ppc64: Preparation work for minimal register save/restore exception paths

arch/ppc64/kernel/entry.S

@@ -57,6 +57,9 @@ show_syscalls_task:
  * Handle a system call.
  */
 _GLOBAL(DoSyscall)
+	std	r3,ORIG_GPR3(r1)
+	li	r12,0
+	std	r12,RESULT(r1)
 	ld	r11,_CCR(r1)	/* Clear SO bit in CR */
 	lis	r10,0x1000
 	andc	r11,r11,r10

arch/ppc64/kernel/head.S

@@ -789,7 +789,6 @@ SystemCall_common:
 	beq+	HardwareInterrupt_entry
 1:
 #endif
-	std	r3,ORIG_GPR3(r1)
 #ifdef DO_SOFT_DISABLE
 	ld	r20,SOFTE(r1)
 #else
@@ -1119,12 +1118,6 @@ _GLOBAL(save_remaining_regs)
 	SAVE_4GPRS(16, r1)
 	SAVE_8GPRS(24, r1)
 
-	/*
-	 * Clear the RESULT field
-	 */
-	li	r22,0
-	std	r22,RESULT(r1)
-
 	/*
 	 * Test if from user state; result will be tested later
 	 */
@@ -1141,9 +1134,9 @@ _GLOBAL(save_remaining_regs)
 	 * If from user state, update THREAD.regs
 	 */
 	beq	2f			/* Modify THREAD.regs if from user */
-	addi	r24,r1,STACK_FRAME_OVERHEAD
+	addi	r23,r1,STACK_FRAME_OVERHEAD
 	ld	r22, PACACURRENT(r13)
-	std	r24,THREAD+PT_REGS(r22)
+	std	r23,THREAD+PT_REGS(r22)
 2:
 	SET_REG_TO_CONST(r22, MSR_KERNEL)
 

arch/ppc64/kernel/misc.S

@@ -443,26 +443,61 @@ _GLOBAL(cvt_df)
  *   kernel_thread(fn, arg, flags)
  */
 _GLOBAL(kernel_thread)
-	/* XXX fix this when we optimise syscall entry to not save volatiles */
-	mr	r6,r3		/* function */
-	mr	r7,r4		/* arg */
+	std	r29,-24(r1)
+	std	r30,-16(r1)
+	stdu	r1,-STACK_FRAME_OVERHEAD(r1)
+	mr	r29,r3
+	mr	r30,r4
 	ori	r3,r5,CLONE_VM	/* flags */
 	oris	r3,r3,(CLONE_UNTRACED>>16)
 	li	r4,0		/* new sp (unused) */
 	li	r0,__NR_clone
 	sc
 	cmpi	0,r3,0		/* parent or child? */
-	bnelr			/* return if parent */
+	bne	1f		/* return if parent */
 	li	r0,0
 	stdu	r0,-STACK_FRAME_OVERHEAD(r1)
-	ld	r2,8(r6)
-	ld	r6,0(r6)
-	mtlr	r6              /* fn addr in lr */
-	mr	r3,r7	        /* load arg and call fn */
+	ld	r2,8(r29)
+	ld	r29,0(r29)
+	mtlr	r29              /* fn addr in lr */
+	mr	r3,r30	        /* load arg and call fn */
 	blrl
 	li	r0,__NR_exit	/* exit after child exits */
         li	r3,0
 	sc
+1:	addi	r1,r1,STACK_FRAME_OVERHEAD	
+	ld	r29,-24(r1)
+	ld	r30,-16(r1)
+	blr
+
+	.section	".toc","aw"
+.SYSCALL_ERRNO:
+	.tc errno[TC],errno
+
+	.section	".text"
+	.align 3
+	
+#define SYSCALL(name) \
+_GLOBAL(name) \
+	li	r0,__NR_##name; \
+	sc; \
+	bnslr; \
+	ld	r4,.SYSCALL_ERRNO@toc(2); \
+	std	r3,0(r4); \
+	li	r3,-1; \
+	blr
+
+#define __NR__exit __NR_exit
+
+SYSCALL(setsid)
+SYSCALL(open)
+SYSCALL(read)
+SYSCALL(write)
+SYSCALL(lseek)
+SYSCALL(close)
+SYSCALL(dup)
+SYSCALL(execve)
+SYSCALL(waitpid)
 
 #ifdef CONFIG_BINFMT_ELF32
 /* Why isn't this a) automatic, b) written in 'C'? */	

include/asm-ppc64/unistd.h

@@ -242,6 +242,7 @@
 #define __NR_io_getevents	229
 #define __NR_io_submit		230
 #define __NR_io_cancel		231
+/* 223 + 224 currently unused */
 #define __NR_exit_group		234
 #define __NR_lookup_dcookie	235
 #define __NR_sys_epoll_create	236
@@ -249,178 +250,6 @@
 #define __NR_sys_epoll_wait	238
 #define __NR_remap_file_pages	239
 
