(SYSCALL_ERROR_HANDLER): Always define, not only #ifndef PIC.

(DO_CALL): Pass fifth argument correctly in R4.
(PSEUDO): Correct test for error, call syscall_error through PLT if PIC.

diff --git a/sysdeps/unix/sysv/linux/arm/sysdep.h b/sysdeps/unix/sysv/linux/arm/sysdep.h
index 3b7ffe0..dd1b6f4 100644 (file)
--- a/sysdeps/unix/sysv/linux/arm/sysdep.h
+++ b/sysdeps/unix/sysv/linux/arm/sysdep.h
@@ -45,28 +45,64 @@
    is a real error number.  Linus said he will make sure the no syscall
    returns a value in -1 .. -4095 as a valid result so we can savely
    test with -4095.  */
+
 #undef PSEUDO
 #define        PSEUDO(name, syscall_name, args)                                      \
   .text;                                                                     \
+  .type syscall_error,%function                                                      \
   ENTRY (name)                                                               \
     DO_CALL (args, syscall_name);                                            \
     cmn r0, $4096;                                                           \
-    bgt syscall_error;
+    bhs PLTJMP(syscall_error);
 
 #undef PSEUDO_END
 #define        PSEUDO_END(name)                                                      \
   SYSCALL_ERROR_HANDLER                                                              \
   END (name)
 
-#ifndef PIC
 #define SYSCALL_ERROR_HANDLER  /* Nothing here; code in sysdep.S is used.  */
-#else
-#error Aiee
-#endif /* PIC */
+
+/* Linux takes system call args in registers:
+       syscall number  in the SWI instruction
+       arg 1           r0
+       arg 2           r1
+       arg 3           r2
+       arg 4           r3
+       arg 5           r4      (this is different from the APCS convention)
+
+   The compiler is going to form a call by coming here, through PSEUDO, with
+   arguments
+       syscall number  in the DO_CALL macro
+       arg 1           r0
+       arg 2           r1
+       arg 3           r2
+       arg 4           r3
+       arg 5           [sp]
+
+   We need to shuffle values between R4 and the stack so that the caller's
+   R4 is not corrupted, and the kernel sees the right argument there.
+
+*/
 
 #undef DO_CALL
-#define DO_CALL(args, syscall_name)                                          \
-    swi SYS_ify (syscall_name);
+#define DO_CALL(args, syscall_name)            \
+    DOARGS_##args                              \
+    swi SYS_ify (syscall_name);                \
+    UNDOARGS_##args
+
+#define DOARGS_0 /* nothing */
+#define DOARGS_1 /* nothing */
+#define DOARGS_2 /* nothing */
+#define DOARGS_3 /* nothing */
+#define DOARGS_4 /* nothing */
+#define DOARGS_5 ldr ip, [sp]; str r4, [sp]; mov r4, ip;
+
+#define UNDOARGS_0 /* nothing */
+#define UNDOARGS_1 /* nothing */
+#define UNDOARGS_2 /* nothing */
+#define UNDOARGS_3 /* nothing */
+#define UNDOARGS_4 /* nothing */
+#define UNDOARGS_5 ldr r4, [sp];
 
 #endif /* ASSEMBLER */