[PATCH v3 0/4] arm64: put objects into proper sections

[PATCH v3 0/4] arm64: put objects into proper sections

[Jisheng Zhang]

This series tries to put some objects into proper sections.

patch1 puts alloc_vectors_page() into .init section. This is a clean up
patch.
patch2 constify vm_special_mapping used for aarch32 vectors page.
patch3 fix the incorrect placement of __initdata and __read_mostly
patch4 apply __ro_after_init to some objects

Previously I only want to mark vdso_pages, vdso_spec, vectors_page and
cpu_ops as __read_mostly for performance reason. Then inspired by
Kees's patch[1], I think __ro_after_init is better.

[1] http://www.spinics.net/lists/arm-kernel/msg523188.html

Changes since v2:
  - include <linux/cache.h> for __ro_after_init, thank Mark's suggestions
  - make vdso_spec[0].pages and vdso_spec[1].pages assignment style
    consistent, thank Mark for pointing it out.

Changes since v1:
  - use __ro_after_init instead of __read_mostly
  - find more objects to be suitable for __ro_after_init
  - add one more patch to fix the incorrect placement of __initdata and
    __read_mostly


Jisheng Zhang (4):
  arm64: vdso: add __init section marker to alloc_vectors_page
  arm64: vdso: constify vm_special_mapping used for aarch32 vectors page
  arm64: kaslr: Fix incorrect placement of __initdata and __read_mostly
  arm64: apply __ro_after_init to some objects

 arch/arm64/kernel/cpu_ops.c |  2 +-
 arch/arm64/kernel/kaslr.c   |  4 ++--
 arch/arm64/kernel/vdso.c    | 32 ++++++++++++++++----------------
 arch/arm64/mm/dma-mapping.c |  2 +-
 arch/arm64/mm/init.c        |  4 ++--
 arch/arm64/mm/mmu.c         |  2 +-
 6 files changed, 23 insertions(+), 23 deletions(-)

-- 
2.8.1

[PATCH v3 1/4] arm64: vdso: add __init section marker to alloc_vectors_page

[Jisheng Zhang]

It is not needed after booting, this patch moves the alloc_vectors_page
function to the __init section.

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
---
 arch/arm64/kernel/vdso.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 076312b..e320e8f 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -55,7 +55,7 @@ struct vdso_data *vdso_data = &vdso_data_store.data;
  */
 static struct page *vectors_page[1];
 
-static int alloc_vectors_page(void)
+static int __init alloc_vectors_page(void)
 {
 	extern char __kuser_helper_start[], __kuser_helper_end[];
 	extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[];
-- 
2.8.1

[PATCH v3 2/4] arm64: vdso: constify vm_special_mapping used for aarch32 vectors page

[Jisheng Zhang]

The vm_special_mapping spec which is used for aarch32 vectors page is
never modified, so mark it as const.

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
---
 arch/arm64/kernel/vdso.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index e320e8f..10ad8ab 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -88,7 +88,7 @@ int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
 {
 	struct mm_struct *mm = current->mm;
 	unsigned long addr = AARCH32_VECTORS_BASE;
-	static struct vm_special_mapping spec = {
+	static const struct vm_special_mapping spec = {
 		.name	= "[vectors]",
 		.pages	= vectors_page,
 
-- 
2.8.1

[PATCH v3 3/4] arm64: kaslr: Fix incorrect placement of __initdata and __read_mostly

[Jisheng Zhang]

__initdata and __read_mostly should be placed after the variable name
for the variable to be placed in the intended section.

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
---
 arch/arm64/kernel/kaslr.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
index b054691..8ebabc4 100644
--- a/arch/arm64/kernel/kaslr.c
+++ b/arch/arm64/kernel/kaslr.c
@@ -20,8 +20,8 @@
 #include <asm/pgtable.h>
 #include <asm/sections.h>
 
-u64 __read_mostly module_alloc_base;
-u16 __initdata memstart_offset_seed;
+u64 module_alloc_base __read_mostly;
+u16 memstart_offset_seed __initdata;
 
 static __init u64 get_kaslr_seed(void *fdt)
 {
-- 
2.8.1

Re: [PATCH v3 3/4] arm64: kaslr: Fix incorrect placement of __initdata and __read_mostly

[Ard Biesheuvel]

Hi Jisheng,

On 12 August 2016 at 10:01, Jisheng Zhang <jszhang@marvell.com> wrote:
> __initdata and __read_mostly should be placed after the variable name
> for the variable to be placed in the intended section.
>

Why?

> Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
> ---
>  arch/arm64/kernel/kaslr.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
> index b054691..8ebabc4 100644
> --- a/arch/arm64/kernel/kaslr.c
> +++ b/arch/arm64/kernel/kaslr.c
> @@ -20,8 +20,8 @@
>  #include <asm/pgtable.h>
>  #include <asm/sections.h>
>
> -u64 __read_mostly module_alloc_base;
> -u16 __initdata memstart_offset_seed;
> +u64 module_alloc_base __read_mostly;
> +u16 memstart_offset_seed __initdata;
>
>  static __init u64 get_kaslr_seed(void *fdt)
>  {
> --
> 2.8.1
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH v3 3/4] arm64: kaslr: Fix incorrect placement of __initdata and __read_mostly

[Jisheng Zhang]

Hi Ard,

On Fri, 12 Aug 2016 14:02:40 +0200 Ard Biesheuvel wrote:

> Hi Jisheng,
> 
> On 12 August 2016 at 10:01, Jisheng Zhang <jszhang@marvell.com> wrote:
> > __initdata and __read_mostly should be placed after the variable name
> > for the variable to be placed in the intended section.
> >  
> 
> Why?

include/linux/init.h says something as:

 * For initialized data:
 * You should insert __initdata or __initconst between the variable name
 * and equal sign followed by value, e.g.:
 *
 * static int init_variable __initdata = 0;
 * static const char linux_logo[] __initconst = { 0x32, 0x36, ... };

and examples in gcc manual also put __attribute__ (...) after variable name.

https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#Common-Variable-Attributes

Then I grep the source, found most lines (especially arch/arm64/*) put the
__initdata and __read_mostly after the variable name.

However, I built the code with three different gcc, the result looks identical
no matter where these markers put. So the commit msg looks wrong, what about
changes it as

"put __initdata and __read_mostly after the variable name
to keep the style consistent"?

Thanks,
Jisheng

> 
> > Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
> > ---
> >  arch/arm64/kernel/kaslr.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
> > index b054691..8ebabc4 100644
> > --- a/arch/arm64/kernel/kaslr.c
> > +++ b/arch/arm64/kernel/kaslr.c
> > @@ -20,8 +20,8 @@
> >  #include <asm/pgtable.h>
> >  #include <asm/sections.h>
> >
> > -u64 __read_mostly module_alloc_base;
> > -u16 __initdata memstart_offset_seed;
> > +u64 module_alloc_base __read_mostly;
> > +u16 memstart_offset_seed __initdata;
> >
> >  static __init u64 get_kaslr_seed(void *fdt)
> >  {
> > --
> > 2.8.1
> >
> >
> > _______________________________________________
> > linux-arm-kernel mailing list
> > linux-arm-kernel@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel  

Re: [PATCH v3 3/4] arm64: kaslr: Fix incorrect placement of __initdata and __read_mostly

[Jisheng Zhang]

Hi Ard,

On Mon, 15 Aug 2016 12:52:14 +0800 Jisheng Zhang wrote:

> Hi Ard,
> 
> On Fri, 12 Aug 2016 14:02:40 +0200 Ard Biesheuvel wrote:
> 
> > Hi Jisheng,
> > 
> > On 12 August 2016 at 10:01, Jisheng Zhang <jszhang@marvell.com> wrote:  
> > > __initdata and __read_mostly should be placed after the variable name
> > > for the variable to be placed in the intended section.
> > >    
> > 
> > Why?  
> 
> include/linux/init.h says something as:
> 
>  * For initialized data:
>  * You should insert __initdata or __initconst between the variable name
>  * and equal sign followed by value, e.g.:
>  *
>  * static int init_variable __initdata = 0;
>  * static const char linux_logo[] __initconst = { 0x32, 0x36, ... };
> 
> and examples in gcc manual also put __attribute__ (...) after variable name.
> 
> https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#Common-Variable-Attributes
> 
> Then I grep the source, found most lines (especially arch/arm64/*) put the
> __initdata and __read_mostly after the variable name.
> 
> However, I built the code with three different gcc, the result looks identical
> no matter where these markers put. So the commit msg looks wrong, what about
> changes it as
> 
> "put __initdata and __read_mostly after the variable name
> to keep the style consistent"?

