[tip: x86/alternatives] x86/alternatives: Assert that smp_text_poke_int3_handler() can only ever handle 'tp_vec[]' based requests

[tip-bot2 for Ingo Molnar]

The following commit has been merged into the x86/alternatives branch of tip:

Commit-ID:     476ad071c678d70623cdb14fadd21818f64cc45b
Gitweb:        https://git.kernel.org/tip/476ad071c678d70623cdb14fadd21818f64cc45b
Author:        Ingo Molnar <mingo@xxxxxxxxxx>
AuthorDate:    Fri, 11 Apr 2025 07:40:37 +02:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Fri, 11 Apr 2025 11:01:34 +02:00

x86/alternatives: Assert that smp_text_poke_int3_handler() can only ever handle 'tp_vec[]' based requests

Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: "H . Peter Anvin" <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20250411054105.2341982-26-mingo@xxxxxxxxxx
---
 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 b4cb867..329f6ee 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 smp_text_poke_loc))
+static struct smp_text_poke_loc tp_vec[TP_VEC_MAX];
+static int tp_vec_nr;
+
 noinstr int smp_text_poke_int3_handler(struct pt_regs *regs)
 {
 	struct text_poke_int3_vec *desc;
@@ -2534,6 +2538,8 @@ noinstr int smp_text_poke_int3_handler(struct pt_regs *regs)
 	if (!desc)
 		return 0;
 
+	WARN_ON_ONCE(desc->vec != tp_vec);
+
 	/*
 	 * Discount the INT3. See smp_text_poke_batch_process().
 	 */
@@ -2592,10 +2598,6 @@ out_put:
 	return ret;
 }
 
-#define TP_VEC_MAX (PAGE_SIZE / sizeof(struct smp_text_poke_loc))
-static struct smp_text_poke_loc tp_vec[TP_VEC_MAX];
-static int tp_vec_nr;
-
 /**
  * smp_text_poke_batch_process() -- update instructions on live kernel on SMP
  * @tp:			vector of instructions to patch