linux-kernel - [PATCH 27/41] x86/alternatives: Remove the tp

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Message-ID: <20250327205355.378659-28-mingo@kernel.org>
Date: Thu, 27 Mar 2025 21:53:40 +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 27/41] x86/alternatives: Remove the tp_vec indirection

At this point we are always working out of an uptodate
tp_array, there's no need for text_poke_int3_handler()
to read via the int3_vec indirection - remove it.

This simplifies the code:

   1 file changed, 5 insertions(+), 15 deletions(-)

Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/alternative.c | 24 +++++++-----------------
 1 file changed, 7 insertions(+), 17 deletions(-)

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index cf3bcaa97957..3baef1827f3c 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -2466,15 +2466,6 @@ struct text_poke_int3_loc {
 	u8 old;
 };
 
-struct text_poke_int3_vec {
-	int nr_entries;
-	struct text_poke_int3_loc *vec;
-};
-
-static DEFINE_PER_CPU(atomic_t, int3_refs);
-
-static struct text_poke_int3_vec int3_vec;
-
 #define TP_ARRAY_NR_ENTRIES_MAX (PAGE_SIZE / sizeof(struct text_poke_int3_loc))
 
 static struct text_poke_int3_array {
@@ -2482,15 +2473,17 @@ static struct text_poke_int3_array {
 	struct text_poke_int3_loc vec[TP_ARRAY_NR_ENTRIES_MAX];
 } tp_array;
 
+static DEFINE_PER_CPU(atomic_t, int3_refs);
+
 static __always_inline
-struct text_poke_int3_vec *try_get_desc(void)
+struct text_poke_int3_array *try_get_desc(void)
 {
 	atomic_t *refs = this_cpu_ptr(&int3_refs);
 
 	if (!raw_atomic_inc_not_zero(refs))
 		return NULL;
 
-	return &int3_vec;
+	return &tp_array;
 }
 
 static __always_inline void put_desc(void)
@@ -2519,7 +2512,7 @@ static __always_inline int patch_cmp(const void *key, const void *elt)
 
 noinstr int text_poke_int3_handler(struct pt_regs *regs)
 {
-	struct text_poke_int3_vec *desc;
+	struct text_poke_int3_array *desc;
 	struct text_poke_int3_loc *tp;
 	int ret = 0;
 	void *ip;
@@ -2529,7 +2522,7 @@ noinstr int text_poke_int3_handler(struct pt_regs *regs)
 
 	/*
 	 * Having observed our INT3 instruction, we now must observe
-	 * int3_vec with non-zero refcount:
+	 * tp_array with non-zero refcount:
 	 *
 	 *	int3_refs = 1		INT3
 	 *	WMB			RMB
@@ -2633,12 +2626,9 @@ static void text_poke_int3_batch(struct text_poke_int3_loc *tp, unsigned int nr_
 	WARN_ON_ONCE(tp != tp_array.vec);
 	WARN_ON_ONCE(nr_entries != tp_array.nr_entries);
 
-	int3_vec.vec = tp;
-	int3_vec.nr_entries = nr_entries;
-
 	/*
 	 * Corresponds to the implicit memory barrier in try_get_desc() to
-	 * ensure reading a non-zero refcount provides up to date int3_vec data.
+	 * ensure reading a non-zero refcount provides up to date tp_array data.
 	 */
 	for_each_possible_cpu(i)
 		atomic_set_release(per_cpu_ptr(&int3_refs, i), 1);
-- 
2.45.2