-#define __NR(n)	#n
-
-
-#define __syscall_return(type) \
-	return (__sc_err & 0x10000000 ? errno = __sc_ret, __sc_ret = -1 : 0), \
-	       (type) __sc_ret
-
-#define __syscall_clobbers \
-	"r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12"
-
-#define _syscall0(type,name)						\
-type name(void)								\
-{									\
-	unsigned long __sc_ret, __sc_err;				\
-	{								\
-		register unsigned long __sc_0 __asm__ ("r0");		\
-		register unsigned long __sc_3 __asm__ ("r3");		\
-									\
-		__sc_0 = __NR_##name;					\
-		__asm__ __volatile__					\
-			("sc           \n\t"				\
-			 "mfcr %1      "				\
-			: "=&r" (__sc_3), "=&r" (__sc_0)		\
-			: "0"   (__sc_3), "1"   (__sc_0)		\
-			: __syscall_clobbers);				\
-		__sc_ret = __sc_3;					\
-		__sc_err = __sc_0;					\
-	}								\
-	__syscall_return (type);					\
-}
-
-#define _syscall1(type,name,type1,arg1)					\
-type name(type1 arg1)							\
-{									\
-	unsigned long __sc_ret, __sc_err;				\
-	{								\
-		register unsigned long __sc_0 __asm__ ("r0");		\
-		register unsigned long __sc_3 __asm__ ("r3");		\
-									\
-		__sc_3 = (unsigned long) (arg1);			\
-		__sc_0 = __NR_##name;					\
-		__asm__ __volatile__					\
-			("sc           \n\t"				\
-			 "mfcr %1      "				\
-			: "=&r" (__sc_3), "=&r" (__sc_0)		\
-			: "0"   (__sc_3), "1"   (__sc_0)		\
-			: __syscall_clobbers);				\
-		__sc_ret = __sc_3;					\
-		__sc_err = __sc_0;					\
-	}								\
-	__syscall_return (type);					\
-}
-
-#define _syscall2(type,name,type1,arg1,type2,arg2)			\
-type name(type1 arg1, type2 arg2)					\
-{									\
-	unsigned long __sc_ret, __sc_err;				\
-	{								\
-		register unsigned long __sc_0 __asm__ ("r0");		\
-		register unsigned long __sc_3 __asm__ ("r3");		\
-		register unsigned long __sc_4 __asm__ ("r4");		\
-									\
-		__sc_3 = (unsigned long) (arg1);			\
-		__sc_4 = (unsigned long) (arg2);			\
-		__sc_0 = __NR_##name;					\
-		__asm__ __volatile__					\
-			("sc           \n\t"				\
-			 "mfcr %1      "				\
-			: "=&r" (__sc_3), "=&r" (__sc_0)		\
-			: "0"   (__sc_3), "1"   (__sc_0),		\
-			  "r"   (__sc_4)				\
-			: __syscall_clobbers);				\
-		__sc_ret = __sc_3;					\
-		__sc_err = __sc_0;					\
-	}								\
-	__syscall_return (type);					\
-}
-
-#define _syscall3(type,name,type1,arg1,type2,arg2,type3,arg3)		\
-type name(type1 arg1, type2 arg2, type3 arg3)				\
-{									\
-	unsigned long __sc_ret, __sc_err;				\
-	{								\
-		register unsigned long __sc_0 __asm__ ("r0");		\
-		register unsigned long __sc_3 __asm__ ("r3");		\
-		register unsigned long __sc_4 __asm__ ("r4");		\
-		register unsigned long __sc_5 __asm__ ("r5");		\
-									\
-		__sc_3 = (unsigned long) (arg1);			\
-		__sc_4 = (unsigned long) (arg2);			\
-		__sc_5 = (unsigned long) (arg3);			\
-		__sc_0 = __NR_##name;					\
-		__asm__ __volatile__					\
-			("sc           \n\t"				\
-			 "mfcr %1      "				\
-			: "=&r" (__sc_3), "=&r" (__sc_0)		\
-			: "0"   (__sc_3), "1"   (__sc_0),		\
-			  "r"   (__sc_4),				\
-			  "r"   (__sc_5)				\
-			: __syscall_clobbers);				\
-		__sc_ret = __sc_3;					\
-		__sc_err = __sc_0;					\
-	}								\
-	__syscall_return (type);					\
-}
-
-#define _syscall4(type,name,type1,arg1,type2,arg2,type3,arg3,type4,arg4) \
-type name(type1 arg1, type2 arg2, type3 arg3, type4 arg4)		\
-{									\
-	unsigned long __sc_ret, __sc_err;				\
-	{								\
-		register unsigned long __sc_0 __asm__ ("r0");		\
-		register unsigned long __sc_3 __asm__ ("r3");		\
-		register unsigned long __sc_4 __asm__ ("r4");		\
-		register unsigned long __sc_5 __asm__ ("r5");		\
-		register unsigned long __sc_6 __asm__ ("r6");		\
-									\
-		__sc_3 = (unsigned long) (arg1);			\
-		__sc_4 = (unsigned long) (arg2);			\
-		__sc_5 = (unsigned long) (arg3);			\
-		__sc_6 = (unsigned long) (arg4);			\
-		__sc_0 = __NR_##name;					\
-		__asm__ __volatile__					\
-			("sc           \n\t"				\
-			 "mfcr %1      "				\
-			: "=&r" (__sc_3), "=&r" (__sc_0)		\
-			: "0"   (__sc_3), "1"   (__sc_0),		\
-			  "r"   (__sc_4),				\
-			  "r"   (__sc_5),				\
-			  "r"   (__sc_6)				\
-			: __syscall_clobbers);				\
-		__sc_ret = __sc_3;					\
-		__sc_err = __sc_0;					\
-	}								\
-	__syscall_return (type);					\
-}
-
-#define _syscall5(type,name,type1,arg1,type2,arg2,type3,arg3,type4,arg4,type5,arg5) \
-type name(type1 arg1, type2 arg2, type3 arg3, type4 arg4, type5 arg5)	\
-{									\
-	unsigned long __sc_ret, __sc_err;				\
-	{								\
-		register unsigned long __sc_0 __asm__ ("r0");		\
-		register unsigned long __sc_3 __asm__ ("r3");		\
-		register unsigned long __sc_4 __asm__ ("r4");		\
-		register unsigned long __sc_5 __asm__ ("r5");		\
-		register unsigned long __sc_6 __asm__ ("r6");		\
-		register unsigned long __sc_7 __asm__ ("r7");		\
-									\
-		__sc_3 = (unsigned long) (arg1);			\
-		__sc_4 = (unsigned long) (arg2);			\
-		__sc_5 = (unsigned long) (arg3);			\
-		__sc_6 = (unsigned long) (arg4);			\
-		__sc_7 = (unsigned long) (arg5);			\
-		__sc_0 = __NR_##name;					\
-		__asm__ __volatile__					\
-			("sc           \n\t"				\
-			 "mfcr %1      "				\
-			: "=&r" (__sc_3), "=&r" (__sc_0)		\
-			: "0"   (__sc_3), "1"   (__sc_0),		\
-			  "r"   (__sc_4),				\
-			  "r"   (__sc_5),				\
-			  "r"   (__sc_6),				\
-			  "r"   (__sc_7)				\
-			: __syscall_clobbers);				\
-		__sc_ret = __sc_3;					\
-		__sc_err = __sc_0;					\
-	}								\
-	__syscall_return (type);					\
-}
-
-
 #ifdef __KERNEL_SYSCALLS__
 
