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| author | Konstantin Belousov <kib@FreeBSD.org> | 2016-08-27 23:03:23 +0000 |
|---|---|---|
| committer | Konstantin Belousov <kib@FreeBSD.org> | 2016-08-27 23:03:23 +0000 |
| commit | da6e468936ace83c59c3ee466ed93ede41850ec9 (patch) | |
| tree | 71c0abadb9ad97fdc7174185151d5242a70a5465 /lib/libc/amd64 | |
| parent | 11d3ad2eab8e764510c299132015481f5ba72f29 (diff) | |
| download | src-da6e468936ace83c59c3ee466ed93ede41850ec9.tar.gz src-da6e468936ace83c59c3ee466ed93ede41850ec9.zip | |
Do not obliterate errno value in the main thread during ptrace(2) call on x86.
Since ptrace(2) syscall can return -1 for non-error situations, libc
wrappers set errno to 0 before performing the syscall, as the service
to the caller. On both i386 and amd64, the errno symbol was directly
referenced, which only works correctly in single-threaded process.
Change assembler wrappers for ptrace(2) to get current thread errno
location by calling __error(). Allow __error interposing, as
currently allowed in cerror().
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Notes
Notes:
svn path=/head/; revision=304928
Diffstat (limited to 'lib/libc/amd64')
| -rw-r--r-- | lib/libc/amd64/sys/ptrace.S | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/lib/libc/amd64/sys/ptrace.S b/lib/libc/amd64/sys/ptrace.S index 9c4628da8ce4..c367a4ea12d1 100644 --- a/lib/libc/amd64/sys/ptrace.S +++ b/lib/libc/amd64/sys/ptrace.S @@ -38,14 +38,16 @@ __FBSDID("$FreeBSD$"); #include "SYS.h" + .globl CNAME(__error) + .type CNAME(__error),@function + ENTRY(ptrace) - xorl %eax,%eax #ifdef PIC - movq PIC_GOT(CNAME(errno)),%r8 - movl %eax,(%r8) + callq PIC_PLT(CNAME(__error)) #else - movl %eax,CNAME(errno)(%rip) + callq CNAME(__error) #endif + movl $0,(%rax) mov $SYS_ptrace,%eax KERNCALL jb HIDENAME(cerror) |