x86 ptrace: unify syscall tracing

This unifies and cleans up the syscall tracing code on i386 and x86_64.

Using a single function for entry and exit tracing on 32-bit made the
do_syscall_trace() into some terrible spaghetti.  The logic is clear and
simple using separate syscall_trace_enter() and syscall_trace_leave()
functions as on 64-bit.

The unification adds PTRACE_SYSEMU and PTRACE_SYSEMU_SINGLESTEP support
on x86_64, for 32-bit ptrace() callers and for 64-bit ptrace() callers
tracing either 32-bit or 64-bit tasks.  It behaves just like 32-bit.

Changing syscall_trace_enter() to return the syscall number shortens
all the assembly paths, while adding the SYSEMU feature in a simple way.

Signed-off-by: Roland McGrath <roland@redhat.com>

1 files changed, 10 insertions, 7 deletions

diff --git a/include/asm-x86/thread_info.h b/include/asm-x86/thread_info.h
index fb8d3cdf143..b2702a1eeac 100644
--- a/include/asm-x86/thread_info.h
+++ b/include/asm-x86/thread_info.h
@@ -75,9 +75,7 @@ struct thread_info {
 #define TIF_NEED_RESCHED        3       /* rescheduling necessary */
 #define TIF_SINGLESTEP          4       /* reenable singlestep on user return*/
 #define TIF_IRET                5       /* force IRET */
-#ifdef CONFIG_X86_32
 #define TIF_SYSCALL_EMU         6       /* syscall emulation active */
-#endif
 #define TIF_SYSCALL_AUDIT       7       /* syscall auditing active */
 #define TIF_SECCOMP             8       /* secure computing */
 #define TIF_MCE_NOTIFY          10      /* notify userspace of an MCE */
@@ -100,11 +98,7 @@ struct thread_info {
 #define _TIF_SINGLESTEP         (1 << TIF_SINGLESTEP)
 #define _TIF_NEED_RESCHED       (1 << TIF_NEED_RESCHED)
 #define _TIF_IRET               (1 << TIF_IRET)
-#ifdef CONFIG_X86_32
 #define _TIF_SYSCALL_EMU        (1 << TIF_SYSCALL_EMU)
-#else
-#define _TIF_SYSCALL_EMU        0
-#endif
 #define _TIF_SYSCALL_AUDIT      (1 << TIF_SYSCALL_AUDIT)
 #define _TIF_SECCOMP            (1 << TIF_SECCOMP)
 #define _TIF_MCE_NOTIFY         (1 << TIF_MCE_NOTIFY)
@@ -121,11 +115,20 @@ struct thread_info {
 #define _TIF_DS_AREA_MSR        (1 << TIF_DS_AREA_MSR)
 #define _TIF_BTS_TRACE_TS       (1 << TIF_BTS_TRACE_TS)
 
+/* work to do in syscall_trace_enter() */
+#define _TIF_WORK_SYSCALL_ENTRY \
+        (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | \
+         _TIF_SYSCALL_AUDIT | _TIF_SECCOMP)
+
+/* work to do in syscall_trace_leave() */
+#define _TIF_WORK_SYSCALL_EXIT  \
+        (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SINGLESTEP)
+
 /* work to do on interrupt/exception return */
 #define _TIF_WORK_MASK                                                  \
         (0x0000FFFF &                                                   \
          ~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|                       \
-         _TIF_SECCOMP|_TIF_SYSCALL_EMU))
+           _TIF_SINGLESTEP|_TIF_SECCOMP|_TIF_SYSCALL_EMU))
 
 /* work to do on any return to user space */
 #define _TIF_ALLWORK_MASK (0x0000FFFF & ~_TIF_SECCOMP)