Due to commit dc326fca2b64 (x86, cpu: Clean up and unify the NOP selection infrastructure), we get the following warning:
arch/x86/kernel/ftrace.c: In function ‘ftrace_make_nop’:
arch/x86/kernel/ftrace.c:308:6: warning: assignment discards qualifiers from pointer target type
arch/x86/kernel/ftrace.c: In function ‘ftrace_make_call’:
arch/x86/kernel/ftrace.c:318:6: warning: assignment discards qualifiers from pointer target type
ftrace_nop_replace() now returns const unsigned char *, so change its associated function/variable to its compatible type to keep compiler clam.
Signed-off-by: Rakib Mullick <[email protected]>
---
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 0ba15a6..d2d82cf 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -266,8 +266,8 @@ static const unsigned char *ftrace_nop_replace(void)
}
static int
-ftrace_modify_code(unsigned long ip, unsigned char *old_code,
- unsigned char *new_code)
+ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
+ unsigned const char *new_code)
{
unsigned char replaced[MCOUNT_INSN_SIZE];
@@ -290,7 +290,7 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
return -EINVAL;
/* replace the text with the new text */
- if (do_ftrace_mod_code(ip, new_code))
+ if (do_ftrace_mod_code(ip, (void *)new_code))
return -EPERM;
sync_core();
@@ -301,7 +301,7 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
int ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
{
- unsigned char *new, *old;
+ unsigned const char *new, *old;
unsigned long ip = rec->ip;
old = ftrace_call_replace(ip, addr);
@@ -312,7 +312,7 @@ int ftrace_make_nop(struct module *mod,
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
- unsigned char *new, *old;
+ unsigned const char *new, *old;
unsigned long ip = rec->ip;
old = ftrace_nop_replace();
On Thu, 2011-05-12 at 23:33 +0600, Rakib Mullick wrote:
> Due to commit dc326fca2b64 (x86, cpu: Clean up and unify the NOP selection infrastructure), we get the following warning:
>
> arch/x86/kernel/ftrace.c: In function ‘ftrace_make_nop’:
> arch/x86/kernel/ftrace.c:308:6: warning: assignment discards qualifiers from pointer target type
> arch/x86/kernel/ftrace.c: In function ‘ftrace_make_call’:
> arch/x86/kernel/ftrace.c:318:6: warning: assignment discards qualifiers from pointer target type
>
> ftrace_nop_replace() now returns const unsigned char *, so change its associated function/variable to its compatible type to keep compiler clam.
>
>
> Signed-off-by: Rakib Mullick <[email protected]>
> ---
>
> diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
> index 0ba15a6..d2d82cf 100644
> --- a/arch/x86/kernel/ftrace.c
> +++ b/arch/x86/kernel/ftrace.c
> @@ -266,8 +266,8 @@ static const unsigned char *ftrace_nop_replace(void)
> }
>
> static int
> -ftrace_modify_code(unsigned long ip, unsigned char *old_code,
> - unsigned char *new_code)
> +ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
> + unsigned const char *new_code)
> {
> unsigned char replaced[MCOUNT_INSN_SIZE];
>
> @@ -290,7 +290,7 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
> return -EINVAL;
>
> /* replace the text with the new text */
> - if (do_ftrace_mod_code(ip, new_code))
> + if (do_ftrace_mod_code(ip, (void *)new_code))
Instead of typecasting, why not make new_code const void *?
This would probably trickle down to change __probe_kernel_write() which
would not be a bad thing.
-- Steve
> return -EPERM;
>
> sync_core();
> @@ -301,7 +301,7 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
> int ftrace_make_nop(struct module *mod,
> struct dyn_ftrace *rec, unsigned long addr)
> {
> - unsigned char *new, *old;
> + unsigned const char *new, *old;
> unsigned long ip = rec->ip;
>
> old = ftrace_call_replace(ip, addr);
> @@ -312,7 +312,7 @@ int ftrace_make_nop(struct module *mod,
>
> int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
> {
> - unsigned char *new, *old;
> + unsigned const char *new, *old;
> unsigned long ip = rec->ip;
>
> old = ftrace_nop_replace();
>
On Tue, 2011-05-17 at 23:11 +0600, Rakib Mullick wrote:
>
BTW, You have a weird email client. Causes lots of weird whitespace
> There are other places where they depend on __probe_kernel_write(), it
> might require to change all __probe_kernel_write() callers.
Why would callers of __probe_kernel_write() need to be changed? You can
pass any pointer into a const void*. You just can't do it the other way
around.
-- Steve
>
>
On Wed, 2011-05-18 at 11:02 +0600, Rakib Mullick wrote:
>
>
> Cause, __probe_kernel_write() currently takes void * as its parameter.
> That means all the users of __probe_kernel_write() currently passes
> void *. If we change __probe_kernel_write's parameter ( src) from void
> * to const void * , then all the callers also needs to do that. Isn't
> it?
No.
Look at __probe_kernel_write() itself. It calls
__copy_to_user_in_atomic() which takes const void *src, where we pass in
void *src. That __probe_kernel_write() having void *src is actually a
bug.
Make that a separate patch, or maybe I'll just do it.
-- Steve