Messages in this thread | | | From | Andy Lutomirski <> | Subject | [PATCH v3 0/4] x86: sigcontext fixes, again | Date | Mon, 25 Jan 2016 13:34:11 -0800 |
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This is take 2 at fixing x86 64-bit signals wrt SS. After a lot of thought, this is not controlled by any flags -- I would much prefer to avoid opt-in behavior. Instead, it just tries hard to avoid triggering the cases that break DOSEMU.
Stas, this now seems to pass the test you sent me. It works with stock dosemu2 (I haven't tested classic dosemu because I can't get it to work regardless). It also works with a patched dosemu2 that bypasses the userspace trampoline:
https://github.com/amluto/dosemu2/commit/571b4d08dc885b7a133e444a2ad23e0d21366206
With this applied, all of the x86 selftests pass on x86_64. That wasn't the case before -- ldt_gdt_64 was broken.
This is a bit risky, and another option would be to do nothing at all. Then we'd disable the problematic self-tests (sigh), and DOSEMU and similar tools will be stuck using gross hacks even on new kernels.
Changes from v2: - Rebased (which wasn't quite trivial since the headers were rearranged) - Slightly improved a comment in patch 1. - Tidy up changelogs a bit.
Changes from v1: - Comment fixes - Fix screwed up uaccess that broke things
Andy Lutomirski (4): x86/signal/64: Add a comment about sigcontext->fs and gs x86/signal/64: Fix SS if needed when delivering a 64-bit signal x86/signal/64: Re-add support for SS in the 64-bit signal context selftests/x86: Add tests for UC_SIGCONTEXT_SS and UC_STRICT_RESTORE_SS
arch/x86/include/asm/desc_defs.h | 23 +++ arch/x86/include/asm/sighandling.h | 1 - arch/x86/include/uapi/asm/sigcontext.h | 26 +++- arch/x86/include/uapi/asm/ucontext.h | 43 +++++- arch/x86/kernel/signal.c | 114 ++++++++++++--- tools/testing/selftests/x86/Makefile | 7 +- tools/testing/selftests/x86/sigreturn.c | 240 ++++++++++++++++++++++++++++---- 7 files changed, 394 insertions(+), 60 deletions(-)
-- 2.5.0
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