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[PATCH] Uml support: reorganize PTRACE_SYSEMU support 

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 <bstroesser@fujitsu-siemens.com>
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Bodo Stroesser 2005-09-03 15:57:19 -07:00 committed by Linus Torvalds
parent ed75e8d580
commit c8c86cecd1
2 changed files with 21 additions and 30 deletions
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8
arch/i386/kernel/entry.S
View File

@ -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

43
arch/i386/kernel/ptrace.c
View File

@ -515,21 +515,14 @@ asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
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, long pid, long addr, long data)
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 *tsk, struct pt_regs *regs, int error_code)
__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 *regs, int entryexit)
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 *regs, int entryexit)
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;
}