From e6eb5fe9123f05dcbf339ae5c0b6d32fcc0685d5 Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Tue, 7 May 2019 20:19:05 +0200 Subject: parisc: Drop LDCW barrier in CAS code when running UP When running an SMP kernel on a single-CPU machine, we can speed up the CAS code by replacing the LDCW sync barrier with NOP. Signed-off-by: Helge Deller --- arch/parisc/kernel/syscall.S | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'arch') diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S index e54d5e4d3489..97ac707c6bff 100644 --- a/arch/parisc/kernel/syscall.S +++ b/arch/parisc/kernel/syscall.S @@ -641,7 +641,8 @@ cas_action: 2: stw %r24, 0(%r26) /* Free lock */ #ifdef CONFIG_SMP - LDCW 0(%sr2,%r20), %r1 /* Barrier */ +98: LDCW 0(%sr2,%r20), %r1 /* Barrier */ +99: ALTERNATIVE(98b, 99b, ALT_COND_NO_SMP, INSN_NOP) #endif stw %r20, 0(%sr2,%r20) #if ENABLE_LWS_DEBUG @@ -658,7 +659,8 @@ cas_action: /* Error occurred on load or store */ /* Free lock */ #ifdef CONFIG_SMP - LDCW 0(%sr2,%r20), %r1 /* Barrier */ +98: LDCW 0(%sr2,%r20), %r1 /* Barrier */ +99: ALTERNATIVE(98b, 99b, ALT_COND_NO_SMP, INSN_NOP) #endif stw %r20, 0(%sr2,%r20) #if ENABLE_LWS_DEBUG @@ -862,7 +864,8 @@ cas2_action: cas2_end: /* Free lock */ #ifdef CONFIG_SMP - LDCW 0(%sr2,%r20), %r1 /* Barrier */ +98: LDCW 0(%sr2,%r20), %r1 /* Barrier */ +99: ALTERNATIVE(98b, 99b, ALT_COND_NO_SMP, INSN_NOP) #endif stw %r20, 0(%sr2,%r20) /* Enable interrupts */ @@ -875,7 +878,8 @@ cas2_end: /* Error occurred on load or store */ /* Free lock */ #ifdef CONFIG_SMP - LDCW 0(%sr2,%r20), %r1 /* Barrier */ +98: LDCW 0(%sr2,%r20), %r1 /* Barrier */ +99: ALTERNATIVE(98b, 99b, ALT_COND_NO_SMP, INSN_NOP) #endif stw %r20, 0(%sr2,%r20) ssm PSW_SM_I, %r0 -- cgit v1.2.3 From 8d0e051cc75e2b1a7e2fd51fc56af332c9619618 Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Fri, 10 May 2019 17:00:01 +0200 Subject: parisc: Enable the ro_after_init feature This patch modifies the initial page mapping functions in the following way: During bootup the init, text and data pages will be mapped RWX and if supported, with huge pages. At final stage of the bootup, the kernel calls free_initmem() and then all pages will be remapped either R-X (for text and read-only data) or RW- (for data). The __init pages will be dropped. This reflects the behaviour of the x86 platform. Signed-off-by: Helge Deller --- arch/parisc/include/asm/cache.h | 3 -- arch/parisc/kernel/vmlinux.lds.S | 3 -- arch/parisc/mm/init.c | 67 +++++++++++++++++++++------------------- 3 files changed, 35 insertions(+), 38 deletions(-) (limited to 'arch') diff --git a/arch/parisc/include/asm/cache.h b/arch/parisc/include/asm/cache.h index 4016fe1c65a9..73ca89a47f49 100644 --- a/arch/parisc/include/asm/cache.h +++ b/arch/parisc/include/asm/cache.h @@ -24,9 +24,6 @@ #define __read_mostly __attribute__((__section__(".data..read_mostly"))) -/* Read-only memory is marked before mark_rodata_ro() is called. */ -#define __ro_after_init __read_mostly - void parisc_cache_init(void); /* initializes cache-flushing */ void disable_sr_hashing_asm(int); /* low level support for above */ void disable_sr_hashing(void); /* turns off space register hashing */ diff --git a/arch/parisc/kernel/vmlinux.lds.S b/arch/parisc/kernel/vmlinux.lds.S index a8be7a47fcc0..c3b1b9c24ede 100644 --- a/arch/parisc/kernel/vmlinux.lds.S +++ b/arch/parisc/kernel/vmlinux.lds.S @@ -18,9 +18,6 @@ *(.data..vm0.pgd) \ *(.data..vm0.pte) -/* No __ro_after_init data