On 14 Jan 2000, H. Peter Anvin wrote:
> We probably should add a set of macros that include PIC support
> (_syscallX_pic)... it seems to me the obvious way to deal with this
> seems to push/pop %ebx around the syscall.
>
> -hpa
That sounded easy enough to accomplish that I went ahead and did it;
however, even after digging through the inline-asm info pages and such I
still can't discover what the "last step" to fix it is. I still get
compiler errors using the syscallX_pic versions.
// pic_sys.c
#include "unistd.h"
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>
_syscall0_pic(pid_t, getpid)
_syscall1_pic(pid_t, getsid, pid_t, pid)
_syscall3_pic(pid_t, waitpid, pid_t, pid, int *, status, int, options)
#if 0
_syscall2_pic()
_syscall4_pic()
_syscall5_pic()
_syscall6_pic()
#endif
int main (int argc, char ** argv)
{
int status;
pid_t pid;
pid = getpid();
printf("0: %d\n", (int)pid);
printf("1: %d\n", (int)getsid(pid));
printf("3: %d\n", (int)waitpid(pid, &status, WNOHANG));
}
// end pic_sys.c
gcc pic_sys.c -fPIC -o pic_sys
syscall.c: In function `getsid':
syscall.c:7: fixed or forbidden register 3 (bx) was spilled for class BREG.
This may be due to a compiler bug or to impossible asm
statements or clauses.
I tried listing it in the clobbers, to no avail. I'm a bit more familiar
with just gas, without all this C crap on top of it :) :)
btw, does it matter that I've split the "pushl %ebx / int 0x80" over two
separate asm lines? I wouldn't think so because of the volatile, but I'm
not 100% sure. The reason I did it was so that the pushl/popl would be
consistent with one percent sign; if it were inside the asm with "int
$0x80" then it'd need two percents.
Thanks! (diff attached, your thoughts?)
Chris Noe
(stiker@northlink.com)
--- /usr/src/linux-2.3.39/include/asm/unistd.h Wed Jan 12 18:21:12 2000
+++ linux/include/asm/unistd.h Sat Jan 15 11:29:32 2000
@@ -311,6 +311,90 @@
__syscall_return(type,__res); \
}
+/* PIC versions of the above (push/pop %ebx) */
+
+/* no need to save %ebx for syscall0, as it isn't used */
+#define _syscall0_pic(type,name) _syscall0(type,name)
+
+#define _syscall1_pic(type,name,type1,arg1) \
+type name(type1 arg1) \
+{ \
+long __res; \
+__asm__ volatile ("pushl %ebx"); \
+__asm__ volatile ("int $0x80" \
+ : "=a" (__res) \
+ : "0" (__NR_##name),"b" ((long)(arg1))); \
+__asm__ volatile ("popl %ebx"); \
+__syscall_return(type,__res); \
+}
+
+#define _syscall2_pic(type,name,type1,arg1,type2,arg2) \
+type name(type1 arg1,type2 arg2) \
+{ \
+long __res; \
+__asm__ volatile ("pushl %ebx"); \
+__asm__ volatile ("int $0x80" \
+ : "=a" (__res) \
+ : "0" (__NR_##name),"b" ((long)(arg1)),"c" ((long)(arg2))); \
+__asm__ volatile ("popl %ebx"); \
+__syscall_return(type,__res); \
+}
+
+#define _syscall3_pic(type,name,type1,arg1,type2,arg2,type3,arg3) \
+type name(type1 arg1,type2 arg2,type3 arg3) \
+{ \
+long __res; \
+__asm__ volatile ("pushl %ebx"); \
+__asm__ volatile ("int $0x80" \
+ : "=a" (__res) \
+ : "0" (__NR_##name),"b" ((long)(arg1)),"c" ((long)(arg2)), \
+ "d" ((long)(arg3))); \
+__asm__ volatile ("popl %ebx"); \
+__syscall_return(type,__res); \
+}
+
+#define _syscall4_pic(type,name,type1,arg1,type2,arg2,type3,arg3,type4,arg4) \
+type name (type1 arg1, type2 arg2, type3 arg3, type4 arg4) \
+{ \
+long __res; \
+__asm__ volatile ("pushl %ebx"); \
+__asm__ volatile ("int $0x80" \
+ : "=a" (__res) \
+ : "0" (__NR_##name),"b" ((long)(arg1)),"c" ((long)(arg2)), \
+ "d" ((long)(arg3)),"S" ((long)(arg4))); \
+__asm__ volatile ("popl %ebx"); \
+__syscall_return(type,__res); \
+}
+
+#define _syscall5_pic(type,name,type1,arg1,type2,arg2,type3,arg3,type4,arg4, \
+ type5,arg5) \
+type name (type1 arg1,type2 arg2,type3 arg3,type4 arg4,type5 arg5) \
+{ \
+long __res; \
+__asm__ volatile ("pushl %ebx"); \
+__asm__ volatile ("int $0x80" \
+ : "=a" (__res) \
+ : "0" (__NR_##name),"b" ((long)(arg1)),"c" ((long)(arg2)), \
+ "d" ((long)(arg3)),"S" ((long)(arg4)),"D" ((long)(arg5))); \
+__asm__ volatile ("popl %ebx"); \
+__syscall_return(type,__res); \
+}
+
+#define _syscall6_pic(type,name,type1,arg1,type2,arg2,type3,arg3,type4,arg4, \
+ type5,arg5,type6,arg6) \
+type name (type1 arg1,type2 arg2,type3 arg3,type4 arg4,type5 arg5,type6 arg6) \
+{ \
+long __res; \
+__asm__ volatile ("pushl %ebx"); \
+__asm__ volatile ("push %%ebp ; movl %%eax,%%ebp ; movl %1,%%eax ; int $0x80 ; pop %%ebp" \
+ : "=a" (__res) \
+ : "i" (__NR_##name),"b" ((long)(arg1)),"c" ((long)(arg2)), \
+ "d" ((long)(arg3)),"S" ((long)(arg4)),"D" ((long)(arg5)), \
+ "0" ((long)(arg6))); \
+__asm__ volatile ("popl %ebx"); \
+__syscall_return(type,__res); \
+}
+
#ifdef __KERNEL_SYSCALLS__
/*
-
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