linux-kernel - [PATCH 05/13] jump_label, x86: Improve error when we fail expected text

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Date:   Thu, 06 May 2021 21:33:57 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     x86@...nel.org, jpoimboe@...hat.com, jbaron@...mai.com,
        rostedt@...dmis.org, ardb@...nel.org
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org
Subject: [PATCH 05/13] jump_label, x86: Improve error when we fail expected text

There is only a single usage site left, remove the function and extend
the print to include more information, like the expected text and the
patch type.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/x86/kernel/jump_label.c |   33 ++++++++++++++-------------------
 1 file changed, 14 insertions(+), 19 deletions(-)

--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -16,38 +16,33 @@
 #include <asm/alternative.h>
 #include <asm/text-patching.h>
 
-static void bug_at(const void *ip, int line)
-{
-	/*
-	 * The location is not an op that we were expecting.
-	 * Something went wrong. Crash the box, as something could be
-	 * corrupting the kernel.
-	 */
-	pr_crit("jump_label: Fatal kernel bug, unexpected op at %pS [%p] (%5ph) %d\n", ip, ip, ip, line);
-	BUG();
-}
-
 static const void *
 __jump_label_set_jump_code(struct jump_entry *entry, enum jump_label_type type)
 {
 	const void *expect, *code;
 	const void *addr, *dest;
-	int line;
 
 	addr = (void *)jump_entry_code(entry);
 	dest = (void *)jump_entry_target(entry);
 
 	code = text_gen_insn(JMP32_INSN_OPCODE, addr, dest);
 
-	if (type == JUMP_LABEL_JMP) {
-		expect = x86_nops[5]; line = __LINE__;
-	} else {
-		expect = code; line = __LINE__;
+	if (type == JUMP_LABEL_JMP)
+		expect = x86_nops[5];
+	else
+		expect = code;
+
+	if (memcmp(addr, expect, JUMP_LABEL_NOP_SIZE)) {
+		/*
+		 * The location is not an op that we were expecting.
+		 * Something went wrong. Crash the box, as something could be
+		 * corrupting the kernel.
+		 */
+		pr_crit("jump_label: Fatal kernel bug, unexpected op at %pS [%p] (%5ph != %5ph)) type:%d\n",
+				addr, addr, addr, expect, type);
+		BUG();
 	}
 
-	if (memcmp(addr, expect, JUMP_LABEL_NOP_SIZE))
-		bug_at(addr, line);
-
 	if (type == JUMP_LABEL_NOP)
 		code = x86_nops[5];