diff mbox series

[PULL,1/5] tcg: Do not set guard pages on the rx portion of code_gen_buffer

Message ID 20210324014332.6331-2-richard.henderson@linaro.org
State Accepted
Commit 15c4e8fe44e34eee4a13135eeb121b3b26e4cd1b
Headers show
Series tcg patch queue for 6.0 | expand

Commit Message

Richard Henderson March 24, 2021, 1:43 a.m. UTC 
The rw portion of the buffer is the only one in which overruns
can be generated.  Allow the rx portion to be more completely
covered by huge pages.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Tested-by: Roman Bolshakov <r.bolshakov@yadro.com>

Reviewed-by: Roman Bolshakov <r.bolshakov@yadro.com>

Message-Id: <20210320165720.1813545-2-richard.henderson@linaro.org>
---
 tcg/tcg.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

-- 
2.25.1
diff mbox series

Patch

diff --git a/tcg/tcg.c b/tcg/tcg.c
index de91bb6e9e..88c9e6f8a4 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -828,7 +828,6 @@  void tcg_region_init(void)
     size_t region_size;
     size_t n_regions;
     size_t i;
-    uintptr_t splitwx_diff;
 
     n_regions = tcg_n_regions();
 
@@ -858,8 +857,11 @@  void tcg_region_init(void)
     /* account for that last guard page */
     region.end -= page_size;
 
-    /* set guard pages */
-    splitwx_diff = tcg_splitwx_diff;
+    /*
+     * Set guard pages in the rw buffer, as that's the one into which
+     * buffer overruns could occur.  Do not set guard pages in the rx
+     * buffer -- let that one use hugepages throughout.
+     */
     for (i = 0; i < region.n; i++) {
         void *start, *end;
         int rc;
@@ -867,10 +869,6 @@  void tcg_region_init(void)
         tcg_region_bounds(i, &start, &end);
         rc = qemu_mprotect_none(end, page_size);
         g_assert(!rc);
-        if (splitwx_diff) {
-            rc = qemu_mprotect_none(end + splitwx_diff, page_size);
-            g_assert(!rc);
-        }
     }
 
     tcg_region_trees_init();