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authorRoland McGrath <roland@redhat.com>2009-09-22 19:46:34 -0400
committerRoland McGrath <roland@redhat.com>2009-09-22 23:33:42 -0400
commitb60e714dc3ef2a2541e3b262b8b742ba08a07fc0 (patch)
tree2babd0350d90b3892e702726a6422c0091ab7d80 /arch/x86
parent7fa07729e439a6184bd824746d06a49cca553f15 (diff)
x86: ptrace: sysret path should reach syscall_trace_leave
If TIF_SYSCALL_TRACE or TIF_SINGLESTEP is set while inside a syscall, the path back to user mode should get to syscall_trace_leave. This does happen in most circumstances. The exception to this is on the 64-bit syscall fastpath, when no such flag was set on syscall entry and nothing else has punted it off the fastpath for exit. That one exit fastpath fails to check for _TIF_WORK_SYSCALL_EXIT flags. This makes the behavior inconsistent with what 32-bit tasks see and what the native 32-bit kernel always does, and what 64-bit tasks see in all cases where the iret path is taken anyhow. Perhaps the only example that is affected is a ptrace stop inside do_fork (for PTRACE_O_TRACE{CLONE,FORK,VFORK,VFORKDONE}). Other syscalls with internal ptrace stop points (execve) already take the iret exit path for unrelated reasons. Test cases for both PTRACE_SYSCALL and PTRACE_SINGLESTEP variants are at: http://sources.redhat.com/cgi-bin/cvsweb.cgi/~checkout~/tests/ptrace-tests/tests/syscall-from-clone.c?cvsroot=systemtap http://sources.redhat.com/cgi-bin/cvsweb.cgi/~checkout~/tests/ptrace-tests/tests/step-from-clone.c?cvsroot=systemtap There was no special benefit to the sysret path's special path to call do_notify_resume, because it always takes the iret exit path at the end. So this change just makes the sysret exit path join the iret exit path for all the signals and ptrace cases. The fastpath still applies to the plain syscall-audit and resched cases. Signed-off-by: Roland McGrath <roland@redhat.com> CC: Oleg Nesterov <oleg@redhat.com>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kernel/entry_64.S22
1 files changed, 8 insertions, 14 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 681c3fda7391..b5c061f8f358 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -536,20 +536,13 @@ sysret_signal:
536 bt $TIF_SYSCALL_AUDIT,%edx 536 bt $TIF_SYSCALL_AUDIT,%edx
537 jc sysret_audit 537 jc sysret_audit
538#endif 538#endif
539 /* edx: work flags (arg3) */ 539 /*
540 leaq -ARGOFFSET(%rsp),%rdi # &pt_regs -> arg1 540 * We have a signal, or exit tracing or single-step.
541 xorl %esi,%esi # oldset -> arg2 541 * These all wind up with the iret return path anyway,
542 SAVE_REST 542 * so just join that path right now.
543 FIXUP_TOP_OF_STACK %r11 543 */
544 call do_notify_resume 544 FIXUP_TOP_OF_STACK %r11, -ARGOFFSET
545 RESTORE_TOP_OF_STACK %r11 545 jmp int_check_syscall_exit_work
546 RESTORE_REST
547 movl $_TIF_WORK_MASK,%edi
548 /* Use IRET because user could have changed frame. This
549 works because ptregscall_common has called FIXUP_TOP_OF_STACK. */
550 DISABLE_INTERRUPTS(CLBR_NONE)
551 TRACE_IRQS_OFF
552 jmp int_with_check
553 546
554badsys: 547badsys:
555 movq $-ENOSYS,RAX-ARGOFFSET(%rsp) 548 movq $-ENOSYS,RAX-ARGOFFSET(%rsp)
@@ -654,6 +647,7 @@ int_careful:
654int_very_careful: 647int_very_careful:
655 TRACE_IRQS_ON 648 TRACE_IRQS_ON
656 ENABLE_INTERRUPTS(CLBR_NONE) 649 ENABLE_INTERRUPTS(CLBR_NONE)
650int_check_syscall_exit_work:
657 SAVE_REST 651 SAVE_REST
658 /* Check for syscall exit trace */ 652 /* Check for syscall exit trace */
659 testl $_TIF_WORK_SYSCALL_EXIT,%edx 653 testl $_TIF_WORK_SYSCALL_EXIT,%edx