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[05/17] lto: Handle LTO common symbols in module loader

Message ID 1391846481-31491-5-git-send-email-ak@linux.intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Andi Kleen Feb. 8, 2014, 8:01 a.m. UTC 
From: Joe Mario <jmario@redhat.com>

Here is the workaround I made for having the kernel not reject modules
built with -flto.  The clean solution would be to get the compiler to not
emit the symbol.  Or if it has to emit the symbol, then emit it as
initialized data but put it into a comdat/linkonce section.

Minor tweaks by AK over Joe's patch.

Cc: rusty@rustcorp.com.au
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 kernel/module.c | 4 ++++
 1 file changed, 4 insertions(+)

Comments

Rusty Russell Feb. 12, 2014, 1:04 a.m. UTC | #1 
Andi Kleen <ak@linux.intel.com> writes:
> From: Joe Mario <jmario@redhat.com>
>
> Here is the workaround I made for having the kernel not reject modules
> built with -flto.  The clean solution would be to get the compiler to not
> emit the symbol.  Or if it has to emit the symbol, then emit it as
> initialized data but put it into a comdat/linkonce section.
>
> Minor tweaks by AK over Joe's patch.

Patch is fine, but what's with the comment?

>  		switch (sym[i].st_shndx) {
>  		case SHN_COMMON:
> +			/* Ignore common symbols */
> +			if (!strncmp(name, "__gnu_lto", 9))
> +				break;
> +

You mean, "/* Ignore symbols from -flto */"?

Other than that, I'm happy for this to go via some other tree:

Acked-by: Rusty Russell <rusty@rustcorp.com.au>

Thanks,
Rusty.
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diff mbox

Patch

diff --git a/kernel/module.c b/kernel/module.c
index d24fcf2..b99e801 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1948,6 +1948,10 @@  static int simplify_symbols(struct module *mod, const struct load_info *info)
 
 		switch (sym[i].st_shndx) {
 		case SHN_COMMON:
+			/* Ignore common symbols */
+			if (!strncmp(name, "__gnu_lto", 9))
+				break;
+
 			/* We compiled with -fno-common.  These are not
 			   supposed to happen.  */
 			pr_debug("Common symbol: %s\n", name);