On 23/9/25 11:09, Markus Armbruster wrote:
tcg_region_init() calls one of qemu_mprotect_rwx(),
qemu_mprotect_rw(), and mprotect(), then reports failure with
error_setg_errno(&error_fatal, errno, ...).
The use of &error_fatal is undesirable. qapi/error.h advises:
* Please don't error_setg(&error_fatal, ...), use error_report() and
* exit(), because that's more obvious.
The use of errno is wrong. qemu_mprotect_rwx() and qemu_mprotect_rw()
wrap around qemu_mprotect__osdep(). qemu_mprotect__osdep() calls
mprotect() on POSIX, VirtualProtect() on Windows, and reports failure
with error_report(). VirtualProtect() doesn't set errno. mprotect()
does, but error_report() may clobber it.
Fix tcg_region_init() to report errors only when it calls mprotect(),
and rely on qemu_mprotect_rwx()'s and qemu_mprotect_rw()'s error
reporting otherwise. Use error_report(), not error_setg().
Fixes: 22c6a9938f75 (tcg: Merge buffer protection and guard page protection)
Fixes: 6bc144237a85 (tcg: Use Error with alloc_code_gen_buffer)
Cc: Richard Henderson <[email protected]>
Signed-off-by: Markus Armbruster <[email protected]>
Reviewed-by: Daniel P. Berrangé <[email protected]>
Reviewed-by: Richard Henderson <[email protected]>
---
tcg/region.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/tcg/region.c b/tcg/region.c
index 7ea0b37a84..2181267e48 100644
--- a/tcg/region.c
+++ b/tcg/region.c
@@ -832,13 +832,16 @@ void tcg_region_init(size_t tb_size, int splitwx,
unsigned max_threads)
} else {
#ifdef CONFIG_POSIX
rc = mprotect(start, end - start, need_prot);
+ if (rc) {
+ error_report("mprotect of jit buffer: %s",
+ strerror(errno));
I'm not keen on handling errors differently in the same function.
qemu_mprotect_rwx() and qemu_mprotect_rw() already print the error.
Why not add qemu_mprotect() as a simple qemu_mprotect__osdep() alias,
then call it here, also covering the non-POSIX case?
(Question for Richard, after looking at commits 22c6a9938f7 and more
importantly 97a83753c9 -- wondering about WoA).
+ }
#else
g_assert_not_reached();
#endif
}
if (rc) {
- error_setg_errno(&error_fatal, errno,
- "mprotect of jit buffer");
+ exit(1);
}> }
if (have_prot != 0) {
