x86/alternatives: Introduce 'struct smp_text_poke_array' and move tp_vec and tp_vec_n...

struct text_poke_array is an equivalent structure to these global variables:

	static struct smp_text_poke_loc tp_vec[TP_VEC_MAX];
	static int tp_vec_nr;

Note that we intentionally mirror much of the naming of
'struct text_poke_int3_vec', which will further highlight
the unecessary layering going on in this code, and will
ease its removal.

No change in functionality.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250411054105.2341982-28-mingo@kernel.org

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 4fa26a4351a640cca89fcace087c0f59d5de3574..0af2203944800147a3372517994b711813e77166 100644 (file)
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -2467,14 +2467,21 @@ struct smp_text_poke_loc {
 };
 
 struct text_poke_int3_vec {
-       struct smp_text_poke_loc *vec;
        int nr_entries;
+       struct smp_text_poke_loc *vec;
 };
 
 static DEFINE_PER_CPU(atomic_t, text_poke_array_refs);
 
 static struct text_poke_int3_vec int3_vec;
 
+#define TP_ARRAY_NR_ENTRIES_MAX (PAGE_SIZE / sizeof(struct smp_text_poke_loc))
+
+static struct smp_text_poke_array {
+       int nr_entries;
+       struct smp_text_poke_loc vec[TP_ARRAY_NR_ENTRIES_MAX];
+} text_poke_array;
+
 static __always_inline
 struct text_poke_int3_vec *try_get_desc(void)
 {
@@ -2510,10 +2517,6 @@ 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;
@@ -2538,7 +2541,7 @@ noinstr int smp_text_poke_int3_handler(struct pt_regs *regs)
        if (!desc)
                return 0;
 
-       WARN_ON_ONCE(desc->vec != tp_vec);
+       WARN_ON_ONCE(desc->vec != text_poke_array.vec);
 
        /*
         * Discount the INT3. See smp_text_poke_batch_process().
@@ -2627,8 +2630,8 @@ static void smp_text_poke_batch_process(struct smp_text_poke_loc *tp, unsigned i
 
        lockdep_assert_held(&text_mutex);
 
-       WARN_ON_ONCE(tp != tp_vec);
-       WARN_ON_ONCE(nr_entries != tp_vec_nr);
+       WARN_ON_ONCE(tp != text_poke_array.vec);
+       WARN_ON_ONCE(nr_entries != text_poke_array.nr_entries);
 
        int3_vec.vec = tp;
        int3_vec.nr_entries = nr_entries;
@@ -2843,7 +2846,7 @@ static void text_poke_int3_loc_init(struct smp_text_poke_loc *tp, void *addr,
 }
 
 /*
- * We hard rely on the tp_vec being ordered; ensure this is so by flushing
+ * We hard rely on the text_poke_array.vec being ordered; ensure this is so by flushing
  * early if needed.
  */
 static bool text_poke_addr_ordered(void *addr)
@@ -2852,7 +2855,7 @@ static bool text_poke_addr_ordered(void *addr)
 
        WARN_ON_ONCE(!addr);
 
-       if (!tp_vec_nr)
+       if (!text_poke_array.nr_entries)
                return true;
 
        /*
@@ -2861,7 +2864,7 @@ static bool text_poke_addr_ordered(void *addr)
         * is violated and we must first flush all pending patching
         * requests:
         */
-       tp = &tp_vec[tp_vec_nr-1];
+       tp = &text_poke_array.vec[text_poke_array.nr_entries-1];
        if ((unsigned long)text_poke_addr(tp) > (unsigned long)addr)
                return false;
 
@@ -2870,9 +2873,9 @@ static bool text_poke_addr_ordered(void *addr)
 
 void smp_text_poke_batch_finish(void)
 {
-       if (tp_vec_nr) {
-               smp_text_poke_batch_process(tp_vec, tp_vec_nr);
-               tp_vec_nr = 0;
+       if (text_poke_array.nr_entries) {
+               smp_text_poke_batch_process(text_poke_array.vec, text_poke_array.nr_entries);
+               text_poke_array.nr_entries = 0;
        }
 }
 
@@ -2880,9 +2883,9 @@ static void smp_text_poke_batch_flush(void *addr)
 {
        lockdep_assert_held(&text_mutex);
 
-       if (tp_vec_nr == TP_VEC_MAX || !text_poke_addr_ordered(addr)) {
-               smp_text_poke_batch_process(tp_vec, tp_vec_nr);
-               tp_vec_nr = 0;
+       if (text_poke_array.nr_entries == TP_ARRAY_NR_ENTRIES_MAX || !text_poke_addr_ordered(addr)) {
+               smp_text_poke_batch_process(text_poke_array.vec, text_poke_array.nr_entries);
+               text_poke_array.nr_entries = 0;
        }
 }
 
@@ -2892,7 +2895,7 @@ void __ref smp_text_poke_batch_add(void *addr, const void *opcode, size_t len, c
 
        smp_text_poke_batch_flush(addr);
 
-       tp = &tp_vec[tp_vec_nr++];
+       tp = &text_poke_array.vec[text_poke_array.nr_entries++];
        text_poke_int3_loc_init(tp, addr, opcode, len, emulate);
 }
 
@@ -2912,9 +2915,9 @@ void __ref smp_text_poke_single(void *addr, const void *opcode, size_t len, cons
        struct smp_text_poke_loc *tp;
 
        /* Batch-patching should not be mixed with single-patching: */
-       WARN_ON_ONCE(tp_vec_nr != 0);
+       WARN_ON_ONCE(text_poke_array.nr_entries != 0);
 
-       tp = &tp_vec[tp_vec_nr++];
+       tp = &text_poke_array.vec[text_poke_array.nr_entries++];
        text_poke_int3_loc_init(tp, addr, opcode, len, emulate);
 
        smp_text_poke_batch_finish();