Make do_execve() take a const filename pointer

Make do_execve() take a const filename pointer so that kernel_execve() compiles
correctly on ARM:

arch/arm/kernel/sys_arm.c:88: warning: passing argument 1 of 'do_execve' discards qualifiers from pointer target type

This also requires the argv and envp arguments to be consted twice, once for
the pointer array and once for the strings the array points to.  This is
because do_execve() passes a pointer to the filename (now const) to
copy_strings_kernel().  A simpler alternative would be to cast the filename
pointer in do_execve() when it's passed to copy_strings_kernel().

do_execve() may not change any of the strings it is passed as part of the argv
or envp lists as they are some of them in .rodata, so marking these strings as
const should be fine.

Further kernel_execve() and sys_execve() need to be changed to match.

This has been test built on x86_64, frv, arm and mips.

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 12 insertions, 7 deletions

diff --git a/arch/sh/kernel/process_32.c b/arch/sh/kernel/process_32.c
index 0529819..762a139 100644
--- a/arch/sh/kernel/process_32.c
+++ b/arch/sh/kernel/process_32.c
@@ -296,9 +296,10 @@ asmlinkage int sys_vfork(unsigned long r4, unsigned long r5,
 /*
  * sys_execve() executes a new program.
  */
-asmlinkage int sys_execve(char __user *ufilename, char __user * __user *uargv,
-			  char __user * __user *uenvp, unsigned long r7,
-			  struct pt_regs __regs)
+asmlinkage int sys_execve(const char __user *ufilename,
+			  const char __user *const __user *uargv,
+			  const char __user *const __user *uenvp,
+			  unsigned long r7, struct pt_regs __regs)
 {
 	struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
 	int error;
diff --git a/arch/sh/kernel/process_64.c b/arch/sh/kernel/process_64.c
index 68d128d..210c1ca 100644
--- a/arch/sh/kernel/process_64.c
+++ b/arch/sh/kernel/process_64.c
@@ -497,8 +497,8 @@ asmlinkage int sys_execve(const char *ufilename, char **uargv,
 		goto out;
 
 	error = do_execve(filename,
-			  (char __user * __user *)uargv,
-			  (char __user * __user *)uenvp,
+			  (const char __user *const __user *)uargv,
+			  (const char __user *const __user *)uenvp,
 			  pregs);
 	putname(filename);
 out:
diff --git a/arch/sh/kernel/sys_sh32.c b/arch/sh/kernel/sys_sh32.c
index eb68bfd..f56b6fe5 100644
--- a/arch/sh/kernel/sys_sh32.c
+++ b/arch/sh/kernel/sys_sh32.c
@@ -71,7 +71,9 @@ asmlinkage int sys_fadvise64_64_wrapper(int fd, u32 offset0, u32 offset1,
  * 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, char *const argv[], char *const envp[])
+int kernel_execve(const char *filename,
+		  const char *const argv[],
+		  const char *const envp[])
 {
 	register long __sc0 __asm__ ("r3") = __NR_execve;
 	register long __sc4 __asm__ ("r4") = (long) filename;
diff --git a/arch/sh/kernel/sys_sh64.c b/arch/sh/kernel/sys_sh64.c
index 2872357..c5a38c4 100644
--- a/arch/sh/kernel/sys_sh64.c
+++ b/arch/sh/kernel/sys_sh64.c
@@ -33,7 +33,9 @@
  * 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, char *const argv[], char *const envp[])
+int kernel_execve(const char *filename,
+		  const char *const argv[],
+		  const char *const envp[])
 {
 	register unsigned long __sc0 __asm__ ("r9") = ((0x13 << 16) | __NR_execve);
 	register unsigned long __sc2 __asm__ ("r2") = (unsigned long) filename;