in the .rodata section - which will always be ro */ -#define RO_AFTER_INIT_DATA - #include /* needed for the processor specific cache alignment size */ diff --git a/arch/parisc/mm/init.c b/arch/parisc/mm/init.c index 3b0f9eab7f2c..b99bcbf1ecdb 100644 --- a/arch/parisc/mm/init.c +++ b/arch/parisc/mm/init.c @@ -345,16 +345,7 @@ static void __init setup_bootmem(void) memblock_dump_all(); } -static int __init parisc_text_address(unsigned long vaddr) -{ - static unsigned long head_ptr __initdata; - - if (!head_ptr) - head_ptr = PAGE_MASK & (unsigned long) - dereference_function_descriptor(&parisc_kernel_start); - - return core_kernel_text(vaddr) || vaddr == head_ptr; -} +static bool kernel_set_to_readonly; static void __init map_pages(unsigned long start_vaddr, unsigned long start_paddr, unsigned long size, @@ -372,10 +363,11 @@ static void __init map_pages(unsigned long start_vaddr, unsigned long vaddr; unsigned long ro_start; unsigned long ro_end; - unsigned long kernel_end; + unsigned long kernel_start, kernel_end; ro_start = __pa((unsigned long)_text); ro_end = __pa((unsigned long)&data_start); + kernel_start = __pa((unsigned long)&__init_begin); kernel_end = __pa((unsigned long)&_end); end_paddr = start_paddr + size; @@ -438,26 +430,30 @@ static void __init map_pages(unsigned long start_vaddr, pg_table = (pte_t *) __va(pg_table) + start_pte; for (tmp2 = start_pte; tmp2 < PTRS_PER_PTE; tmp2++, pg_table++) { pte_t pte; - - if (force) - pte = __mk_pte(address, pgprot); - else if (parisc_text_address(vaddr)) { - pte = __mk_pte(address, PAGE_KERNEL_EXEC); - if (address >= ro_start && address < kernel_end) - pte = pte_mkhuge(pte); + pgprot_t prot; + bool huge = false; + + if (force) { + prot = pgprot; + } else if (address < kernel_start || address >= kernel_end) { + /* outside kernel memory */ + prot = PAGE_KERNEL; + } else if (!kernel_set_to_readonly) { + /* still initializing, allow writing to RO memory */ + prot = PAGE_KERNEL_RWX; + huge = true; + } else if (address >= ro_start) { + /* Code (ro) and Data areas */ + prot = (address < ro_end) ? + PAGE_KERNEL_EXEC : PAGE_KERNEL; + huge = true; + } else { + prot = PAGE_KERNEL; } - else -#if defined(CONFIG_PARISC_PAGE_SIZE_4KB) - if (address >= ro_start && address < ro_end) { - pte = __mk_pte(address, PAGE_KERNEL_EXEC); + + pte = __mk_pte(address, prot); + if (huge) pte = pte_mkhuge(pte); - } else -#endif - { - pte = __mk_pte(address, pgprot); - if (address >= ro_start && address < kernel_end) - pte = pte_mkhuge(pte); - } if (address >= end_paddr) break; @@ -493,6 +489,12 @@ void __ref free_initmem(void) { unsigned long init_begin = (unsigned long)__init_begin; unsigned long init_end = (unsigned long)__init_end; + unsigned long kernel_end = (unsigned long)&_end; + + /* Remap kernel text and data, but do not touch init section yet. */ + kernel_set_to_readonly = true; + map_pages(init_end, __pa(init_end), kernel_end - init_end, + PAGE_KERNEL, 0); /* The init text pages are marked R-X. We have to * flush the icache and mark them RW- @@ -509,7 +511,7 @@ void __ref free_initmem(void) PAGE_KERNEL, 1); /* force the kernel to see the new TLB entries */ - __flush_tlb_range(0, init_begin, init_end); + __flush_tlb_range(0, init_begin, kernel_end); /* finally dump all the instructions which were cached, since the * pages are no-longer executable */ @@ -527,8 +529,9 @@ void mark_rodata_ro(void) { /* rodata memory was already mapped with KERNEL_RO access rights by