sparc32: switch to generic kernel_execve()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/sparc/Kconfig

@@ -41,6 +41,7 @@ config SPARC
 	select GENERIC_STRNLEN_USER
 	select MODULES_USE_ELF_RELA
 	select GENERIC_KERNEL_THREAD
+	select GENERIC_KERNEL_EXECVE
 
 config SPARC32
 	def_bool !64BIT
@@ -75,7 +76,6 @@ config SPARC64
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select HAVE_C_RECORDMCOUNT
 	select NO_BOOTMEM
-	select GENERIC_KERNEL_EXECVE
 
 config ARCH_DEFCONFIG
 	string

arch/sparc/include/asm/ptrace.h

@@ -90,6 +90,9 @@ static inline bool pt_regs_clear_syscall(struct pt_regs *regs)
 #define arch_ptrace_stop(exit_code, info) \
 	synchronize_user_stack()
 
+#define current_pt_regs() \
+	((struct pt_regs *)((unsigned long)current_thread_info() + THREAD_SIZE) - 1)
+
 #define user_mode(regs) (!((regs)->psr & PSR_PS))
 #define instruction_pointer(regs) ((regs)->pc)
 #define user_stack_pointer(regs) ((regs)->u_regs[UREG_FP])

arch/sparc/kernel/entry.S

@@ -990,8 +990,15 @@ ret_from_kernel_thread:
 	ld	[%sp + STACKFRAME_SZ + PT_G1], %l0
 	call	%l0
 	 ld	[%sp + STACKFRAME_SZ + PT_G2], %o0
-	call	do_exit	/* won't return */
-	 clr	%o0
+	rd	%psr, %l1
+	ld	[%sp + STACKFRAME_SZ + PT_PSR], %l0
+	andn	%l0, PSR_CWP, %l0
+	nop
+	and	%l1, PSR_CWP, %l1
+	or	%l0, %l1, %l0
+	st	%l0, [%sp + STACKFRAME_SZ + PT_PSR]
+	b	ret_sys_call
+	 mov	0, %o0
 
 	/* Linux native system calls enter here... */
 	.align	4

arch/sparc/kernel/sys_sparc_32.c

@@ -258,27 +258,3 @@ out:
 	up_read(&uts_sem);
 	return err;
 }
-
-/*
- * Do a system call from kernel instead of calling sys_execve so we
- * end up with proper pt_regs.
- */
-int kernel_execve(const char *filename,
-		  const char *const argv[],
-		  const char *const envp[])
-{
-	long __res;
-	register long __g1 __asm__ ("g1") = __NR_execve;
-	register long __o0 __asm__ ("o0") = (long)(filename);
-	register long __o1 __asm__ ("o1") = (long)(argv);
-	register long __o2 __asm__ ("o2") = (long)(envp);
-	asm volatile ("t 0x10\n\t"
-		      "bcc 1f\n\t"
-		      "mov %%o0, %0\n\t"
-		      "sub %%g0, %%o0, %0\n\t"
-		      "1:\n\t"
-		      : "=r" (__res), "=&r" (__o0)
-		      : "1" (__o0), "r" (__o1), "r" (__o2), "r" (__g1)
-		      : "cc");
-	return __res;
-}