qemu/linux-user
Mukilan Thiyagarajan c979d901c8 linux-user/hexagon: fix signal context save & restore
This patch fixes the issue originally reported in
this thread:

https://lists.gnu.org/archive/html/qemu-devel/2021-11/msg01102.html

The root cause of the issue is a bug in the hexagon specific
logic for saving & restoring context during signal delivery.
The CPU state has two different representations for the
predicate registers. The current logic saves & restores only
the aliased HEX_REG_P3_O register, which is part of env->gpr[]
field in the CPU state, but not the individual byte-level
predicate registers (pO, p1, p2, p3) backed by env->pred[].

Since all predicated instructions refer only to the
indiviual registers, switching to and back from a signal handler
can clobber these registers if the signal handler writes to them
causing the normal application code to behave unpredictably when
context is restored.

In the reported issue with the 'signals' test, since the updated
hexagon toolchain had built musl with -O2, the functions called
from non_trivial_free were inlined. This meant that the code
emitted reused predicate P0 computed in the entry translation
block of the function non_trivial_free in one of the child TB
as part of an assertion. Since P0 is clobbered by the signal
handler in the signals test, the assertion in non_trivial_free
fails incorectly. Since musl for hexagon implements the 'abort'
function by deliberately writing to memory via null pointer,
this causes the test to fail with segmentation fault.

This patch modifies the signal context save & restore logic
to include the individual p0, p1, p2, p3 and excludes the
32b p3_0 register since its value is derived from the former
registers. It also adds a new test case that reliabily
reproduces the issue for all four predicate registers.

Buglink: https://github.com/quic/toolchain_for_hexagon/issues/6
Signed-off-by: Mukilan Thiyagarajan <quic_mthiyaga@quicinc.com>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Taylor Simpson <tsimpson@quicinc.com>
Message-Id: <20221229092006.10709-2-quic_mthiyaga@quicinc.com>
2023-01-05 09:19:02 -08:00
..
aarch64 linux-user: Provide MADV_* definitions 2022-09-27 09:30:09 +02:00
alpha linux-user: Provide MADV_* definitions 2022-09-27 09:30:09 +02:00
arm linux-user: Provide MADV_* definitions 2022-09-27 09:30:09 +02:00
cris linux-user: Provide MADV_* definitions 2022-09-27 09:30:09 +02:00
generic linux-user: Provide MADV_* definitions 2022-09-27 09:30:09 +02:00
hexagon linux-user/hexagon: fix signal context save & restore 2023-01-05 09:19:02 -08:00
hppa linux-user/hppa: Detect glibc ABORT_INSTRUCTION and EXCP_BREAK handler 2022-11-02 17:14:02 +01:00
i386 linux-user: Add guest memory layout to exception dump 2022-10-25 09:20:40 +02:00
include linux-user/host/s390: Add vector instructions to host_signal_write() 2022-09-23 15:16:16 +02:00
loongarch64 linux-user: Provide MADV_* definitions 2022-09-27 09:30:09 +02:00
m68k linux-user: Provide MADV_* definitions 2022-09-27 09:30:09 +02:00
microblaze linux-user: Provide MADV_* definitions 2022-09-27 09:30:09 +02:00
mips linux-user: Provide MADV_* definitions 2022-09-27 09:30:09 +02:00
mips64 linux-user: Provide MADV_* definitions 2022-09-27 09:30:09 +02:00
nios2 linux-user: Provide MADV_* definitions 2022-09-27 09:30:09 +02:00
openrisc linux-user: Provide MADV_* definitions 2022-09-27 09:30:09 +02:00
ppc linux-user: Provide MADV_* definitions 2022-09-27 09:30:09 +02:00
riscv linux-user: Provide MADV_* definitions 2022-09-27 09:30:09 +02:00
s390x linux-user/s390x: Save/restore fpc when handling a signal 2022-09-27 13:19:05 +02:00
sh4 target/sh4: Fix TB_FLAG_UNALIGN 2022-10-04 12:33:05 -07:00
sparc linux-user: Provide MADV_* definitions 2022-09-27 09:30:09 +02:00
x86_64 linux-user: Provide MADV_* definitions 2022-09-27 09:30:09 +02:00
xtensa linux-user: Provide MADV_* definitions 2022-09-27 09:30:09 +02:00
cpu_loop-common.h linux-user: Add guest memory layout to exception dump 2022-10-25 09:20:40 +02:00
elfload.c linux-user: Set ELF_BASE_PLATFORM for MIPS 2022-09-27 13:19:05 +02:00
errnos.c.inc linux-user: Simplify host <-> target errno conversion using macros 2021-07-12 21:53:35 +02:00
exit.c linux-user: Don't include gdbstub.h in qemu.h 2021-09-13 20:35:45 +02:00
fd-trans.c linux-user: Fix inotify on aarch64 2022-01-27 16:58:33 +01:00
fd-trans.h fd-trans: Fix race condition on reallocation of the translation table. 2021-07-12 21:54:46 +02:00
flat.h linux-user/: fix some comment spelling errors 2020-09-17 20:39:22 +02:00
flatload.c linux-user/flatload.c: Fix setting of image_info::end_code 2022-07-28 19:17:24 +02:00
ioctls.h linux-user: remove conditionals for many fs.h ioctls 2022-10-21 17:46:19 +02:00
linux_loop.h linux-user: implement more loop ioctls 2021-11-29 14:54:17 +01:00
linuxload.c linux-user: Clean up arg_start/arg_end confusion 2022-05-23 08:15:19 +02:00
loader.h linux-user: Split loader-related prototypes into loader.h 2021-09-13 20:35:44 +02:00
main.c plugins: add [pre|post]fork helpers to linux-user 2022-10-06 11:53:41 +01:00
meson.build user: move common-user includes to a subdirectory of {bsd,linux}-user/ 2022-01-12 14:08:29 +01:00
mmap.c accel/tcg: Call tb_invalidate_phys_page for PAGE_RESET 2022-10-26 11:11:28 +10:00
qemu.h linux-user: Honor PT_GNU_STACK 2022-09-06 08:04:25 +01:00
semihost.c semihosting: Remove qemu_semihosting_console_outs 2022-06-28 04:41:20 +05:30
signal-common.h linux-user: Add missing signals in strace output 2022-09-27 09:29:33 +02:00
signal.c linux-user: Add missing signals in strace output 2022-09-27 09:29:33 +02:00
socket.h Supply missing header guards 2019-06-12 13:20:21 +02:00
strace.c linux-user: Implement faccessat2 2022-10-21 17:46:19 +02:00
strace.h linux-user: Have do_syscall() use CPUArchState* instead of void* 2022-05-23 22:47:19 +02:00
strace.list linux-user: Add strace output for timer_settime64() syscall 2022-11-02 17:21:06 +01:00
syscall.c Drop more useless casts from void * to pointer 2022-12-14 16:19:35 +01:00
syscall_defs.h linux-user: Fix struct statfs ABI on loongarch64 2022-10-17 10:28:35 +08:00
syscall_types.h linux-user: implement more loop ioctls 2021-11-29 14:54:17 +01:00
target_flat.h Supply missing header guards 2019-06-12 13:20:21 +02:00
thunk.c linux-user: Move thunk.c from top-level 2021-12-20 10:12:29 -08:00
trace-events linux-user: Rename user_force_sig tracepoint to match function name 2022-01-18 12:41:42 +01:00
trace.h trace: switch position of headers to what Meson requires 2020-08-21 06:18:24 -04:00
uaccess.c linux-user: Split linux-user internals out of qemu.h 2021-09-13 20:35:45 +02:00
uname.c linux-user: Remove pointless CPU{ARCH}State casts 2022-05-23 22:47:20 +02:00
uname.h linux-user: Have do_syscall() use CPUArchState* instead of void* 2022-05-23 22:47:19 +02:00
user-internals.h linux-user: Add partial support for MADV_DONTNEED 2022-06-24 10:00:00 +02:00
user-mmap.h linux-user: Add partial support for MADV_DONTNEED 2022-06-24 10:00:00 +02:00
vm86.c linux-user: Split linux-user internals out of qemu.h 2021-09-13 20:35:45 +02:00