pagetable_init() and map_pages(). No need to do additional stuff here */ - printk (KERN_INFO "Write protecting the kernel read-only data: %luk\n", - (unsigned long)(__end_rodata - __start_rodata) >> 10); + unsigned long roai_size = __end_ro_after_init - __start_ro_after_init; + + pr_info("Write protected read-only-after-init data: %luk\n", roai_size >> 10); } #endif -- cgit v1.2.3 From 271c29a17fadd3eabbfe63f13bb49dfb6c9d872d Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Fri, 10 May 2019 20:47:11 +0200 Subject: parisc: Use __ro_after_init in cache.c Signed-off-by: Helge Deller --- arch/parisc/kernel/cache.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) (limited to 'arch') diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c index 0338561968a4..a82b3eaa5398 100644 --- a/arch/parisc/kernel/cache.c +++ b/arch/parisc/kernel/cache.c @@ -29,9 +29,9 @@ #include #include -int split_tlb __read_mostly; -int dcache_stride __read_mostly; -int icache_stride __read_mostly; +int split_tlb __ro_after_init; +int dcache_stride __ro_after_init; +int icache_stride __ro_after_init; EXPORT_SYMBOL(dcache_stride); void flush_dcache_page_asm(unsigned long phys_addr, unsigned long vaddr); @@ -51,12 +51,12 @@ DEFINE_SPINLOCK(pa_tlb_flush_lock); DEFINE_SPINLOCK(pa_swapper_pg_lock); #if defined(CONFIG_64BIT) && defined(CONFIG_SMP) -int pa_serialize_tlb_flushes __read_mostly; +int pa_serialize_tlb_flushes __ro_after_init; #endif -struct pdc_cache_info cache_info __read_mostly; +struct pdc_cache_info cache_info __ro_after_init; #ifndef CONFIG_PA20 -static struct pdc_btlb_info btlb_info __read_mostly; +static struct pdc_btlb_info btlb_info __ro_after_init; #endif #ifdef CONFIG_SMP @@ -381,10 +381,10 @@ EXPORT_SYMBOL(flush_data_cache_local); EXPORT_SYMBOL(flush_kernel_icache_range_asm); #define FLUSH_THRESHOLD 0x80000 /* 0.5MB */ -static unsigned long parisc_cache_flush_threshold __read_mostly = FLUSH_THRESHOLD; +static unsigned long parisc_cache_flush_threshold __ro_after_init = FLUSH_THRESHOLD; #define FLUSH_TLB_THRESHOLD (16*1024) /* 16 KiB minimum TLB threshold */ -static unsigned long parisc_tlb_flush_threshold __read_mostly = FLUSH_TLB_THRESHOLD; +static unsigned long parisc_tlb_flush_threshold __ro_after_init = FLUSH_TLB_THRESHOLD; void __init parisc_setup_cache_timing(void) { -- cgit v1.2.3 From 9aa8848a751fec5f655f4409875baaee1ca3e3e8 Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Fri, 10 May 2019 20:49:16 +0200 Subject: parisc: Use __ro_after_init in drivers.c Signed-off-by: Helge Deller --- arch/parisc/kernel/drivers.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/parisc/kernel/drivers.c b/arch/parisc/kernel/drivers.c index 15e7b3be7b6b..00a181f1ecc6 100644 --- a/arch/parisc/kernel/drivers.c +++ b/arch/parisc/kernel/drivers.c @@ -41,7 +41,7 @@ #include /* See comments in include/asm-parisc/pci.h */ -const struct dma_map_ops *hppa_dma_ops __read_mostly; +const struct dma_map_ops *hppa_dma_ops __ro_after_init; EXPORT_SYMBOL(hppa_dma_ops); static struct device root = { -- cgit v1.2.3 From 1b69085d4fcfd1df67d86a553c522fa1cb7603b4 Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Fri, 10 May 2019 20:50:16 +0200 Subject: parisc: Use __ro_after_init in firmware.c Signed-off-by: Helge Deller --- arch/parisc/kernel/firmware.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/parisc/kernel/firmware.c b/arch/parisc/kernel/firmware.c index 7a17551ea31e..f01e102bbfa2 100644 --- a/arch/parisc/kernel/firmware.c +++ b/arch/parisc/kernel/firmware.c @@ -87,7 +87,7 @@ extern unsigned long pdc_result2[NUM_PDC_RESULT]; /* Firmware needs to be initially set to narrow to determine the * actual firmware width. */ -int parisc_narrow_firmware __read_mostly = 1; +int parisc_narrow_firmware __ro_after_init = 1; #endif /* On most currently-supported platforms, IODC I/O calls are 32-bit calls -- cgit v1.2.3 From dc1b3c0d50eae30c4588f2146fe41b49584e50fb Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Fri, 10 May 2019 20:50:46 +0200 Subject: parisc: Use __ro_after_init in head.S Signed-off-by: Helge Deller --- arch/parisc/kernel/head.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/parisc/kernel/head.S b/arch/parisc/kernel/head.S index d12de2a13753..951a339369dd 100644 --- a/arch/parisc/kernel/head.S +++ b/arch/parisc/kernel/head.S @@ -376,7 +376,7 @@ smp_slave_stext: ENDPROC(parisc_kernel_start) #ifndef CONFIG_64BIT - .section .data..read_mostly + .section .data..ro_after_init .align 4 .export $global$,data -- cgit v1.2.3 From 7c1952b4be68a40d2283b16d8236cb8d2af1272f Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Fri, 10 May 2019 20:51:44 +0200 Subject: parisc: Use __ro_after_init in inventory.c Signed-off-by: Helge Deller --- arch/parisc/kernel/inventory.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'arch') diff --git a/arch/parisc/kernel/inventory.c b/arch/parisc/kernel/inventory.c index 6f2d611347a1..3f4a91c0b805 100644 --- a/arch/parisc/kernel/inventory.c +++ b/arch/parisc/kernel/inventory.c @@ -39,12 +39,12 @@ */ #undef DEBUG_PAT -int pdc_type __read_mostly = PDC_TYPE_ILLEGAL; +int pdc_type __ro_after_init = PDC_TYPE_ILLEGAL; /* cell number and location (PAT firmware only) */ -unsigned long parisc_cell_num __read_mostly; -unsigned long parisc_cell_loc __read_mostly; -unsigned long parisc_pat_pdc_cap __read_mostly; +unsigned long parisc_cell_num __ro_after_init; +unsigned long parisc_cell_loc __ro_after_init; +unsigned long parisc_pat_pdc_cap __ro_after_init; void __init setup_pdc(void) -- cgit v1.2.3 From 874b051923dd757adfeacc71ea2f7f0cfbf267c4 Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Fri, 10 May 2019 20:52:36 +0200 Subject: parisc: Use __ro_after_init in pci.c Signed-off-by: Helge Deller --- arch/parisc/kernel/pci.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'arch') diff --git a/arch/parisc/kernel/pci.c b/arch/parisc/kernel/pci.c index ae684ac6efb6..bc41ca243cfe 100644 --- a/arch/parisc/kernel/pci.c +++ b/arch/parisc/kernel/pci.c @@ -45,14 +45,14 @@ * #define pci_post_reset_delay 50 */ -struct pci_port_ops *pci_port __read_mostly; -struct pci_bios_ops *pci_bios __read_mostly; +struct pci_port_ops *pci_port __ro_after_init; +struct pci_bios_ops *pci_bios __ro_after_init; -static int pci_hba_count __read_mostly; +static int pci_hba_count __ro_after_init; /* parisc_pci_hba used by pci_port->in/out() ops to lookup bus data. */ #define PCI_HBA_MAX 32 -static struct pci_hba_data *parisc_pci_hba[PCI_HBA_MAX] __read_mostly; +static struct pci_hba_data *parisc_pci_hba[PCI_HBA_MAX] __ro_after_init; /******************************************************************** -- cgit v1.2.3 From 67266fd48f0f6cb42838aeac2ef55417640ad1b5 Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Fri, 10 May 2019 20:53:46 +0200 Subject: parisc: Use __ro_after_init in perf_images.h Signed-off-by: Helge Deller --- arch/parisc/kernel/perf_images.