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From: Richard Henderson <richard.henderson@linaro.org>
To: qemu-devel@nongnu.org
Cc: "Luis Pires" <luis.pires@eldorado.org.br>,
	"Alex Bennée" <alex.bennee@linaro.org>
Subject: [PULL 27/34] tcg: Merge buffer protection and guard page protection
Date: Fri, 11 Jun 2021 16:41:37 -0700	[thread overview]
Message-ID: <20210611234144.653682-28-richard.henderson@linaro.org> (raw)
In-Reply-To: <20210611234144.653682-1-richard.henderson@linaro.org>

Do not handle protections on a case-by-case basis in the
various alloc_code_gen_buffer instances; do it within a
single loop in tcg_region_init.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Luis Pires <luis.pires@eldorado.org.br>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tcg/region.c | 45 +++++++++++++++++++++++++++++++--------------
 1 file changed, 31 insertions(+), 14 deletions(-)

diff --git a/tcg/region.c b/tcg/region.c
index e1790ce1e4..294cbd8e65 100644
--- a/tcg/region.c
+++ b/tcg/region.c
@@ -535,11 +535,6 @@ static int alloc_code_gen_buffer(size_t tb_size, int splitwx, Error **errp)
     }
 #endif
 
-    if (qemu_mprotect_rwx(buf, size)) {
-        error_setg_errno(errp, errno, "mprotect of jit buffer");
-        return false;
-    }
-
     region.start_aligned = buf;
     region.total_size = size;
 
@@ -823,8 +818,7 @@ void tcg_region_init(size_t tb_size, int splitwx, unsigned max_cpus)
 {
     const size_t page_size = qemu_real_host_page_size;
     size_t region_size;
-    size_t i;
-    int have_prot;
+    int have_prot, need_prot;
 
     /* Size the buffer.  */
     if (tb_size == 0) {
@@ -884,18 +878,41 @@ void tcg_region_init(size_t tb_size, int splitwx, unsigned max_cpus)
      * 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.
+     * Work with the page protections set up with the initial mapping.
      */
-    for (i = 0; i < region.n; i++) {
+    need_prot = PAGE_READ | PAGE_WRITE;
+#ifndef CONFIG_TCG_INTERPRETER
+    if (tcg_splitwx_diff == 0) {
+        need_prot |= PAGE_EXEC;
+    }
+#endif
+    for (size_t i = 0, n = region.n; i < n; i++) {
         void *start, *end;
 
         tcg_region_bounds(i, &start, &end);
+        if (have_prot != need_prot) {
+            int rc;
 
-        /*
-         * macOS 11.2 has a bug (Apple Feedback FB8994773) in which mprotect
-         * rejects a permission change from RWX -> NONE.  Guard pages are
-         * nice for bug detection but are not essential; ignore any failure.
-         */
-        (void)qemu_mprotect_none(end, page_size);
+            if (need_prot == (PAGE_READ | PAGE_WRITE | PAGE_EXEC)) {
+                rc = qemu_mprotect_rwx(start, end - start);
+            } else if (need_prot == (PAGE_READ | PAGE_WRITE)) {
+                rc = qemu_mprotect_rw(start, end - start);
+            } else {
+                g_assert_not_reached();
+            }
+            if (rc) {
+                error_setg_errno(&error_fatal, errno,
+                                 "mprotect of jit buffer");
+            }
+        }
+        if (have_prot != 0) {
+            /*
+             * macOS 11.2 has a bug (Apple Feedback FB8994773) in which mprotect
+             * rejects a permission change from RWX -> NONE.  Guard pages are
+             * nice for bug detection but are not essential; ignore any failure.
+             */
+            (void)qemu_mprotect_none(end, page_size);
+        }
     }
 
