linux-kernel - [PATCH 21/41] x86/alternatives: Assert that text_poke_int3_handler() can only ever handle 'tp

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Message-ID: <20250327205355.378659-22-mingo@kernel.org>
Date: Thu, 27 Mar 2025 21:53:34 +0100
From: Ingo Molnar <mingo@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Juergen Gross <jgross@...e.com>,
	"H . Peter Anvin" <hpa@...or.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Borislav Petkov <bp@...en8.de>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 21/41] x86/alternatives: Assert that text_poke_int3_handler() can only ever handle 'tp_vec[]' based requests

Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/alternative.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index f75806d699be..883c2146ce54 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -2510,6 +2510,10 @@ static __always_inline int patch_cmp(const void *key, const void *elt)
 	return 0;
 }
 
+#define TP_VEC_MAX (PAGE_SIZE / sizeof(struct text_poke_int3_loc))
+static struct text_poke_int3_loc tp_vec[TP_VEC_MAX];
+static int tp_vec_nr;
+
 noinstr int text_poke_int3_handler(struct pt_regs *regs)
 {
 	struct text_poke_int3_vec *desc;
@@ -2534,6 +2538,8 @@ noinstr int text_poke_int3_handler(struct pt_regs *regs)
 	if (!desc)
 		return 0;
 
+	WARN_ON_ONCE(desc->vec != tp_vec);
+
 	/*
 	 * Discount the INT3. See text_poke_int3_batch().
 	 */
@@ -2592,10 +2598,6 @@ noinstr int text_poke_int3_handler(struct pt_regs *regs)
 	return ret;
 }
 
-#define TP_VEC_MAX (PAGE_SIZE / sizeof(struct text_poke_int3_loc))
-static struct text_poke_int3_loc tp_vec[TP_VEC_MAX];
-static int tp_vec_nr;
-
 /**
  * text_poke_int3_batch() -- update instructions on live kernel on SMP
  * @tp:			vector of instructions to patch
-- 
2.45.2