Messages in this thread Patch in this message | | | Date | Wed, 24 Apr 2013 11:13:53 +0100 | From | James Hogan <> | Subject | Re: [PATCH] x86_32: Fix module version table mismatch. |
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On 24/04/13 02:00, H. Peter Anvin wrote: > On 04/23/2013 05:52 PM, H. Peter Anvin wrote: >> On 04/23/2013 05:40 AM, Tetsuo Handa wrote: >>> Commit a4b6a77b "module: fix symbol versioning with symbol prefixes" broke >>> loading of net/ipv6/ipv6.ko built with CONFIG_MODVERSIONS=y for x86_32. >> >> This really does seem to be the offending commit, although I'm still >> confused how the heck that is possible. >> > > OK, now I grok. > > The bug is the use of VMLINUX_SYMBOL_STR(%s) which expands at the time > the output of modpost is compiled. However, VMLINUX_SYMBOL_STR() unlike > __VMLINUX_SYMBOL_STR() does macro expansion on its argument, which is > actively wrong here.
Yes, nasty bug there (sorry!)
> I think the choice is either to change this to __VMLINUX_SYMBOL_STR() or > re-introduce CONFIG_SYMBOL_PREFIX (or its equivalent) so that modprobe > can emit it at compile time
Using __VMLINUX_SYMBOL_STR looks like the correct solution to me.
> (assuming there even should *be* a prefix on > the symbol here, i.e. that the compiler won't add it.)
[__]VMLINUX_SYMBOL_STR expands to a string (e.g. "_" "memcmp" or just "memcmp") so the compiler won't touch it.
> > Either way -- James, Rusty, this is in your court.
How does the patch below look? I presume this is preferred over making VMLINUX_SYMBOL_STR non-argument-expanding?
Thanks James
Subject: [PATCH 1/1] modpost: fix unwanted VMLINUX_SYMBOL_STR expansion
Commit a4b6a77b77ba4f526392612c2365797fab956014 ("module: fix symbol versioning with symbol prefixes") broke the MODVERSIONS loading of any module using memcmp (e.g. ipv6) on x86_32, as it's defined to __builtin_memcmp which is expanded by VMLINUX_SYMBOL_STR. Use __VMLINUX_SYMBOL_STR instead which doesn't expand the argument.
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: H. Peter Anvin <hpa@zytor.com> --- scripts/mod/modpost.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 1f90961..a4be8e1 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1957,7 +1957,7 @@ static int add_versions(struct buffer *b, struct module *mod) s->name, mod->name); continue; } - buf_printf(b, "\t{ %#8x, VMLINUX_SYMBOL_STR(%s) },\n", + buf_printf(b, "\t{ %#8x, __VMLINUX_SYMBOL_STR(%s) },\n", s->crc, s->name); } -- 1.8.1.2
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