From: Bodo Stroesser With this patch, we change the way we handle switching from PTRACE_SYSEMU to PTRACE_{SINGLESTEP,SYSCALL}, to free TIF_SYSCALL_EMU from double use as a preparation for PTRACE_SYSEMU_SINGLESTEP extension, without changing the behavior of the host kernel. Signed-off-by: Bodo Stroesser Signed-off-by: Paolo 'Blaisorblade' Giarrusso Cc: Jeff Dike Signed-off-by: Andrew Morton --- arch/i386/kernel/entry.S | 8 +++++++- arch/i386/kernel/ptrace.c | 43 ++++++++++++++----------------------------- 2 files changed, 21 insertions(+), 30 deletions(-) diff -puN arch/i386/kernel/entry.S~uml-support-reorganize-ptrace_sysemu-support arch/i386/kernel/entry.S --- devel/arch/i386/kernel/entry.S~uml-support-reorganize-ptrace_sysemu-support 2005-07-27 12:16:14.000000000 -0700 +++ devel-akpm/arch/i386/kernel/entry.S 2005-07-27 12:16:14.000000000 -0700 @@ -339,12 +339,18 @@ syscall_trace_entry: xorl %edx,%edx call do_syscall_trace cmpl $0, %eax - jne syscall_exit # ret != 0 -> running under PTRACE_SYSEMU, + jne syscall_skip # ret != 0 -> running under PTRACE_SYSEMU, # so must skip actual syscall movl ORIG_EAX(%esp), %eax cmpl $(nr_syscalls), %eax jnae syscall_call jmp syscall_exit +syscall_skip: + cli # make sure we don't miss an interrupt + # setting need_resched or sigpending + # between sampling and the iret + movl TI_flags(%ebp), %ecx + jmp work_pending # perform syscall exit tracing ALIGN diff -puN arch/i386/kernel/ptrace.c~uml-support-reorganize-ptrace_sysemu-support arch/i386/kernel/ptrace.c --- devel/arch/i386/kernel/ptrace.c~uml-support-reorganize-ptrace_sysemu-support 2005-07-27 12:16:14.000000000 -0700 +++ devel-akpm/arch/i386/kernel/ptrace.c 2005-07-27 12:16:14.000000000 -0700 @@ -515,21 +515,14 @@ asmlinkage int sys_ptrace(long request, ret = -EIO; if (!valid_signal(data)) break; - /* If we came here with PTRACE_SYSEMU and now continue with - * PTRACE_SYSCALL, entry.S used to intercept the syscall return. - * But it shouldn't! - * So we don't clear TIF_SYSCALL_EMU, which is always unused in - * this special case, to remember, we came from SYSEMU. That - * flag will be cleared by do_syscall_trace(). - */ if (request == PTRACE_SYSEMU) { set_tsk_thread_flag(child, TIF_SYSCALL_EMU); - } else if (request == PTRACE_CONT) { - clear_tsk_thread_flag(child, TIF_SYSCALL_EMU); - } - if (request == PTRACE_SYSCALL) { + clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); + } else if (request == PTRACE_SYSCALL) { set_tsk_thread_flag(child, TIF_SYSCALL_TRACE); + clear_tsk_thread_flag(child, TIF_SYSCALL_EMU); } else { + clear_tsk_thread_flag(child, TIF_SYSCALL_EMU); clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); } child->exit_code = data; @@ -558,8 +551,7 @@ asmlinkage int sys_ptrace(long request, ret = -EIO; if (!valid_signal(data)) break; - /*See do_syscall_trace to know why we don't clear - * TIF_SYSCALL_EMU.*/ + clear_tsk_thread_flag(child, TIF_SYSCALL_EMU); clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); set_singlestep(child); child->exit_code = data; @@ -694,7 +686,7 @@ void send_sigtrap(struct task_struct *ts __attribute__((regparm(3))) int do_syscall_trace(struct pt_regs *regs, int entryexit) { - int is_sysemu, is_systrace, is_singlestep, ret = 0; + int is_sysemu, is_singlestep, ret = 0; /* do the secure computing check first */ secure_computing(regs->orig_eax); @@ -705,25 +697,13 @@ int do_syscall_trace(struct pt_regs *reg goto out; is_sysemu = test_thread_flag(TIF_SYSCALL_EMU); - is_systrace = test_thread_flag(TIF_SYSCALL_TRACE); is_singlestep = test_thread_flag(TIF_SINGLESTEP); - /* We can detect the case of coming from PTRACE_SYSEMU and now running - * with PTRACE_SYSCALL or PTRACE_SINGLESTEP, by TIF_SYSCALL_EMU being - * set additionally. - * If so let's reset the flag and return without action (no singlestep - * nor syscall tracing, since no actual step has been executed). - */ - if (is_sysemu && (is_systrace || is_singlestep)) { - clear_thread_flag(TIF_SYSCALL_EMU); - goto out; - } - /* Fake a debug trap */ - if (test_thread_flag(TIF_SINGLESTEP)) + if (is_singlestep) send_sigtrap(current, regs, 0); - if (!is_systrace && !is_sysemu) + if (!test_thread_flag(TIF_SYSCALL_TRACE) && !is_sysemu) goto out; /* the 0x80 provides a way for the tracing parent to distinguish @@ -745,5 +725,10 @@ int do_syscall_trace(struct pt_regs *reg if (unlikely(current->audit_context) && !entryexit) audit_syscall_entry(current, AUDIT_ARCH_I386, regs->orig_eax, regs->ebx, regs->ecx, regs->edx, regs->esi); - return ret; + if (ret == 0) + return 0; + + if (unlikely(current->audit_context)) + audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax); + return 1; } _