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x86/nmi: Fix section mismatch warnings on 32-bit

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It was reported that compiling for 32-bit caused a bunch of
section mismatch warnings:

 VDSOSYM arch/x86/vdso/vdso32-syms.lds
  LD      arch/x86/vdso/built-in.o
  LD      arch/x86/built-in.o

 WARNING: arch/x86/built-in.o(.data+0x5af0): Section mismatch in
 reference from the variable test_nmi_ipi_callback_na.10451 to
 the function .init.text:test_nmi_ipi_callback() [...]

 WARNING: arch/x86/built-in.o(.data+0x5b04): Section mismatch in
 reference from the variable nmi_unk_cb_na.10399 to the function
 .init.text:nmi_unk_cb() The variable nmi_unk_cb_na.10399
 references the function __init nmi_unk_cb() [...]

Both of these are attributed to the internal representation of
the nmiaction struct created during register_nmi_handler.  The
reason for this is that those structs are not defined in the
init section whereas the rest of the code in nmi_selftest.c is.

To resolve this, I created a new #define,
register_nmi_handler_initonly, that tags the struct as
__initdata to resolve the mismatch.  This #define should only be
used in rare situations where the register/unregister is called
during init of the kernel.

Big thanks to Jan Beulich for decoding this for me as I didn't
have a clue what was going on.

Reported-by: Witold Baryluk <baryluk@smp.if.uj.edu.pl>
Tested-by: Witold Baryluk <baryluk@smp.if.uj.edu.pl>
Cc: Jan Beulich <JBeulich@suse.com>
Signed-off-by: Don Zickus <dzickus@redhat.com>
Link: http://lkml.kernel.org/r/1338991542-23000-1-git-send-email-dzickus@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Don Zickus 2012-06-06 10:05:42 -04:00 • committed by Ingo Molnar
commit eeaaa96a3a
2 changed files with 16 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

14
arch/x86/include/asm/nmi.h
View file

@ -54,6 +54,20 @@ struct nmiaction {
__register_nmi_handler((t), &fn##_na); \
})
/*
* For special handlers that register/unregister in the
* init section only. This should be considered rare.
*/
#define register_nmi_handler_initonly(t, fn, fg, n) \
({ \
static struct nmiaction fn##_na __initdata = { \
.handler = (fn), \
.name = (n), \
.flags = (fg), \
}; \
__register_nmi_handler((t), &fn##_na); \
})
int __register_nmi_handler(unsigned int, struct nmiaction *);
void unregister_nmi_handler(unsigned int, const char *);

4
arch/x86/kernel/nmi_selftest.c
View file

@ -42,7 +42,7 @@ static int __init nmi_unk_cb(unsigned int val, struct pt_regs *regs)
static void __init init_nmi_testsuite(void)
{
/* trap all the unknown NMIs we may generate */
register_nmi_handler(NMI_UNKNOWN, nmi_unk_cb, 0, "nmi_selftest_unk");
register_nmi_handler_initonly(NMI_UNKNOWN, nmi_unk_cb, 0, "nmi_selftest_unk");
}
static void __init cleanup_nmi_testsuite(void)
@ -64,7 +64,7 @@ static void __init test_nmi_ipi(struct cpumask *mask)
{
unsigned long timeout;
if (register_nmi_handler(NMI_LOCAL, test_nmi_ipi_callback,
if (register_nmi_handler_initonly(NMI_LOCAL, test_nmi_ipi_callback,
NMI_FLAG_FIRST, "nmi_selftest")) {
nmi_fail = FAILURE;
return;