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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 10/16] x86/alternative: Shrink text_poke_loc
Date: Fri, 18 Oct 2019 09:35:35 +0200	[thread overview]
Message-ID: <20191018074634.514629541@infradead.org> (raw)
In-Reply-To: <20191018073525.768931536@infradead.org>

Employ the fact that all text must be within a s32 displacement of one
another to shrink the text_poke_loc::addr field. Make it relative to
_stext.

This then shrinks struct text_poke_loc to 16 bytes, and consequently
increases TP_VEC_MAX from 170 to 256.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 arch/x86/kernel/alternative.c |   23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -937,7 +937,7 @@ static void do_sync_core(void *info)
 }
 
 struct text_poke_loc {
-	void *addr;
+	s32 rel_addr; /* addr := _stext + rel_addr */
 	s32 rel32;
 	u8 opcode;
 	const u8 text[POKE_MAX_OPCODE_SIZE];
@@ -948,13 +948,18 @@ static struct bp_patching_desc {
 	int nr_entries;
 } bp_patching;
 
+static inline void *text_poke_addr(struct text_poke_loc *tp)
+{
+	return _stext + tp->rel_addr;
+}
+
 static int notrace patch_cmp(const void *key, const void *elt)
 {
 	struct text_poke_loc *tp = (struct text_poke_loc *) elt;
 
-	if (key < tp->addr)
+	if (key < text_poke_addr(tp))
 		return -1;
-	if (key > tp->addr)
+	if (key > text_poke_addr(tp))
 		return 1;
 	return 0;
 }
@@ -1000,7 +1005,7 @@ int notrace poke_int3_handler(struct pt_
 			return 0;
 	} else {
 		tp = bp_patching.vec;
-		if (tp->addr != ip)
+		if (text_poke_addr(tp) != ip)
 			return 0;
 	}
 
@@ -1078,7 +1083,7 @@ static void text_poke_bp_batch(struct te
 	 * First step: add a int3 trap to the address that will be patched.
 	 */
 	for (i = 0; i < nr_entries; i++)
-		text_poke(tp[i].addr, &int3, sizeof(int3));
+		text_poke(text_poke_addr(&tp[i]), &int3, sizeof(int3));
 
 	on_each_cpu(do_sync_core, NULL, 1);
 
@@ -1089,7 +1094,7 @@ static void text_poke_bp_batch(struct te
 		int len = text_opcode_size(tp[i].opcode);
 
 		if (len - sizeof(int3) > 0) {
-			text_poke((char *)tp[i].addr + sizeof(int3),
+			text_poke(text_poke_addr(&tp[i]) + sizeof(int3),
 				  (const char *)tp[i].text + sizeof(int3),
 				  len - sizeof(int3));
 			do_sync++;
@@ -1113,7 +1118,7 @@ static void text_poke_bp_batch(struct te
 		if (tp[i].text[0] == INT3_INSN_OPCODE)
 			continue;
 
-		text_poke(tp[i].addr, tp[i].text, sizeof(int3));
+		text_poke(text_poke_addr(&tp[i]), tp[i].text, sizeof(int3));
 		do_sync++;
 	}
 
@@ -1143,7 +1148,7 @@ void text_poke_loc_init(struct text_poke
 	BUG_ON(!insn_complete(&insn));
 	BUG_ON(len != insn.length);
 
-	tp->addr = addr;
+	tp->rel_addr = addr - (void *)_stext;
 	tp->opcode = insn.opcode.bytes[0];
 
 	switch (tp->opcode) {
@@ -1192,7 +1197,7 @@ static bool tp_order_fail(void *addr)
 		return true;
 
 	tp = &tp_vec[tp_vec_nr - 1];
-	if ((unsigned long)tp->addr > (unsigned long)addr)
+	if ((unsigned long)text_poke_addr(tp) > (unsigned long)addr)
 		return true;
 
 	return false;



  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 ` [PATCH v4 04/16] x86/alternatives: Add and use text_gen_insn() helper Peter Zijlstra
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 ` Peter Zijlstra [this message]
2019-10-21  9:01   ` [PATCH v4 10/16] x86/alternative: Shrink text_poke_loc 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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