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# This is a work round for a fairly serious GCC compiler bug - when
# the syscall assembler overwrites r7 (required on thumb) the
# compiler fails to protect the register when it is using it as a
# frame pointer.
#
--- uClibc-0.9.28/libc/sysdeps/linux/arm/bits/syscalls.h 2005-09-12 17:51:26.062205918 -0700
+++ uClibc-0.9.28/libc/sysdeps/linux/arm/bits/syscalls.h 2005-09-12 18:16:15.507930828 -0700
@@ -111,6 +111,11 @@
} \
(int) _sys_result; })
#else
+#if 0
+/* This doesn't work because GCC uses r7 as a frame pointer in
+ * some cases and doesn't notice that the _r7 value changes
+ * it, resulting in mysterious crashes after the SWI.
+ */
#define INTERNAL_SYSCALL(name, err, nr, args...) \
({ unsigned int _sys_result; \
{ \
@@ -124,6 +129,28 @@
_sys_result = _a1; \
} \
(int) _sys_result; })
+#else
+/* So hide the use of r7 from the compiler, this would be a lot
+ * easier but for the fact that the syscalls can exceed 255.
+ * For the moment the LOAD_ARG_7 is sacrificed.
+ */
+#define INTERNAL_SYSCALL(name, err, nr, args...) \
+ ({ unsigned int _sys_result; \
+ { \
+ register int _a1 asm ("a1"); \
+ LOAD_ARGS_##nr (args) \
+ register int _v3 asm ("v3") = (int) (SYS_ify(name)); \
+ asm volatile ("push {r7}\n" \
+ "\tmov r7, v3\n" \
+ "\tswi 0 @ syscall " #name "\n" \
+ "\tpop {r7}" \
+ : "=r" (_a1) \
+ : "r" (_v3) ASM_ARGS_##nr \
+ : "memory"); \
+ _sys_result = _a1; \
+ } \
+ (int) _sys_result; })
+#endif
#endif
#undef INTERNAL_SYSCALL_ERROR_P
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