[PATCH] powerpc: fix function annotations to avoid section mismatch warnings with gcc-10

[PATCH] powerpc: fix function annotations to avoid section mismatch warnings with gcc-10

[Vladis Dronov]

Certain warnings are emitted for powerpc code when building with a gcc-10
toolset:

    WARNING: modpost: vmlinux.o(.text.unlikely+0x377c): Section mismatch in
    reference from the function remove_pmd_table() to the function
    .meminit.text:split_kernel_mapping()
    The function remove_pmd_table() references
    the function __meminit split_kernel_mapping().
    This is often because remove_pmd_table lacks a __meminit
    annotation or the annotation of split_kernel_mapping is wrong.

Add the appropriate __init and __meminit annotations to make modpost not
complain. In all the cases there are just a single callsite from another
__init or __meminit function:

__meminit remove_pagetable() -> remove_pud_table() -> remove_pmd_table()
__init prom_init() -> setup_secure_guest()
__init xive_spapr_init() -> xive_spapr_disabled()

Signed-off-by: Vladis Dronov <vdronov@redhat.com>
---
 arch/powerpc/kernel/prom_init.c          | 4 ++--
 arch/powerpc/mm/book3s64/radix_pgtable.c | 4 ++--
 arch/powerpc/sysdev/xive/spapr.c         | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index 90c604d00b7d..f6ca7f450361 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -3262,7 +3262,7 @@ static int enter_secure_mode(unsigned long kbase, unsigned long fdt)
 /*
  * Call the Ultravisor to transfer us to secure memory if we have an ESM blob.
  */
-static void setup_secure_guest(unsigned long kbase, unsigned long fdt)
+static void __init setup_secure_guest(unsigned long kbase, unsigned long fdt)
 {
 	int ret;
 
@@ -3292,7 +3292,7 @@ static void setup_secure_guest(unsigned long kbase, unsigned long fdt)
 	}
 }
 #else
-static void setup_secure_guest(unsigned long kbase, unsigned long fdt)
+static void __init setup_secure_guest(unsigned long kbase, unsigned long fdt)
 {
 }
 #endif /* CONFIG_PPC_SVM */
diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
index bb00e0cba119..b868c07110e3 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -800,7 +800,7 @@ static void __meminit split_kernel_mapping(unsigned long addr, unsigned long end
 	pte_clear(&init_mm, addr, pte);
 }
 
-static void remove_pmd_table(pmd_t *pmd_start, unsigned long addr,
+static void __meminit remove_pmd_table(pmd_t *pmd_start, unsigned long addr,
 			     unsigned long end)
 {
 	unsigned long next;
@@ -825,7 +825,7 @@ static void remove_pmd_table(pmd_t *pmd_start, unsigned long addr,
 	}
 }
 
-static void remove_pud_table(pud_t *pud_start, unsigned long addr,
+static void __meminit remove_pud_table(pud_t *pud_start, unsigned long addr,
 			     unsigned long end)
 {
 	unsigned long next;
diff --git a/arch/powerpc/sysdev/xive/spapr.c b/arch/powerpc/sysdev/xive/spapr.c
index f0551a2be9df..1e3674d7ea7b 100644
--- a/arch/powerpc/sysdev/xive/spapr.c
+++ b/arch/powerpc/sysdev/xive/spapr.c
@@ -768,7 +768,7 @@ static const u8 *get_vec5_feature(unsigned int index)
 	return vec5 + index;
 }
 
-static bool xive_spapr_disabled(void)
+static bool __init xive_spapr_disabled(void)
 {
 	const u8 *vec5_xive;
 
-- 
2.26.2

Re: [PATCH] powerpc: fix function annotations to avoid section mismatch warnings with gcc-10

[Segher Boessenkool]

On Wed, Jul 29, 2020 at 03:37:41PM +0200, Vladis Dronov wrote:
> Certain warnings are emitted for powerpc code when building with a gcc-10
> toolset:
> 
>     WARNING: modpost: vmlinux.o(.text.unlikely+0x377c): Section mismatch in
>     reference from the function remove_pmd_table() to the function
>     .meminit.text:split_kernel_mapping()
>     The function remove_pmd_table() references
>     the function __meminit split_kernel_mapping().
>     This is often because remove_pmd_table lacks a __meminit
>     annotation or the annotation of split_kernel_mapping is wrong.
> 
> Add the appropriate __init and __meminit annotations to make modpost not
> complain. In all the cases there are just a single callsite from another
> __init or __meminit function:
> 
> __meminit remove_pagetable() -> remove_pud_table() -> remove_pmd_table()
> __init prom_init() -> setup_secure_guest()
> __init xive_spapr_init() -> xive_spapr_disabled()

So what changed?  These functions were inlined with older compilers, but
not anymore?


