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2023-01-05linux-user/hexagon: fix signal context save & restoreMukilan Thiyagarajan
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>
2021-12-19linux-user: Rename TARGET_QEMU_ESIGRETURN to QEMU_ESIGRETURNRichard Henderson
This value is fully internal to qemu, and so is not a TARGET define. Reviewed-by: Warner Losh <imp@bsdimp.com> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2021-10-01linux-user/hexagon: Implement setup_sigtrampRichard Henderson
Continue to initialize the words on the stack, as documented. However, use the off-stack trampoline. Reviewed-by: Taylor Simpson <tsimpson@quicinc.com> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Message-Id: <20210929130553.121567-9-richard.henderson@linaro.org> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
2021-09-13linux-user: Split linux-user internals out of qemu.hPeter Maydell
qemu.h is included in various non-linux-user files (which mostly want the TaskState struct and the functions for doing usermode access to guest addresses like lock_user(), unlock_user(), get_user*(), etc). Split out the parts that are only used in linux-user itself into a new user-internals.h. This leaves qemu.h with basically three things: * the definition of the TaskState struct * the user-access functions and macros * do_brk() all of which are needed by code outside linux-user that includes qemu.h. The addition of all the extra #include lines was done with sed -i '/include.*qemu\.h/a #include "user-internals.h"' $(git grep -l 'include.*qemu\.h' linux-user) (and then undoing the change to fpa11.h). Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-Id: <20210908154405.15417-8-peter.maydell@linaro.org> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
2021-05-15linux-user: Pass CPUArchState to target_restore_altstackRichard Henderson
In most cases we were already passing get_sp_from_cpustate directly to the function. In other cases, we were passing a local variable which already contained the same value. In the rest of the cases, we were passing the stack pointer out of env directly. Reviewed by: Warner Losh <imp@bsdimp.com> Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Message-Id: <20210426025334.1168495-5-richard.henderson@linaro.org> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
2021-05-15linux-user: Use target_restore_altstack in all sigreturnRichard Henderson
Note that target_restore_altstack uses the host memory pointer that we have already verified, so TARGET_EFAULT is not a possible return value. Note that using -EFAULT was a bug. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Message-Id: <20210426025334.1168495-3-richard.henderson@linaro.org> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
2021-02-18Hexagon (linux-user/hexagon) Linux user emulationTaylor Simpson
Implementation of Linux user emulation for Hexagon Some common files modified in addition to new files in linux-user/hexagon Acked-by: Laurent Vivier <laurent@vivier.eu> Signed-off-by: Taylor Simpson <tsimpson@quicinc.com> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-Id: <1612763186-18161-31-git-send-email-tsimpson@quicinc.com> [rth: Fix termbits.h on review by Laurent] Signed-off-by: Richard Henderson <richard.henderson@linaro.org>