After some consideration, I want to drop this patch in newer version since
it's not a bug, just "style"

Thanks for your reviewing,
Jisheng

Re: [PATCH v3 3/4] arm64: kaslr: Fix incorrect placement of __initdata and __read_mostly

[Ard Biesheuvel]

On 15 August 2016 at 07:57, Jisheng Zhang <jszhang@marvell.com> wrote:
> Hi Ard,
>
> On Mon, 15 Aug 2016 12:52:14 +0800 Jisheng Zhang wrote:
>
>> Hi Ard,
>>
>> On Fri, 12 Aug 2016 14:02:40 +0200 Ard Biesheuvel wrote:
>>
>> > Hi Jisheng,
>> >
>> > On 12 August 2016 at 10:01, Jisheng Zhang <jszhang@marvell.com> wrote:
>> > > __initdata and __read_mostly should be placed after the variable name
>> > > for the variable to be placed in the intended section.
>> > >
>> >
>> > Why?
>>
>> include/linux/init.h says something as:
>>
>>  * For initialized data:
>>  * You should insert __initdata or __initconst between the variable name
>>  * and equal sign followed by value, e.g.:
>>  *
>>  * static int init_variable __initdata = 0;
>>  * static const char linux_logo[] __initconst = { 0x32, 0x36, ... };
>>
>> and examples in gcc manual also put __attribute__ (...) after variable name.
>>
>> https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#Common-Variable-Attributes
>>
>> Then I grep the source, found most lines (especially arch/arm64/*) put the
>> __initdata and __read_mostly after the variable name.
>>
>> However, I built the code with three different gcc, the result looks identical
>> no matter where these markers put. So the commit msg looks wrong, what about
>> changes it as
>>
>> "put __initdata and __read_mostly after the variable name
>> to keep the style consistent"?
>
> After some consideration, I want to drop this patch in newer version since
> it's not a bug, just "style"
>

OK, thanks for clearing that up. I don't object to the patch, but I
wanted to get confirmation that the current code is also correct.

Thanks,
Ard.

[PATCH v3 4/4] arm64: apply __ro_after_init to some objects

[Jisheng Zhang]

These objects are set during initialization, thereafter are read only.

Previously I only want to mark vdso_pages, vdso_spec, vectors_page and
cpu_ops as __read_mostly from performance point of view. Then inspired
by Kees's patch[1] to apply more __ro_after_init for arm, I think it's
better to mark them as __ro_after_init. What's more, I find some more
objects are also read only after init. So apply __ro_after_init to all
of them.

This patch also removes global vdso_pagelist and tries to clean up
vdso_spec[] assignment code.

[1] http://www.spinics.net/lists/arm-kernel/msg523188.html

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
---
 arch/arm64/kernel/cpu_ops.c |  2 +-
 arch/arm64/kernel/kaslr.c   |  2 +-
 arch/arm64/kernel/vdso.c    | 28 ++++++++++++++--------------
 arch/arm64/mm/dma-mapping.c |  2 +-
 arch/arm64/mm/init.c        |  4 ++--
 arch/arm64/mm/mmu.c         |  2 +-
 6 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/arch/arm64/kernel/cpu_ops.c b/arch/arm64/kernel/cpu_ops.c
index c7cfb8f..6d32d1a 100644
--- a/arch/arm64/kernel/cpu_ops.c
+++ b/arch/arm64/kernel/cpu_ops.c
@@ -28,7 +28,7 @@ extern const struct cpu_operations smp_spin_table_ops;
 extern const struct cpu_operations acpi_parking_protocol_ops;
 extern const struct cpu_operations cpu_psci_ops;
 
-const struct cpu_operations *cpu_ops[NR_CPUS];
+const struct cpu_operations *cpu_ops[NR_CPUS] __ro_after_init;
 
 static const struct cpu_operations *dt_supported_cpu_ops[] __initconst = {
 	&smp_spin_table_ops,
diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
index 8ebabc4..93c47e1 100644
--- a/arch/arm64/kernel/kaslr.c
+++ b/arch/arm64/kernel/kaslr.c
@@ -20,7 +20,7 @@
 #include <asm/pgtable.h>
 #include <asm/sections.h>
 