Segher

Re: [PATCH] powerpc: fix function annotations to avoid section mismatch warnings with gcc-10

[Vladis Dronov]

Hello,

----- Original Message -----
> From: "Segher Boessenkool" <segher@kernel.crashing.org>
> To: "Vladis Dronov" <vdronov@redhat.com>
> Cc: linuxppc-dev@lists.ozlabs.org, "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>, linux-kernel@vger.kernel.org,
> "Paul Mackerras" <paulus@samba.org>
> Sent: Wednesday, July 29, 2020 4:49:49 PM
> Subject: Re: [PATCH] powerpc: fix function annotations to avoid section mismatch warnings with gcc-10
> 
> On Wed, Jul 29, 2020 at 03:37:41PM +0200, Vladis Dronov wrote:
> > Certain warnings are emitted for powerpc code when building with a gcc-10
> > toolset:
> > 
> >     WARNING: modpost: vmlinux.o(.text.unlikely+0x377c): Section mismatch in
> >     reference from the function remove_pmd_table() to the function
> >     .meminit.text:split_kernel_mapping()
> >     The function remove_pmd_table() references
> >     the function __meminit split_kernel_mapping().
> >     This is often because remove_pmd_table lacks a __meminit
> >     annotation or the annotation of split_kernel_mapping is wrong.
> > 
> > Add the appropriate __init and __meminit annotations to make modpost not
> > complain. In all the cases there are just a single callsite from another
> > __init or __meminit function:
> > 
> > __meminit remove_pagetable() -> remove_pud_table() -> remove_pmd_table()
> > __init prom_init() -> setup_secure_guest()
> > __init xive_spapr_init() -> xive_spapr_disabled()
> 
> So what changed?  These functions were inlined with older compilers, but
> not anymore?

Yes, exactly. Gcc-10 does not inline them anymore. If this is because of my
build system, this can happen to others also.

The same thing was fixed by Linus in e99332e7b4cd ("gcc-10: mark more functions
__init to avoid section mismatch warnings").

> 
> Segher

Best regards,
Vladis Dronov | Red Hat, Inc. | The Core Kernel | Senior Software Engineer

Re: [PATCH] powerpc: fix function annotations to avoid section mismatch warnings with gcc-10

[Segher Boessenkool]

On Wed, Jul 29, 2020 at 03:44:56PM -0400, Vladis Dronov wrote:
> > > Certain warnings are emitted for powerpc code when building with a gcc-10
> > > toolset:
> > > 
> > >     WARNING: modpost: vmlinux.o(.text.unlikely+0x377c): Section mismatch in
> > >     reference from the function remove_pmd_table() to the function
> > >     .meminit.text:split_kernel_mapping()
> > >     The function remove_pmd_table() references
> > >     the function __meminit split_kernel_mapping().
> > >     This is often because remove_pmd_table lacks a __meminit
> > >     annotation or the annotation of split_kernel_mapping is wrong.
> > > 
> > > Add the appropriate __init and __meminit annotations to make modpost not
> > > complain. In all the cases there are just a single callsite from another
> > > __init or __meminit function:
> > > 
> > > __meminit remove_pagetable() -> remove_pud_table() -> remove_pmd_table()
> > > __init prom_init() -> setup_secure_guest()
> > > __init xive_spapr_init() -> xive_spapr_disabled()
> > 
> > So what changed?  These functions were inlined with older compilers, but
> > not anymore?
> 
> Yes, exactly. Gcc-10 does not inline them anymore. If this is because of my
> build system, this can happen to others also.
> 
> The same thing was fixed by Linus in e99332e7b4cd ("gcc-10: mark more functions
> __init to avoid section mismatch warnings").

