diff options
author | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2016-06-10 05:30:17 -0300 |
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committer | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2016-06-10 05:30:17 -0300 |
commit | d635711daa98be86d4c7fd01499c34f566b54ccb (patch) | |
tree | aa5cc3760a27c3d57146498cb82fa549547de06c /arch/x86/include/uapi/asm/sigcontext.h | |
parent | c91265cd0efb83778f015b4d4b1129bd2cfd075e (diff) |
Linux-libre 4.6.2-gnu
Diffstat (limited to 'arch/x86/include/uapi/asm/sigcontext.h')
-rw-r--r-- | arch/x86/include/uapi/asm/sigcontext.h | 32 |
1 files changed, 30 insertions, 2 deletions
diff --git a/arch/x86/include/uapi/asm/sigcontext.h b/arch/x86/include/uapi/asm/sigcontext.h index d485232f1..62d4111c1 100644 --- a/arch/x86/include/uapi/asm/sigcontext.h +++ b/arch/x86/include/uapi/asm/sigcontext.h @@ -256,7 +256,7 @@ struct sigcontext_64 { __u16 cs; __u16 gs; __u16 fs; - __u16 __pad0; + __u16 ss; __u64 err; __u64 trapno; __u64 oldmask; @@ -341,9 +341,37 @@ struct sigcontext { __u64 rip; __u64 eflags; /* RFLAGS */ __u16 cs; + + /* + * Prior to 2.5.64 ("[PATCH] x86-64 updates for 2.5.64-bk3"), + * Linux saved and restored fs and gs in these slots. This + * was counterproductive, as fsbase and gsbase were never + * saved, so arch_prctl was presumably unreliable. + * + * These slots should never be reused without extreme caution: + * + * - Some DOSEMU versions stash fs and gs in these slots manually, + * thus overwriting anything the kernel expects to be preserved + * in these slots. + * + * - If these slots are ever needed for any other purpose, + * there is some risk that very old 64-bit binaries could get + * confused. I doubt that many such binaries still work, + * though, since the same patch in 2.5.64 also removed the + * 64-bit set_thread_area syscall, so it appears that there + * is no TLS API beyond modify_ldt that works in both pre- + * and post-2.5.64 kernels. + * + * If the kernel ever adds explicit fs, gs, fsbase, and gsbase + * save/restore, it will most likely need to be opt-in and use + * different context slots. + */ __u16 gs; __u16 fs; - __u16 __pad0; + union { + __u16 ss; /* If UC_SIGCONTEXT_SS */ + __u16 __pad0; /* Alias name for old (!UC_SIGCONTEXT_SS) user-space */ + }; __u64 err; __u64 trapno; __u64 oldmask; |