-u64 module_alloc_base __read_mostly;
+u64 module_alloc_base __ro_after_init;
 u16 memstart_offset_seed __initdata;
 
 static __init u64 get_kaslr_seed(void *fdt)
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 10ad8ab..c1ff7c2 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -19,6 +19,7 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/cache.h>
 #include <linux/clocksource.h>
 #include <linux/elf.h>
 #include <linux/err.h>
@@ -37,8 +38,7 @@
 #include <asm/vdso_datapage.h>
 
 extern char vdso_start, vdso_end;
-static unsigned long vdso_pages;
-static struct page **vdso_pagelist;
+static unsigned long vdso_pages __ro_after_init;
 
 /*
  * The vDSO data page.
@@ -53,7 +53,7 @@ struct vdso_data *vdso_data = &vdso_data_store.data;
 /*
  * Create and map the vectors page for AArch32 tasks.
  */
-static struct page *vectors_page[1];
+static struct page *vectors_page[1] __ro_after_init;
 
 static int __init alloc_vectors_page(void)
 {
@@ -110,11 +110,19 @@ int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
 }
 #endif /* CONFIG_COMPAT */
 
-static struct vm_special_mapping vdso_spec[2];
+static struct vm_special_mapping vdso_spec[2] __ro_after_init = {
+	{
+		.name	= "[vvar]",
+	},
+	{
+		.name	= "[vdso]",
+	},
+};
 
 static int __init vdso_init(void)
 {
 	int i;
+	struct page **vdso_pagelist;
 
 	if (memcmp(&vdso_start, "\177ELF", 4)) {
 		pr_err("vDSO is not a valid ELF object!\n");
@@ -138,16 +146,8 @@ static int __init vdso_init(void)
 	for (i = 0; i < vdso_pages; i++)
 		vdso_pagelist[i + 1] = pfn_to_page(PHYS_PFN(__pa(&vdso_start)) + i);
 
-	/* Populate the special mapping structures */
-	vdso_spec[0] = (struct vm_special_mapping) {
-		.name	= "[vvar]",
-		.pages	= vdso_pagelist,
-	};
-
-	vdso_spec[1] = (struct vm_special_mapping) {
-		.name	= "[vdso]",
-		.pages	= &vdso_pagelist[1],
-	};
+	vdso_spec[0].pages = &vdso_pagelist[0];
+	vdso_spec[1].pages = &vdso_pagelist[1];
 
 	return 0;
 }
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index c4284c4..59d44e7 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -30,7 +30,7 @@
 
 #include <asm/cacheflush.h>
 
-static int swiotlb __read_mostly;
+static int swiotlb __ro_after_init;
 
 static pgprot_t __get_dma_pgprot(unsigned long attrs, pgprot_t prot,
 				 bool coherent)
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index bbb7ee7..e8b81ea 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -55,8 +55,8 @@
  * executes, which assigns it its actual value. So use a default value
  * that cannot be mistaken for a real physical address.
  */
-s64 memstart_addr __read_mostly = -1;
-phys_addr_t arm64_dma_phys_limit __read_mostly;
+s64 memstart_addr __ro_after_init = -1;
+phys_addr_t arm64_dma_phys_limit __ro_after_init;
 
 #ifdef CONFIG_BLK_DEV_INITRD
 static int __init early_initrd(char *p)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 4989948..6029bed 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -46,7 +46,7 @@
 
 u64 idmap_t0sz = TCR_T0SZ(VA_BITS);
 
-u64 kimage_voffset __read_mostly;
+u64 kimage_voffset __ro_after_init;
 EXPORT_SYMBOL(kimage_voffset);
 
 /*
-- 
2.8.1

Re: [PATCH v3 4/4] arm64: apply __ro_after_init to some objects

[Mark Rutland]

Hi,

There are still a few missing includes as of this patch, and I have a
small nit about one file as commented below.

Please fix up the includes.

On Fri, Aug 12, 2016 at 04:01:11PM +0800, Jisheng Zhang wrote:
> diff --git a/arch/arm64/kernel/cpu_ops.c b/arch/arm64/kernel/cpu_ops.c
> index c7cfb8f..6d32d1a 100644
> --- a/arch/arm64/kernel/cpu_ops.c
> +++ b/arch/arm64/kernel/cpu_ops.c
> @@ -28,7 +28,7 @@ extern const struct cpu_operations smp_spin_table_ops;
>  extern const struct cpu_operations acpi_parking_protocol_ops;
>  extern const struct cpu_operations cpu_psci_ops;
>  
> -const struct cpu_operations *cpu_ops[NR_CPUS];
> +const struct cpu_operations *cpu_ops[NR_CPUS] __ro_after_init;

This file is missing a <linux/cache.h> include for __ro_after_init.