It sounds like this is part of "-finline-functions was retuned" on
<https://gcc.gnu.org/gcc-10/changes.html>?  So everyone should see it
(no matter what config or build system), and it is a good thing too :-)

Thanks for the confirmation,


Segher

Re: [PATCH] powerpc: fix function annotations to avoid section mismatch warnings with gcc-10

[Michael Ellerman]

Segher Boessenkool <segher@kernel.crashing.org> writes:
> On Wed, Jul 29, 2020 at 03:44:56PM -0400, Vladis Dronov wrote:
>> > > Certain warnings are emitted for powerpc code when building with a gcc-10
>> > > toolset:
>> > > 
>> > >     WARNING: modpost: vmlinux.o(.text.unlikely+0x377c): Section mismatch in
>> > >     reference from the function remove_pmd_table() to the function
>> > >     .meminit.text:split_kernel_mapping()
>> > >     The function remove_pmd_table() references
>> > >     the function __meminit split_kernel_mapping().
>> > >     This is often because remove_pmd_table lacks a __meminit
>> > >     annotation or the annotation of split_kernel_mapping is wrong.
>> > > 
>> > > Add the appropriate __init and __meminit annotations to make modpost not
>> > > complain. In all the cases there are just a single callsite from another
>> > > __init or __meminit function:
>> > > 
>> > > __meminit remove_pagetable() -> remove_pud_table() -> remove_pmd_table()
>> > > __init prom_init() -> setup_secure_guest()
>> > > __init xive_spapr_init() -> xive_spapr_disabled()
>> > 
>> > So what changed?  These functions were inlined with older compilers, but
>> > not anymore?
>> 
>> Yes, exactly. Gcc-10 does not inline them anymore. If this is because of my
>> build system, this can happen to others also.
>> 
>> The same thing was fixed by Linus in e99332e7b4cd ("gcc-10: mark more functions
>> __init to avoid section mismatch warnings").
>
> It sounds like this is part of "-finline-functions was retuned" on
> <https://gcc.gnu.org/gcc-10/changes.html>?  So everyone should see it
> (no matter what config or build system), and it is a good thing too :-)

I haven't seen it in my GCC 10 builds, so there must be some other
subtlety. Probably it depends on details of the .config.

cheers

Re: [PATCH] powerpc: fix function annotations to avoid section mismatch warnings with gcc-10

[Vladis Dronov]

Hello, Michael,

----- Original Message -----
> From: "Michael Ellerman" <mpe@ellerman.id.au>
> Subject: Re: [PATCH] powerpc: fix function annotations to avoid section mismatch warnings with gcc-10
> 
...
> >> > So what changed?  These functions were inlined with older compilers, but
> >> > not anymore?
> >> 
> >> Yes, exactly. Gcc-10 does not inline them anymore. If this is because of
> >> my
> >> build system, this can happen to others also.
> >> 
> >> The same thing was fixed by Linus in e99332e7b4cd ("gcc-10: mark more
> >> functions
> >> __init to avoid section mismatch warnings").
> >
> > It sounds like this is part of "-finline-functions was retuned" on
> > <https://gcc.gnu.org/gcc-10/changes.html>?  So everyone should see it
> > (no matter what config or build system), and it is a good thing too :-)
> 
> I haven't seen it in my GCC 10 builds, so there must be some other
> subtlety. Probably it depends on details of the .config.
> 

I've just had this building the latest upstream for the ppc64le with a derivative
of the RHEL-8 config. This can probably be a compiler/linker setting, like -O2
versus -O3.

> cheers

Best regards,
Vladis Dronov | Red Hat, Inc. | The Core Kernel | Senior Software Engineer

Re: [PATCH] powerpc: fix function annotations to avoid section mismatch warnings with gcc-10

[Michael Ellerman]

On Wed, 29 Jul 2020 15:37:41 +0200, Vladis Dronov wrote:
> Certain warnings are emitted for powerpc code when building with a gcc-10
> toolset:
> 
>     WARNING: modpost: vmlinux.o(.text.unlikely+0x377c): Section mismatch in
>     reference from the function remove_pmd_table() to the function
>     .meminit.text:split_kernel_mapping()
>     The function remove_pmd_table() references
>     the function __meminit split_kernel_mapping().
>     This is often because remove_pmd_table lacks a __meminit
>     annotation or the annotation of split_kernel_mapping is wrong.
> 
> [...]

Applied to powerpc/next.

[1/1] powerpc: fix function annotations to avoid section mismatch warnings with gcc-10
      https://git.kernel.org/powerpc/c/aff779515a070df7e23da9e86f1096f7d10d647e

cheers