diff mbox series

[PATCH-for-10.1,1/2] tcg: Introduce and use target_has_precise_smc() runtime helper

Message ID 20250404235624.67816-2-philmd@linaro.org
State New
Headers show
Series tcg: Convert TARGET_HAS_PRECISE_SMC to TCGCPUOps::has_precise_smc field | expand

Commit Message

Philippe Mathieu-Daudé April 4, 2025, 11:56 p.m. UTC 
target_has_precise_smc() returns the value of the
TARGET_HAS_PRECISE_SMC definition at runtime.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 accel/tcg/tb-internal.h |  3 +++
 accel/tcg/cpu-exec.c    |  9 +++++++++
 accel/tcg/tb-maint.c    | 18 +++++-------------
 accel/tcg/user-exec.c   | 10 +++++-----
 4 files changed, 22 insertions(+), 18 deletions(-)

Comments

Richard Henderson April 5, 2025, 3:57 p.m. UTC | #1 
On 4/4/25 16:56, Philippe Mathieu-Daudé wrote:
> diff --git a/accel/tcg/tb-maint.c b/accel/tcg/tb-maint.c
> index d479f53ae02..ae12ad2d867 100644
> --- a/accel/tcg/tb-maint.c
> +++ b/accel/tcg/tb-maint.c
> @@ -1057,10 +1057,7 @@ bool tb_invalidate_phys_page_unwind(tb_page_addr_t addr, uintptr_t pc)
>        * Without precise smc semantics, or when outside of a TB,
>        * we can skip to invalidate.
>        */
> -#ifndef TARGET_HAS_PRECISE_SMC
> -    pc = 0;
> -#endif
> -    if (!pc) {
> +    if (!target_has_precise_smc() || !pc) {
>           tb_invalidate_phys_page(addr);
>           return false;
>       }

For the record, in my v2 I reverse these tests, since !pc is simpler.

> @@ -1109,10 +1106,9 @@ tb_invalidate_phys_page_range__locked(struct page_collection *pages,
>   {
>       TranslationBlock *tb;
>       PageForEachNext n;
> -#ifdef TARGET_HAS_PRECISE_SMC
>       bool current_tb_modified = false;
> -    TranslationBlock *current_tb = retaddr ? tcg_tb_lookup(retaddr) : NULL;
> -#endif /* TARGET_HAS_PRECISE_SMC */
> +    TranslationBlock *current_tb = (target_has_precise_smc() && retaddr)
> +                                   ? tcg_tb_lookup(retaddr) : NULL;
>   
>       /* Range may not cross a page. */
>       tcg_debug_assert(((start ^ last) & TARGET_PAGE_MASK) == 0);
> @@ -1134,8 +1130,7 @@ tb_invalidate_phys_page_range__locked(struct page_collection *pages,
>               tb_last = tb_start + (tb_last & ~TARGET_PAGE_MASK);
>           }
>           if (!(tb_last < start || tb_start > last)) {
> -#ifdef TARGET_HAS_PRECISE_SMC
> -            if (current_tb == tb &&
> +            if (target_has_precise_smc() && current_tb == tb &&
>                   (tb_cflags(current_tb) & CF_COUNT_MASK) != 1) {

For the record, we can eliminate the target_has_precise_smc() test here, because we've set 
current_tb == NULL, and thus the current_tb == tb test always fails ...

> @@ -1157,15 +1151,13 @@ tb_invalidate_phys_page_range__locked(struct page_collection *pages,
>           tlb_unprotect_code(start);
>       }
>   
> -#ifdef TARGET_HAS_PRECISE_SMC
> -    if (current_tb_modified) {
> +    if (target_has_precise_smc() && current_tb_modified) {

... which in turn means that current_tb_modified is never set.

Thus only the one runtime test at the top of the function suffices.


r~
diff mbox series

Patch

diff --git a/accel/tcg/tb-internal.h b/accel/tcg/tb-internal.h
index 08538e2896b..a844709bbb2 100644
--- a/accel/tcg/tb-internal.h
+++ b/accel/tcg/tb-internal.h
@@ -44,6 +44,9 @@  void tb_unlock_page1(tb_page_addr_t, tb_page_addr_t);
 void tb_unlock_pages(TranslationBlock *);
 #endif
 
+/* Whether the target supports implicit self modifying code */
+bool target_has_precise_smc(void);
+
 #ifdef CONFIG_SOFTMMU
 void tb_invalidate_phys_range_fast(ram_addr_t ram_addr,
                                    unsigned size,
diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
index b00f046b29f..cfe3b93e1e3 100644
--- a/accel/tcg/cpu-exec.c
+++ b/accel/tcg/cpu-exec.c
@@ -1065,6 +1065,15 @@  int cpu_exec(CPUState *cpu)
     return ret;
 }
 
