From 8269c01417a3e0bdb444b1bdac1d9b6c8bc9e667 Mon Sep 17 00:00:00 2001
From: Richard Henderson <richard.henderson@linaro.org>
Date: Tue, 4 Oct 2022 15:40:22 -0700
Subject: [PATCH] accel/tcg: Simplify page_get/alloc_target_data
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Since the only user, Arm MTE, always requires allocation,
merge the get and alloc functions to always produce a
non-null result.  Also assume that the user has already
checked page validity.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 accel/tcg/user-exec.c   | 16 ++++------------
 include/exec/cpu-all.h  | 21 ++++++---------------
 target/arm/mte_helper.c |  4 ----
 3 files changed, 10 insertions(+), 31 deletions(-)

diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
index 927b91900fd..fb7d6ee9e96 100644
--- a/accel/tcg/user-exec.c
+++ b/accel/tcg/user-exec.c
@@ -242,19 +242,11 @@ void page_reset_target_data(target_ulong start, target_ulong end)
 void *page_get_target_data(target_ulong address)
 {
     PageDesc *p = page_find(address >> TARGET_PAGE_BITS);
-    return p ? p->target_data : NULL;
-}
+    void *ret = p->target_data;
 
-void *page_alloc_target_data(target_ulong address)
-{
-    PageDesc *p = page_find(address >> TARGET_PAGE_BITS);
-    void *ret = NULL;
-
-    if (p->flags & PAGE_VALID) {
-        ret = p->target_data;
-        if (!ret) {
-            p->target_data = ret = g_malloc0(TARGET_PAGE_DATA_SIZE);
-        }
+    if (!ret) {
+        ret = g_malloc0(TARGET_PAGE_DATA_SIZE);
+        p->target_data = ret;
     }
     return ret;
 }
diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h
index 854adc4ac29..2eb11765380 100644
--- a/include/exec/cpu-all.h
+++ b/include/exec/cpu-all.h
@@ -281,27 +281,18 @@ void page_reset_target_data(target_ulong start, target_ulong end);
 int page_check_range(target_ulong start, target_ulong len, int flags);
 
 /**
- * page_alloc_target_data(address)
+ * page_get_target_data(address)
  * @address: guest virtual address
  *
- * Allocate TARGET_PAGE_DATA_SIZE bytes of out-of-band data to associate
- * with the guest page at @address.  If the page is not mapped, NULL will
- * be returned.  If there is existing data associated with @address,
- * no new memory will be allocated.
+ * Return TARGET_PAGE_DATA_SIZE bytes of out-of-band data to associate
+ * with the guest page at @address, allocating it if necessary.  The
+ * caller should already have verified that the address is valid.
  *
  * The memory will be freed when the guest page is deallocated,
  * e.g. with the munmap system call.
  */
-void *page_alloc_target_data(target_ulong address);
-
-/**
- * page_get_target_data(address)
- * @address: guest virtual address
- *
- * Return any out-of-bound memory assocated with the guest page
- * at @address, as per page_alloc_target_data.
- */
-void *page_get_target_data(target_ulong address);
+void *page_get_target_data(target_ulong address)
+    __attribute__((returns_nonnull));
 #endif
 
 CPUArchState *cpu_copy(CPUArchState *env);
diff --git a/target/arm/mte_helper.c b/target/arm/mte_helper.c
index a9c5fc2cb21..86b37548386 100644
--- a/target/arm/mte_helper.c
+++ b/target/arm/mte_helper.c
@@ -95,10 +95,6 @@ static uint8_t *allocation_tag_mem(CPUARMState *env, int ptr_mmu_idx,
     }
 
     tags = page_get_target_data(clean_ptr);
-    if (tags == NULL) {
-        tags = page_alloc_target_data(clean_ptr);
-        assert(tags != NULL);
-    }
 
     index = extract32(ptr, LOG2_TAG_GRANULE + 1,
                       TARGET_PAGE_BITS - LOG2_TAG_GRANULE - 1);