(Cc'ing Joelle)
On 16/8/23 16:25, Richard Henderson wrote:
For linux aarch64 host supporting BTI, map the buffer
to require BTI instructions at branch landing pads.
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
tcg/region.c | 39 ++++++++++++++++++++++++++++-----------
1 file changed, 28 insertions(+), 11 deletions(-)
diff --git a/tcg/region.c b/tcg/region.c
index 2b28ed3556..58cb68c6c8 100644
--- a/tcg/region.c
+++ b/tcg/region.c
@@ -33,8 +33,19 @@
#include "tcg/tcg.h"
#include "exec/translation-block.h"
#include "tcg-internal.h"
+#include "host/cpuinfo.h"
+/*
+ * Local source-level compatibility with Unix.
+ * Used by tcg_region_init below.
+ */
+#if defined(_WIN32)
+#define PROT_READ 1
+#define PROT_WRITE 2
+#define PROT_EXEC 4
+#endif
+
struct tcg_region_tree {
QemuMutex lock;
QTree *tree;
@@ -83,6 +94,16 @@ bool in_code_gen_buffer(const void *p)
return (size_t)(p - region.start_aligned) <= region.total_size;
}
+static int host_prot_read_exec(void)
+{
+#if defined(CONFIG_LINUX) && defined(HOST_AARCH64) && defined(PROT_BTI)
+ if (cpuinfo & CPUINFO_BTI) {
+ return PROT_READ | PROT_EXEC | PROT_BTI;
+ }
+#endif
+ return PROT_READ | PROT_EXEC;
+}
+
#ifdef CONFIG_DEBUG_TCG
const void *tcg_splitwx_to_rx(void *rw)
{
@@ -505,14 +526,6 @@ static int alloc_code_gen_buffer(size_t tb_size, int
splitwx, Error **errp)
return PROT_READ | PROT_WRITE;
}
#elif defined(_WIN32)
-/*
- * Local source-level compatibility with Unix.
- * Used by tcg_region_init below.
- */
-#define PROT_READ 1
-#define PROT_WRITE 2
-#define PROT_EXEC 4
-
static int alloc_code_gen_buffer(size_t size, int splitwx, Error **errp)
{
void *buf;
@@ -567,7 +580,7 @@ static int alloc_code_gen_buffer_splitwx_memfd(size_t size,
Error **errp)
goto fail;
}
- buf_rx = mmap(NULL, size, PROT_READ | PROT_EXEC, MAP_SHARED, fd, 0);
+ buf_rx = mmap(NULL, size, host_prot_read_exec(), MAP_SHARED, fd, 0);
if (buf_rx == MAP_FAILED) {
goto fail_rx;
}
@@ -642,7 +655,7 @@ static int alloc_code_gen_buffer_splitwx_vmremap(size_t
size, Error **errp)
return -1;
}
- if (mprotect((void *)buf_rx, size, PROT_READ | PROT_EXEC) != 0) {
+ if (mprotect((void *)buf_rx, size, host_prot_read_exec()) != 0) {
error_setg_errno(errp, errno, "mprotect for jit splitwx");
munmap((void *)buf_rx, size);
munmap((void *)buf_rw, size);
@@ -805,7 +818,7 @@ void tcg_region_init(size_t tb_size, int splitwx, unsigned
max_cpus)
need_prot = PROT_READ | PROT_WRITE;
#ifndef CONFIG_TCG_INTERPRETER
if (tcg_splitwx_diff == 0) {
- need_prot |= PROT_EXEC;
+ need_prot |= host_prot_read_exec();
}
#endif
for (size_t i = 0, n = region.n; i < n; i++) {
@@ -820,7 +833,11 @@ void tcg_region_init(size_t tb_size, int splitwx, unsigned
max_cpus)
} else if (need_prot == (PROT_READ | PROT_WRITE)) {
rc = qemu_mprotect_rw(start, end - start);
} else {
+#ifdef CONFIG_POSIX
+ rc = mprotect(start, end - start, need_prot);
Hmm this bypass the qemu_real_host_page_mask() checks in
qemu_mprotect__osdep(), but I guess this is acceptable.
Reviewed-by: Philippe Mathieu-Daudé <phi...@linaro.org>
+#else
g_assert_not_reached();
+#endif
}
if (rc) {
error_setg_errno(&error_fatal, errno,