>  static const struct cpu_operations *dt_supported_cpu_ops[] __initconst = {
>  	&smp_spin_table_ops,
> diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
> index 8ebabc4..93c47e1 100644
> --- a/arch/arm64/kernel/kaslr.c
> +++ b/arch/arm64/kernel/kaslr.c
> @@ -20,7 +20,7 @@
>  #include <asm/pgtable.h>
>  #include <asm/sections.h>
>  
> -u64 module_alloc_base __read_mostly;
> +u64 module_alloc_base __ro_after_init;

Likewise.

>  u16 memstart_offset_seed __initdata;
>  
>  static __init u64 get_kaslr_seed(void *fdt)
> diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
> index 10ad8ab..c1ff7c2 100644
> --- a/arch/arm64/kernel/vdso.c
> +++ b/arch/arm64/kernel/vdso.c
> @@ -19,6 +19,7 @@
>   */
>  
>  #include <linux/kernel.h>
> +#include <linux/cache.h>
>  #include <linux/clocksource.h>
>  #include <linux/elf.h>
>  #include <linux/err.h>

Nit: Could you please sort this list? Everything but <linux/kernel.h> is
already in order.

> diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
> index c4284c4..59d44e7 100644
> --- a/arch/arm64/mm/dma-mapping.c
> +++ b/arch/arm64/mm/dma-mapping.c
> @@ -30,7 +30,7 @@
>  
>  #include <asm/cacheflush.h>
>  
> -static int swiotlb __read_mostly;
> +static int swiotlb __ro_after_init;

This file is missing a <linux/cache.h> include for __ro_after_init.

>  
>  static pgprot_t __get_dma_pgprot(unsigned long attrs, pgprot_t prot,
>  				 bool coherent)
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index bbb7ee7..e8b81ea 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -55,8 +55,8 @@
>   * executes, which assigns it its actual value. So use a default value
>   * that cannot be mistaken for a real physical address.
>   */
> -s64 memstart_addr __read_mostly = -1;
> -phys_addr_t arm64_dma_phys_limit __read_mostly;
> +s64 memstart_addr __ro_after_init = -1;
> +phys_addr_t arm64_dma_phys_limit __ro_after_init;

Likewise.

>  #ifdef CONFIG_BLK_DEV_INITRD
>  static int __init early_initrd(char *p)
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 4989948..6029bed 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -46,7 +46,7 @@
>  
>  u64 idmap_t0sz = TCR_T0SZ(VA_BITS);
>  
> -u64 kimage_voffset __read_mostly;
> +u64 kimage_voffset __ro_after_init;

Likewise.

Thanks,
Mark.

Re: [PATCH v3 4/4] arm64: apply __ro_after_init to some objects

[Jisheng Zhang]

Hi Mark,

On Fri, 12 Aug 2016 13:43:45 +0100 Mark Rutland wrote:

