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>

2 files changed, 7 insertions, 3 deletions

diff --git a/arch/cris/arch-v10/kernel/process.c b/arch/cris/arch-v10/kernel/process.c
index 93f0f64b1326..9a57db6907f5 100644
--- a/arch/cris/arch-v10/kernel/process.c
+++ b/arch/cris/arch-v10/kernel/process.c
@@ -204,7 +204,9 @@ asmlinkage int sys_vfork(long r10, long r11, long r12, long r13, long mof, long
 /*
  * sys_execve() executes a new program.
  */
-asmlinkage int sys_execve(const char *fname, char **argv, char **envp,
+asmlinkage int sys_execve(const char *fname,
+                          const char *const *argv,
+                          const char *const *envp,
                           long r13, long mof, long srp, 
                           struct pt_regs *regs)
 {
diff --git a/arch/cris/arch-v32/kernel/process.c b/arch/cris/arch-v32/kernel/process.c
index 2661a9529d70..562f84718906 100644
--- a/arch/cris/arch-v32/kernel/process.c
+++ b/arch/cris/arch-v32/kernel/process.c
@@ -218,8 +218,10 @@ sys_vfork(long r10, long r11, long r12, long r13, long mof, long srp,
 
 /* sys_execve() executes a new program. */
 asmlinkage int
-sys_execve(const char *fname, char **argv, char **envp, long r13, long mof, long srp,
-        struct pt_regs *regs)
+sys_execve(const char *fname,
+           const char *const *argv,
+           const char *const *envp, long r13, long mof, long srp,
+           struct pt_regs *regs)
 {
         int error;
         char *filename;