On 8/17/22 23:05, Ilya Leoshkevich wrote: > Hi, > > I noticed that when we get a SEGV due to jumping to non-readable > memory, sometimes si_addr and program counter in siginfo_t are slightly > off. I tracked this down to the assumption that translators stop before > the end of a page, while in reality they may stop right after it.
Hi, Could this be related to issue 1155 [1]? On RISC-V, I'm getting incorrect [m|s]tval/[m|s]epc combinations for page faults in system emulation and incorrect si_addr and program counter on SIGSEGV in user emulation. Since it seems to only affect instructions that cross page boundaries, and RISC-V also has variable length instructions, it seems that I've run into the same problem as what is fixed here. Could this fix be extended be extended to targets/riscv? dram [1]: https://gitlab.com/qemu-project/qemu/-/issues/1155 > Patch 1 fixes an invalidation issue, which may prevent SEGV from > happening altogether. > Patches 2-3 fix the main issue on x86_64 and s390x. Many other > architectures have fixed-size instructions and are not affected. > Patch 4 adds tests. > > Note: this series depends on [1]. > > Best regards, > Ilya > > v1: https://lists.gnu.org/archive/html/qemu-devel/2022-08/msg00822.html > v1 -> v2: Fix individual translators instead of translator_loop > (Peter). > > v2: https://lists.gnu.org/archive/html/qemu-devel/2022-08/msg01079.html > v2 -> v3: Peek at the next instruction on s390x (Richard). > Undo more on i386 (Richard). > Check PAGE_EXEC, not PAGE_READ (Peter, Richard). > > v3: https://lists.gnu.org/archive/html/qemu-devel/2022-08/msg01306.html > v3 -> v4: Improve the commit message in patch 1 to better reflect what > exactly is being fixed there. > Factor out the is_same_page() patch (Richard). > Do not touch the common code in the i386 fix (Richard). > > v4: https://lists.gnu.org/archive/html/qemu-devel/2022-08/msg01747.html > v4 -> v5: Drop patch 2. > Use a different fix for the invalidation issue based on > discussion with Richard [2]. > > [1] https://lists.gnu.org/archive/html/qemu-devel/2022-08/msg02472.html > [2] https://lists.gnu.org/archive/html/qemu-devel/2022-08/msg02556.html > > Ilya Leoshkevich (4): > linux-user: Clear tb_jmp_cache on mprotect() > target/s390x: Make translator stop before the end of a page > target/i386: Make translator stop before the end of a page > tests/tcg: Test siginfo_t contents when jumping to non-readable pages > > linux-user/mmap.c | 14 +++ > target/i386/tcg/translate.c | 25 +++++- > target/s390x/tcg/translate.c | 15 +++- > tests/tcg/multiarch/noexec.h | 114 ++++++++++++++++++++++++ > tests/tcg/s390x/Makefile.target | 1 + > tests/tcg/s390x/noexec.c | 145 +++++++++++++++++++++++++++++++ > tests/tcg/x86_64/Makefile.target | 3 +- > tests/tcg/x86_64/noexec.c | 116 +++++++++++++++++++++++++ > 8 files changed, 427 insertions(+), 6 deletions(-) > create mode 100644 tests/tcg/multiarch/noexec.h > create mode 100644 tests/tcg/s390x/noexec.c > create mode 100644 tests/tcg/x86_64/noexec.c >