> Hi,
> 
> There are still a few missing includes as of this patch, and I have a
> small nit about one file as commented below.
> 
> Please fix up the includes.
> 
> On Fri, Aug 12, 2016 at 04:01:11PM +0800, Jisheng Zhang wrote:
> > diff --git a/arch/arm64/kernel/cpu_ops.c b/arch/arm64/kernel/cpu_ops.c
> > index c7cfb8f..6d32d1a 100644
> > --- a/arch/arm64/kernel/cpu_ops.c
> > +++ b/arch/arm64/kernel/cpu_ops.c
> > @@ -28,7 +28,7 @@ extern const struct cpu_operations smp_spin_table_ops;
> >  extern const struct cpu_operations acpi_parking_protocol_ops;
> >  extern const struct cpu_operations cpu_psci_ops;
> >  
> > -const struct cpu_operations *cpu_ops[NR_CPUS];
> > +const struct cpu_operations *cpu_ops[NR_CPUS] __ro_after_init;  
> 
> This file is missing a <linux/cache.h> include for __ro_after_init.
> 
> >  static const struct cpu_operations *dt_supported_cpu_ops[] __initconst = {
> >  	&smp_spin_table_ops,
> > diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
> > index 8ebabc4..93c47e1 100644
> > --- a/arch/arm64/kernel/kaslr.c
> > +++ b/arch/arm64/kernel/kaslr.c
> > @@ -20,7 +20,7 @@
> >  #include <asm/pgtable.h>
> >  #include <asm/sections.h>
> >  
> > -u64 module_alloc_base __read_mostly;
> > +u64 module_alloc_base __ro_after_init;  
> 
> Likewise.
> 
> >  u16 memstart_offset_seed __initdata;
> >  
> >  static __init u64 get_kaslr_seed(void *fdt)
> > diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
> > index 10ad8ab..c1ff7c2 100644
> > --- a/arch/arm64/kernel/vdso.c
> > +++ b/arch/arm64/kernel/vdso.c
> > @@ -19,6 +19,7 @@
> >   */
> >  
> >  #include <linux/kernel.h>
> > +#include <linux/cache.h>
> >  #include <linux/clocksource.h>
> >  #include <linux/elf.h>
> >  #include <linux/err.h>  
> 
> Nit: Could you please sort this list? Everything but <linux/kernel.h> is
> already in order.
> 
> > diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
> > index c4284c4..59d44e7 100644
> > --- a/arch/arm64/mm/dma-mapping.c
> > +++ b/arch/arm64/mm/dma-mapping.c
> > @@ -30,7 +30,7 @@
> >  
> >  #include <asm/cacheflush.h>
> >  
> > -static int swiotlb __read_mostly;
> > +static int swiotlb __ro_after_init;  
> 
> This file is missing a <linux/cache.h> include for __ro_after_init.
> 
> >  
> >  static pgprot_t __get_dma_pgprot(unsigned long attrs, pgprot_t prot,
> >  				 bool coherent)
> > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> > index bbb7ee7..e8b81ea 100644
> > --- a/arch/arm64/mm/init.c
> > +++ b/arch/arm64/mm/init.c
> > @@ -55,8 +55,8 @@
> >   * executes, which assigns it its actual value. So use a default value
> >   * that cannot be mistaken for a real physical address.
> >   */
> > -s64 memstart_addr __read_mostly = -1;
> > -phys_addr_t arm64_dma_phys_limit __read_mostly;
> > +s64 memstart_addr __ro_after_init = -1;
> > +phys_addr_t arm64_dma_phys_limit __ro_after_init;  
> 
> Likewise.
> 
> >  #ifdef CONFIG_BLK_DEV_INITRD
> >  static int __init early_initrd(char *p)
> > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> > index 4989948..6029bed 100644
> > --- a/arch/arm64/mm/mmu.c
> > +++ b/arch/arm64/mm/mmu.c
> > @@ -46,7 +46,7 @@
> >  
> >  u64 idmap_t0sz = TCR_T0SZ(VA_BITS);
> >  
> > -u64 kimage_voffset __read_mostly;
> > +u64 kimage_voffset __ro_after_init;  
> 
> Likewise.
> 

Thanks a lot, all comments are addressed in v4.

the headers in vdso.c is sorted now. However, the headers in mmu.c,
dma-mapping.c, init.c aren't, for I dunno whether it's acceptable
to do so. Or we could add one separate patch to make them sorted before
applying __ro_after_init

Thanks,
Jisheng

Re: [PATCH v3 4/4] arm64: apply __ro_after_init to some objects

[Mark Rutland]

Hi,

On Mon, Aug 15, 2016 at 02:53:03PM +0800, Jisheng Zhang wrote:
> On Fri, 12 Aug 2016 13:43:45 +0100 Mark Rutland wrote:
> > On Fri, Aug 12, 2016 at 04:01:11PM +0800, Jisheng Zhang wrote:
> > > diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
> > > index 10ad8ab..c1ff7c2 100644
> > > --- a/arch/arm64/kernel/vdso.c
> > > +++ b/arch/arm64/kernel/vdso.c
> > > @@ -19,6 +19,7 @@
> > >   */
> > >  
> > >  #include <linux/kernel.h>
> > > +#include <linux/cache.h>
> > >  #include <linux/clocksource.h>
> > >  #include <linux/elf.h>
> > >  #include <linux/err.h>  
> > 
> > Nit: Could you please sort this list? Everything but <linux/kernel.h> is
> > already in order.

[...]

> Thanks a lot, all comments are addressed in v4.
> 
> the headers in vdso.c is sorted now. However, the headers in mmu.c,
> dma-mapping.c, init.c aren't, for I dunno whether it's acceptable
> to do so. Or we could add one separate patch to make them sorted before
> applying __ro_after_init

Ah. Given that's a little messy, it's probably not worthwhile sorting them.
Further, feel free to not bother sorting the vdso.c includes.

Thanks,
Mark.