Preparatory patch for "new" x86 personality detection

* syscall.c: Move PT_FLAGS_COMPAT define to its only user, get_scno().
Rename arm_regs_union's fields to names less likely to collide with
system defines.
(get_regs): Use sizeof(arm_regs_union) instead of sizeof(aarch64_regs).
This should be the same, but htis way it's cleaner.
Remove __X32_SYSCALL_MASK and use __X32_SYSCALL_BIT instead.
Explain 64-bit check in X32 build better.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/syscall.c b/syscall.c
index a73651de188fa6fa7f0c47f50cc7f04661a3ad5f..f403c44187af6f48969f3fb3bd2f56153992a08a 100644 (file)
--- a/syscall.c
+++ b/syscall.c
@@ -71,12 +71,6 @@
 # include <elf.h>
 #endif
 
-#if defined(TILE)
-# ifndef PT_FLAGS_COMPAT
-#  define PT_FLAGS_COMPAT 0x10000  /* from Linux 3.8 on */
-# endif
-#endif
-
 #ifndef ERESTARTSYS
 # define ERESTARTSYS   512
 #endif
@@ -682,13 +676,13 @@ static long r0;
 struct pt_regs arm_regs; /* not static */
 #elif defined(AARCH64)
 static union {
-       struct user_pt_regs aarch64;
-       struct arm_pt_regs  arm;
+       struct user_pt_regs aarch64_r;
+       struct arm_pt_regs  arm_r;
 } arm_regs_union;
-# define aarch64_regs arm_regs_union.aarch64
-# define arm_regs     arm_regs_union.arm
+# define aarch64_regs arm_regs_union.aarch64_r
+# define arm_regs     arm_regs_union.arm_r
 static struct iovec aarch64_io = {
-       .iov_base = &aarch64_regs
+       .iov_base = &arm_regs_union
 };
 #elif defined(ALPHA)
 static long r0;
@@ -869,8 +863,8 @@ void get_regs(pid_t pid)
 # elif defined(ARM)
        get_regs_error = ptrace(PTRACE_GETREGS, pid, NULL, (void *)&arm_regs);
 # elif defined(AARCH64)
-       /*aarch64_io.iov_base = &aarch64_regs; - already is */
-       aarch64_io.iov_len = sizeof(aarch64_regs);
+       /*aarch64_io.iov_base = &arm_regs_union; - already is */
+       aarch64_io.iov_len = sizeof(arm_regs_union);
        get_regs_error = ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, (void *)&aarch64_io);
 #  if 0
        /* Paranoia checks */
@@ -1020,10 +1014,6 @@ get_scno(struct tcb *tcp)
 # ifndef __X32_SYSCALL_BIT
 #  define __X32_SYSCALL_BIT    0x40000000
 # endif
-# ifndef __X32_SYSCALL_MASK
-#  define __X32_SYSCALL_MASK   __X32_SYSCALL_BIT
-# endif
-
        int currpers;
        scno = x86_64_regs.orig_rax;
 
@@ -1038,7 +1028,7 @@ get_scno(struct tcb *tcp)
                case 0x33:
                        if (x86_64_regs.ds == 0x2b) {
                                currpers = 2;
-                               scno &= ~__X32_SYSCALL_MASK;
+                               scno &= ~__X32_SYSCALL_BIT;
                        } else
                                currpers = 0;
                        break;
@@ -1080,24 +1070,19 @@ get_scno(struct tcb *tcp)
                        break;
        }
 # endif
+
 # ifdef X32
-       /* Value of currpers:
-        *   0: 64 bit
-        *   1: 32 bit
-        *   2: X32
-        * Value of current_personality:
-        *   0: X32
-        *   1: 32 bit
+       /* If we are built for a x32 system, then personality 0 is x32
+        * (not x86_64), and stracing of x86_64 apps is not supported.
+        * Stracing of i386 apps is still supported.
         */
-       switch (currpers) {
-               case 0:
-                       fprintf(stderr, "syscall_%lu (...) in unsupported "
-                                       "64-bit mode of process PID=%d\n",
-                               scno, tcp->pid);
-                       return 0;
-               case 2:
-                       currpers = 0;
+       if (currpers == 0) {
+               fprintf(stderr, "syscall_%lu(...) in unsupported "
+                               "64-bit mode of process PID=%d\n",
+                       scno, tcp->pid);
+               return 0;
        }
+       currpers &= ~2; /* map 2,1 to 0,1 */
 # endif
        update_personality(tcp, currpers);
 #elif defined(IA64)
@@ -1323,6 +1308,9 @@ get_scno(struct tcb *tcp)
 # ifdef __tilepro__
        currpers = 1;
 # else
+#  ifndef PT_FLAGS_COMPAT
+#   define PT_FLAGS_COMPAT 0x10000  /* from Linux 3.8 on */
+#  endif
        if (tile_regs.flags & PT_FLAGS_COMPAT)
                currpers = 1;
        else