     tcg_region_trees_init();
-- 
2.25.1



  parent reply	other threads:[~2021-06-11 23:59 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-11 23:41 [PULL 00/34] tcg patch queue Richard Henderson
2021-06-11 23:41 ` [PULL 01/34] meson: Split out tcg/meson.build Richard Henderson
2021-06-11 23:41 ` [PULL 02/34] meson: Split out fpu/meson.build Richard Henderson
2021-06-11 23:41 ` [PULL 03/34] tcg: Re-order tcg_region_init vs tcg_prologue_init Richard Henderson
2021-06-14 14:36   ` Christian Borntraeger
2021-06-11 23:41 ` [PULL 04/34] tcg: Remove error return from tcg_region_initial_alloc__locked Richard Henderson
2021-06-11 23:41 ` [PULL 05/34] tcg: Split out tcg_region_initial_alloc Richard Henderson
2021-06-11 23:41 ` [PULL 06/34] tcg: Split out tcg_region_prologue_set Richard Henderson
2021-06-11 23:41 ` [PULL 07/34] tcg: Split out region.c Richard Henderson
2021-06-11 23:41 ` [PULL 08/34] accel/tcg: Inline cpu_gen_init Richard Henderson
2021-06-11 23:41 ` [PULL 09/34] accel/tcg: Move alloc_code_gen_buffer to tcg/region.c Richard Henderson
2021-06-11 23:41 ` [PULL 10/34] accel/tcg: Rename tcg_init to tcg_init_machine Richard Henderson
2021-06-11 23:41 ` [PULL 11/34] tcg: Create tcg_init Richard Henderson
2021-06-11 23:41 ` [PULL 12/34] accel/tcg: Merge tcg_exec_init into tcg_init_machine Richard Henderson
2021-06-11 23:41 ` [PULL 13/34] accel/tcg: Use MiB in tcg_init_machine Richard Henderson
2021-06-11 23:41 ` [PULL 14/34] accel/tcg: Pass down max_cpus to tcg_init Richard Henderson
2021-06-11 23:41 ` [PULL 15/34] tcg: Introduce tcg_max_ctxs Richard Henderson
2021-06-11 23:41 ` [PULL 16/34] tcg: Move MAX_CODE_GEN_BUFFER_SIZE to tcg-target.h Richard Henderson
2021-06-11 23:41 ` [PULL 17/34] tcg: Replace region.end with region.total_size Richard Henderson
2021-06-11 23:41 ` [PULL 18/34] tcg: Rename region.start to region.after_prologue Richard Henderson
2021-06-11 23:41 ` [PULL 19/34] tcg: Tidy tcg_n_regions Richard Henderson
2021-06-11 23:41 ` [PULL 20/34] tcg: Tidy split_cross_256mb Richard Henderson
2021-06-11 23:41 ` [PULL 21/34] tcg: Move in_code_gen_buffer and tests to region.c Richard Henderson
2021-06-11 23:41 ` [PULL 22/34] tcg: Allocate code_gen_buffer into struct tcg_region_state Richard Henderson
2021-06-11 23:41 ` [PULL 23/34] tcg: Return the map protection from alloc_code_gen_buffer Richard Henderson
2021-06-11 23:41 ` [PULL 24/34] tcg: Sink qemu_madvise call to common code Richard Henderson
2021-06-11 23:41 ` [PULL 25/34] util/osdep: Add qemu_mprotect_rw Richard Henderson
2021-06-11 23:41 ` [PULL 26/34] tcg: Round the tb_size default from qemu_get_host_physmem Richard Henderson
2021-06-11 23:41 ` Richard Henderson [this message]
2021-06-11 23:41 ` [PULL 28/34] tcg: When allocating for !splitwx, begin with PROT_NONE Richard Henderson
2021-06-11 23:41 ` [PULL 29/34] tcg: Move tcg_init_ctx and tcg_ctx from accel/tcg/ Richard Henderson
2021-06-11 23:41 ` [PULL 30/34] tcg: Introduce tcg_remove_ops_after Richard Henderson
2021-06-11 23:41 ` [PULL 31/34] tcg: Fix documentation for tcg_constant_* vs tcg_temp_free_* Richard Henderson
2021-06-11 23:41 ` [PULL 32/34] tcg/arm: Fix tcg_out_op function signature Richard Henderson
2021-06-11 23:41 ` [PULL 33/34] softfloat: Fix tp init in float32_exp2 Richard Henderson
2021-06-11 23:41 ` [PULL 34/34] docs/devel: Explain in more detail the TB chaining mechanisms Richard Henderson
2021-06-13 15:13 ` [PULL 00/34] tcg patch queue Peter Maydell
2021-06-13 17:10   ` Peter Maydell
2021-06-14  1:37     ` Richard Henderson
2021-06-14  9:28       ` Peter Maydell
2021-06-14  9:35       ` Alex Bennée
2021-06-14 15:00         ` Philippe Mathieu-Daudé

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