 /*
@@ -434,17 +263,15 @@ type name(type1 arg1, type2 arg2, type3 arg3, type4 arg4, type5 arg5)	\
 /*
  * System call prototypes.
  */
-#define __NR__exit __NR_exit
-static inline _syscall0(pid_t,setsid)
-static inline _syscall3(int,write,int,fd,const char *,buf,off_t,count)
-static inline _syscall3(int,read,int,fd,char *,buf,off_t,count)
-static inline _syscall3(off_t,lseek,int,fd,off_t,offset,int,count)
-static inline _syscall1(int,dup,int,fd)
-static inline _syscall3(int,execve,const char *,file,char **,argv,char **,envp)
-static inline _syscall3(int,open,const char *,file,int,flag,int,mode)
-static inline _syscall1(int,close,int,fd)
-static inline _syscall1(int,_exit,int,exitcode)
-static inline _syscall3(pid_t,waitpid,pid_t,pid,int *,wait_stat,int,options)
+extern pid_t setsid(void);
+extern int write(int fd, const char *buf, off_t count);
+extern int read(int fd, char *buf, off_t count);
+extern off_t lseek(int fd, off_t offset, int count);
+extern int dup(int fd);
+extern int execve(const char *file, char **argv, char **envp);
+extern int open(const char *file, int flag, int mode);
+extern int close(int fd);
+extern pid_t waitpid(pid_t pid, int *wait_stat, int options);
 
 #endif /* __KERNEL_SYSCALLS__ */