Hi Ian, I needed the following patch to avoid lots of these warnings:
elf.c:238: warning: pointer of type `void *'' used in arithmetic
Fix void* arithmetic warnings.
Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
diff -r 030a041bbe90 xen/common/elf.c
--- a/xen/common/elf.c Tue Aug 29 06:53:58 2006 -0400
+++ b/xen/common/elf.c Tue Aug 29 15:22:26 2006 -0500
@@ -102,9 +102,9 @@ static unsigned long long xen_guest_nume
/*
* Interface to the Xen ELF notes.
*/
-#define ELFNOTE_NAME(_n_) ((void*)(_n_) + sizeof(*(_n_)))
-#define ELFNOTE_DESC(_n_) (ELFNOTE_NAME(_n_) + (((_n_)->namesz+3)&~3))
-#define ELFNOTE_NEXT(_n_) (ELFNOTE_DESC(_n_) + (((_n_)->descsz+3)&~3))
+#define ELFNOTE_NAME(_n_) ((void*)((char*)(_n_) + sizeof(*(_n_))))
+#define ELFNOTE_DESC(_n_) (((void*)((char*)ELFNOTE_NAME(_n_) +
(((_n_)->namesz+3)&~3))))
+#define ELFNOTE_NEXT(_n_) (((void*)((char*)ELFNOTE_DESC(_n_) +
(((_n_)->descsz+3)&~3))))
static int is_xen_elfnote_section(const char *image, Elf_Shdr *shdr)
{
@@ -235,9 +235,9 @@ int parseelfimage(struct domain_setup_in
shdr = (Elf_Shdr *)(image + ehdr->e_shoff +
(h*ehdr->e_shentsize));
if ( !is_xen_elfnote_section(image, shdr) )
continue;
- dsi->__elfnote_section = (void *)image + shdr->sh_offset;
+ dsi->__elfnote_section = (char *)image + shdr->sh_offset;
dsi->__elfnote_section_end - (void *)image +
shdr->sh_offset + shdr->sh_size;
+ (char *)image + shdr->sh_offset + shdr->sh_size;
break;
}
--
Hollis Blanchard
IBM Linux Technology Center
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Hollis Blanchard wrote: [Tue Aug 29 2006, 04:24:48PM EDT]> +#define ELFNOTE_NAME(_n_) ((void*)((char*)(_n_) + sizeof(*(_n_)))) > +#define ELFNOTE_DESC(_n_) (((void*)((char*)ELFNOTE_NAME(_n_) + (((_n_)->namesz+3)&~3)))) > +#define ELFNOTE_NEXT(_n_) (((void*)((char*)ELFNOTE_DESC(_n_) + (((_n_)->descsz+3)&~3))))Too many parens on the latter two? I think this is the same: #define ELFNOTE_NAME(_n_) ((void*)((char*)(_n_) + sizeof(*(_n_)))) #define ELFNOTE_DESC(_n_) ((void*)((char*)ELFNOTE_NAME(_n_) + (((_n_)->namesz+3)&~3))) #define ELFNOTE_NEXT(_n_) ((void*)((char*)ELFNOTE_DESC(_n_) + (((_n_)->descsz+3)&~3))) Aron _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On Tue, 2006-08-29 at 15:24 -0500, Hollis Blanchard wrote:> Hi Ian, I needed the following patch to avoid lots of these warnings: > elf.c:238: warning: pointer of type `void *'' used in arithmetic > > Fix void* arithmetic warnings. > Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>Looks like PPC is the only arch using -Wpointer-arith, is there a reason for that? Ian. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On Tue, 2006-08-29 at 22:06 +0100, Ian Campbell wrote:> On Tue, 2006-08-29 at 15:24 -0500, Hollis Blanchard wrote: > > Hi Ian, I needed the following patch to avoid lots of these warnings: > > elf.c:238: warning: pointer of type `void *'' used in arithmetic > > > > Fix void* arithmetic warnings. > > Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com> > > Looks like PPC is the only arch using -Wpointer-arith, is there a reason > for that?Is there are reason the other architectures *aren''t* using it? We have some extra warnings enabled because they''ve helped us in the past (such as -Wshadow). Given that we''re just playing janitor for everyone else''s code though, I think we''re about to abandon that one. -- Hollis Blanchard IBM Linux Technology Center _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Hollis Blanchard wrote:> On Tue, 2006-08-29 at 22:06 +0100, Ian Campbell wrote: >> On Tue, 2006-08-29 at 15:24 -0500, Hollis Blanchard wrote: >>> Hi Ian, I needed the following patch to avoid lots of these warnings: >>> elf.c:238: warning: pointer of type `void *'' used in arithmetic >>> >>> Fix void* arithmetic warnings. >>> Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com> >> Looks like PPC is the only arch using -Wpointer-arith, is there a reason >> for that? > > Is there are reason the other architectures *aren''t* using it? > > We have some extra warnings enabled because they''ve helped us in the > past (such as -Wshadow). Given that we''re just playing janitor for > everyone else''s code though, I think we''re about to abandon that one.Pointer arith is quite valid on void pointers, when using gcc and most other modern compilers. Point of fact, any Linux kernel-related code REQUIRES that void* arith be valid, and not cause warnings. As we see from your patch, all a cast to char* does is complicate the code, for zero gain. Jeff _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
>-#define ELFNOTE_NAME(_n_) ((void*)(_n_) + sizeof(*(_n_))) >-#define ELFNOTE_DESC(_n_) (ELFNOTE_NAME(_n_) + (((_n_)->namesz+3)&~3)) >-#define ELFNOTE_NEXT(_n_) (ELFNOTE_DESC(_n_) + (((_n_)->descsz+3)&~3)) >+#define ELFNOTE_NAME(_n_) ((void*)((char*)(_n_) + sizeof(*(_n_)))) >+#define ELFNOTE_DESC(_n_) (((void*)((char*)ELFNOTE_NAME(_n_) + (((_n_)->namesz+3)&~3)))) >+#define ELFNOTE_NEXT(_n_) (((void*)((char*)ELFNOTE_DESC(_n_) + (((_n_)->descsz+3)&~3))))This seems to complicate it a little too much, eg it would seem that this #define ELFNOTE_NAME(_n_) ((char *)(_n_) + sizeof(*(_n_))) #define ELFNOTE_DESC(_n_) (ELFNOTE_NAME(_n_) + (((_n_)->namesz+3)&~3)) #define ELFNOTE_NEXT(_n_) ((Elf_Note *)(ELFNOTE_DESC(_n_) + (((_n_)->descsz+3)&~3))) would also do, and would even allow dropping an odd cast in the return statement of xen_elfnote_string(). Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On 29/8/06 10:18 pm, "Hollis Blanchard" <hollisb@us.ibm.com> wrote:>> Looks like PPC is the only arch using -Wpointer-arith, is there a reason >> for that? > > Is there are reason the other architectures *aren''t* using it? > > We have some extra warnings enabled because they''ve helped us in the > past (such as -Wshadow). Given that we''re just playing janitor for > everyone else''s code though, I think we''re about to abandon that one.We have code borrowed from Linux that doesn''t like -Wpointer-arith very much, so we took the pragmatic path here. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel