| Message ID | 1470922609-754-5-git-send-email-jszhang@marvell.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi, On Thu, Aug 11, 2016 at 09:36:49PM +0800, Jisheng Zhang wrote: > 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 | 27 +++++++++++++-------------- > arch/arm64/mm/dma-mapping.c | 2 +- > arch/arm64/mm/init.c | 4 ++-- > arch/arm64/mm/mmu.c | 2 +- > 6 files changed, 19 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; It looks like we need to include <linux/cache.h> for __ro_after_init. While we seem to get that via some transitive include, that's not guaranteed to remain the case, and it's not something we should rely upon. Please explicitly include <linux/cache.h> when __ro_after_init is added. > - /* 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; > + vdso_spec[1].pages = &vdso_pagelist[1]; While the original code was also this way, could we please make these a little more consistent? e.g. vdso_spec[0].pages = &vdso_pagelist[0]; vdso_spec[1].pages = &vdso_pagelist[1]; That way it raises few false alarms for anyone looking at the code. Otherwise, this patch looks largely fine. Thanks, Mark.
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..0af41de 100644 --- a/arch/arm64/kernel/vdso.c +++ b/arch/arm64/kernel/vdso.c @@ -37,8 +37,7 @@ #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 +52,7 @@ 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 +109,19 @@ 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 +145,8 @@ 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; + 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); /*
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 | 27 +++++++++++++-------------- arch/arm64/mm/dma-mapping.c | 2 +- arch/arm64/mm/init.c | 4 ++-- arch/arm64/mm/mmu.c | 2 +- 6 files changed, 19 insertions(+), 20 deletions(-)