+bool target_has_precise_smc(void)
+{
+#ifdef TARGET_HAS_PRECISE_SMC
+    return true;
+#else
+    return false;
+#endif
+}
+
 bool tcg_exec_realizefn(CPUState *cpu, Error **errp)
 {
     static bool tcg_target_initialized;
diff --git a/accel/tcg/tb-maint.c b/accel/tcg/tb-maint.c
index d479f53ae02..ae12ad2d867 100644
--- a/accel/tcg/tb-maint.c
+++ b/accel/tcg/tb-maint.c
@@ -1057,10 +1057,7 @@  bool tb_invalidate_phys_page_unwind(tb_page_addr_t addr, uintptr_t pc)
      * Without precise smc semantics, or when outside of a TB,
      * we can skip to invalidate.
      */
-#ifndef TARGET_HAS_PRECISE_SMC
-    pc = 0;
-#endif
-    if (!pc) {
+    if (!target_has_precise_smc() || !pc) {
         tb_invalidate_phys_page(addr);
         return false;
     }
@@ -1109,10 +1106,9 @@  tb_invalidate_phys_page_range__locked(struct page_collection *pages,
 {
     TranslationBlock *tb;
     PageForEachNext n;
-#ifdef TARGET_HAS_PRECISE_SMC
     bool current_tb_modified = false;
-    TranslationBlock *current_tb = retaddr ? tcg_tb_lookup(retaddr) : NULL;
-#endif /* TARGET_HAS_PRECISE_SMC */
+    TranslationBlock *current_tb = (target_has_precise_smc() && retaddr)
+                                   ? tcg_tb_lookup(retaddr) : NULL;
 
     /* Range may not cross a page. */
     tcg_debug_assert(((start ^ last) & TARGET_PAGE_MASK) == 0);
@@ -1134,8 +1130,7 @@  tb_invalidate_phys_page_range__locked(struct page_collection *pages,
             tb_last = tb_start + (tb_last & ~TARGET_PAGE_MASK);
         }
         if (!(tb_last < start || tb_start > last)) {
-#ifdef TARGET_HAS_PRECISE_SMC
-            if (current_tb == tb &&
+            if (target_has_precise_smc() && current_tb == tb &&
                 (tb_cflags(current_tb) & CF_COUNT_MASK) != 1) {
                 /*
                  * If we are modifying the current TB, we must stop
@@ -1147,7 +1142,6 @@  tb_invalidate_phys_page_range__locked(struct page_collection *pages,
                 current_tb_modified = true;
                 cpu_restore_state_from_tb(current_cpu, current_tb, retaddr);
             }
-#endif /* TARGET_HAS_PRECISE_SMC */
             tb_phys_invalidate__locked(tb);
         }
     }
@@ -1157,15 +1151,13 @@  tb_invalidate_phys_page_range__locked(struct page_collection *pages,
         tlb_unprotect_code(start);
     }
 
-#ifdef TARGET_HAS_PRECISE_SMC
-    if (current_tb_modified) {
+    if (target_has_precise_smc() && current_tb_modified) {
         page_collection_unlock(pages);
         /* Force execution of one insn next time.  */
         current_cpu->cflags_next_tb = 1 | CF_NOIRQ | curr_cflags(current_cpu);
         mmap_unlock();
         cpu_loop_exit_noexc(current_cpu);
     }
-#endif
 }
 
 /*
diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
index 5eef8e7f186..135c54980a2 100644
--- a/accel/tcg/user-exec.c
+++ b/accel/tcg/user-exec.c
@@ -731,12 +731,12 @@  int page_unprotect(tb_page_addr_t address, uintptr_t pc)
          * this thread raced with another one which got here first and
          * set the page to PAGE_WRITE and did the TB invalidate for us.
          */
-#ifdef TARGET_HAS_PRECISE_SMC
-        TranslationBlock *current_tb = tcg_tb_lookup(pc);
-        if (current_tb) {
-            current_tb_invalidated = tb_cflags(current_tb) & CF_INVALID;
+        if (target_has_precise_smc()) {
+            TranslationBlock *current_tb = tcg_tb_lookup(pc);
+            if (current_tb) {
+                current_tb_invalidated = tb_cflags(current_tb) & CF_INVALID;
+            }
         }
-#endif
     } else {
         int host_page_size = qemu_real_host_page_size();
         target_ulong start, len, i;