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authorPeter Maydell <peter.maydell@linaro.org>2018-04-12 15:02:22 +0100
committerPeter Maydell <peter.maydell@linaro.org>2018-04-16 11:52:33 +0100
commitaac8f55633f4470e2cb0952bf1a6be3e57d16211 (patch)
tree09027284894543af949f9c6abdeeb31270475578
parent161dfd1e7fad1203840c0390f235030eba3fd23c (diff)
downloadqemu-arm-aac8f55633f4470e2cb0952bf1a6be3e57d16211.tar.gz
linux-user/signal.c: Put AArch64 frame record in the right place
AArch64 stack frames include a 'frame record' which holds a pointer to the next frame record in the chain and the LR on entry to the function. The procedure calling standard doesn't mandate where exactly this frame record is in the stack frame, but for signal frames the kernel puts it right at the top. We used to put it there too, but in commit 7f0f4208b3a96f22 we accidentally put the "enlarge to the 4K reserved space minimum" check after the "allow for the frame record" code, rather than before it, with the effect that the frame record would be inside the reserved space and immediately after the last used part of it. Move the frame record back out of the reserved space to where we used to put it. This bug shouldn't break any sensible guest code, but test programs that deliberately look at the internal details of the signal frame layout will not find what they are expecting to see. Fixes: 7f0f4208b3a96f22 Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Laurent Vivier <laurent@vivier.eu> Message-id: 20180412140222.2096-1-peter.maydell@linaro.org
-rw-r--r--linux-user/signal.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/linux-user/signal.c b/linux-user/signal.c
index 8d9e6e8410..e6dfe0adfd 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -1843,6 +1843,12 @@ static void target_setup_frame(int usig, struct target_sigaction *ka,
layout.total_size += sizeof(struct target_aarch64_ctx);
}
+ /* We must always provide at least the standard 4K reserved space,
+ * even if we don't use all of it (this is part of the ABI)
+ */
+ layout.total_size = MAX(layout.total_size,
+ sizeof(struct target_rt_sigframe));
+
/* Reserve space for the return code. On a real system this would
* be within the VDSO. So, despite the name this is not a "real"
* record within the frame.
@@ -1850,12 +1856,6 @@ static void target_setup_frame(int usig, struct target_sigaction *ka,
fr_ofs = layout.total_size;
layout.total_size += sizeof(struct target_rt_frame_record);
- /* We must always provide at least the standard 4K reserved space,
- * even if we don't use all of it (this is part of the ABI)
- */
- layout.total_size = MAX(layout.total_size,
- sizeof(struct target_rt_sigframe));
-
frame_addr = get_sigframe(ka, env, layout.total_size);
trace_user_setup_frame(env, frame_addr);
if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {