riscv/qemu: QEMU main repository: Please see https://www.qemu.org/docs/master/devel/submitting-a-patch.html for how to submit changes to QEMU. Pull Requests are ignored. Please only use release tarballs from the QEMU website. http://www.qemu.org - qemu

QEMU main repository: Please see https://www.qemu.org/docs/master/devel/submitting-a-patch.html for how to submit changes to QEMU. Pull Requests are ignored. Please only use release tarballs from the QEMU website. http://www.qemu.org

emulation kvm qemu virtualization

History

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>		3 years ago
..
cpu_loop.c	Remove qemu-common.h include from most units	4 years ago
signal.c	linux-user/hexagon: fix signal context save & restore	3 years ago
sockbits.h	Hexagon (linux-user/hexagon) Linux user emulation	5 years ago
syscall_nr.h	linux-user: update syscall_nr.h to Linux v5.13	5 years ago
target_cpu.h	Hexagon (linux-user/hexagon) Linux user emulation	5 years ago
target_elf.h	Hexagon (linux-user/hexagon) Linux user emulation	5 years ago
target_errno_defs.h	linux-user: Extract target errno to 'target_errno_defs.h'	5 years ago
target_fcntl.h	Hexagon (linux-user/hexagon) Linux user emulation	5 years ago
target_mman.h	linux-user: Provide MADV_* definitions	4 years ago
target_prctl.h	linux-user: Split out do_prctl and subroutines	4 years ago
target_resource.h	linux-user: Move generic TARGET_RLIMIT* definitions to generic/target_resource.h	4 years ago
target_signal.h	Clean up decorations and whitespace around header guards	4 years ago
target_structs.h	linux-user: Move target_struct.h generic definitions to generic/	4 years ago
target_syscall.h	Hexagon (linux-user/hexagon) Linux user emulation	5 years ago
termbits.h	Hexagon (linux-user/hexagon) Linux user emulation	5 years ago