
2019-10-18  7:35 ` [PATCH v4 16/16] ftrace: Merge ftrace_module_{init,enable}() Peter Zijlstra
2019-10-18  8:20   ` Peter Zijlstra
2019-10-21  9:09 ` [PATCH v4 00/16] Rewrite x86/ftrace to use text_poke (and more) Ingo Molnar
2019-10-21 13:38   ` Steven Rostedt

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