2012-06-06 14:06:08

by Don Zickus

Subject: [PATCH] x86,nmi: Fix section mismatch warnings on 32-bit

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 <[email protected]>
Cc: Jan Beulich <[email protected]>
Signed-off-by: Don Zickus <[email protected]>
---
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

2012-06-06 21:22:10

by Witold Baryluk

Subject: Re: [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 <[email protected]>
> Cc: Jan Beulich <[email protected]>
> Signed-off-by: Don Zickus <[email protected]>
> ---
> 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 <[email protected]>


--
Witold Baryluk

2012-06-08 14:57:33

by Don Zickus

Subject: [tip:x86/urgent] x86/nmi: Fix section mismatch warnings on 32-bit

Commit-ID: eeaaa96a3a2134a174100afd129bb0891d05f4b2
Gitweb: http://git.kernel.org/tip/eeaaa96a3a2134a174100afd129bb0891d05f4b2
Author: Don Zickus <[email protected]>
AuthorDate: Wed, 6 Jun 2012 10:05:42 -0400
Committer: Ingo Molnar <[email protected]>
CommitDate: Fri, 8 Jun 2012 12:19:27 +0200

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

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 <[email protected]>
Tested-by: Witold Baryluk <[email protected]>
Cc: Jan Beulich <[email protected]>
Signed-off-by: Don Zickus <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
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;