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SubjectRe: [PATCH] x86,nmi: Fix section mismatch warnings on 32-bit
On 06-06 10:05, Don Zickus wrote:
> 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()
> The variable test_nmi_ipi_callback_na.10451 references
> the function __init test_nmi_ipi_callback()
> If the reference is valid then annotate the
> variable with __init* or __refdata (see linux/init.h) or name the variable:
> *_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console
>
> 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()
> If the reference is valid then annotate the
> variable with __init* or __refdata (see linux/init.h) or name the variable:
> *_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console
>
> 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>
> Cc: Jan Beulich <JBeulich@suse.com>
> Signed-off-by: Don Zickus <dzickus@redhat.com>
> ---
> arch/x86/include/asm/nmi.h | 14 ++++++++++++++
> arch/x86/kernel/nmi_selftest.c | 4 ++--
> 2 files changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h
> index 0e3793b..dc580c4 100644
> --- a/arch/x86/include/asm/nmi.h
> +++ b/arch/x86/include/asm/nmi.h
> @@ -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 *);
> diff --git a/arch/x86/kernel/nmi_selftest.c b/arch/x86/kernel/nmi_selftest.c
> index e31bf8d..149b8d9 100644
> --- a/arch/x86/kernel/nmi_selftest.c
> +++ b/arch/x86/kernel/nmi_selftest.c
> @@ -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;
> --
> 1.7.7.6
>

Works for me.

Tested-by: Witold Baryluk <baryluk@smp.if.uj.edu.pl>


--
Witold Baryluk


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