[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[PULL 1/5] tcg: Do not set guard pages on the rx portion of code_gen_buf
From: |
Richard Henderson |
Subject: |
[PULL 1/5] tcg: Do not set guard pages on the rx portion of code_gen_buffer |
Date: |
Tue, 23 Mar 2021 19:43:28 -0600 |
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(-)
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();
--
2.25.1
- [PULL 0/5] tcg patch queue for 6.0, Richard Henderson, 2021/03/23
- [PULL 3/5] exec: Rename exec-vary.c as page-vary.c, Richard Henderson, 2021/03/23
- [PULL 4/5] exec: Extract 'page-vary.h' header, Richard Henderson, 2021/03/23
- [PULL 5/5] exec: Build page-vary-common.c with -fno-lto, Richard Henderson, 2021/03/23
- [PULL 1/5] tcg: Do not set guard pages on the rx portion of code_gen_buffer,
Richard Henderson <=
- [PULL 2/5] tcg: Workaround macOS 11.2 mprotect bug, Richard Henderson, 2021/03/23
- Re: [PULL 0/5] tcg patch queue for 6.0, Peter Maydell, 2021/03/24