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch') diff --git a/arch/parisc/kernel/perf_images.h b/arch/parisc/kernel/perf_images.h index 7fef9644df47..c108fee989d9 100644 --- a/arch/parisc/kernel/perf_images.h +++ b/arch/parisc/kernel/perf_images.h @@ -25,7 +25,7 @@ #define PCXU_IMAGE_SIZE 584 -static uint32_t onyx_images[][PCXU_IMAGE_SIZE/sizeof(uint32_t)] __read_mostly = { +static uint32_t onyx_images[][PCXU_IMAGE_SIZE/sizeof(uint32_t)] __ro_after_init = { /* * CPI: * @@ -2093,7 +2093,7 @@ static uint32_t onyx_images[][PCXU_IMAGE_SIZE/sizeof(uint32_t)] __read_mostly = }; #define PCXW_IMAGE_SIZE 576 -static uint32_t cuda_images[][PCXW_IMAGE_SIZE/sizeof(uint32_t)] __read_mostly = { +static uint32_t cuda_images[][PCXW_IMAGE_SIZE/sizeof(uint32_t)] __ro_after_init = { /* * CPI: FROM CPI.IDF (Image 0) * -- cgit v1.2.3 From 7e4c65bf0637c089d8981ac7e99081a57ffbcdbc Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Fri, 10 May 2019 20:54:31 +0200 Subject: parisc: Use __ro_after_init in process.c Signed-off-by: Helge Deller --- arch/parisc/kernel/process.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c index 97c206734e24..89e4f4497ffb 100644 --- a/arch/parisc/kernel/process.c +++ b/arch/parisc/kernel/process.c @@ -192,7 +192,7 @@ int dump_task_fpu (struct task_struct *tsk, elf_fpregset_t *r) * QEMU idle the host too. */ -int running_on_qemu __read_mostly; +int running_on_qemu __ro_after_init; EXPORT_SYMBOL(running_on_qemu); void __cpuidle arch_cpu_idle_dead(void) -- cgit v1.2.3 From d98883690b7bc5faab98795dff694549e4c60556 Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Fri, 10 May 2019 20:55:08 +0200 Subject: parisc: Use __ro_after_init in processor.c Signed-off-by: Helge Deller --- arch/parisc/kernel/processor.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch') diff --git a/arch/parisc/kernel/processor.c b/arch/parisc/kernel/processor.c index e0a81dedc366..e715871cd4ac 100644 --- a/arch/parisc/kernel/processor.c +++ b/arch/parisc/kernel/processor.c @@ -43,10 +43,10 @@ #include /* for struct irq_region */ #include -struct system_cpuinfo_parisc boot_cpu_data __read_mostly; +struct system_cpuinfo_parisc boot_cpu_data __ro_after_init; EXPORT_SYMBOL(boot_cpu_data); #ifdef CONFIG_PA8X00 -int _parisc_requires_coherency __read_mostly; +int _parisc_requires_coherency __ro_after_init; EXPORT_SYMBOL(_parisc_requires_coherency); #endif -- cgit v1.2.3 From 34589df6338afc75208cd3f9b612c1ae7738bbd0 Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Fri, 10 May 2019 20:55:31 +0200 Subject: parisc: Use __ro_after_init in time.c Signed-off-by: Helge Deller --- arch/parisc/kernel/time.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/parisc/kernel/time.c b/arch/parisc/kernel/time.c index a1e772f909cb..04508158815c 100644 --- a/arch/parisc/kernel/time.c +++ b/arch/parisc/kernel/time.c @@ -40,7 +40,7 @@ #include -static unsigned long clocktick __read_mostly; /* timer cycles per tick */ +static unsigned long clocktick __ro_after_init; /* timer cycles per tick */ /* * We keep time on PA-RISC Linux by using the Interval Timer which is -- cgit v1.2.3 From 47293774c49c174c9863a60a757b825299ddf649 Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Fri, 10 May 2019 20:55:51 +0200 Subject: parisc: Use __ro_after_init in unwind.c Signed-off-by: Helge Deller --- arch/parisc/kernel/unwind.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/parisc/kernel/unwind.c b/arch/parisc/kernel/unwind.c index 2d14f17838d2..87ae476d1c4f 100644 --- a/arch/parisc/kernel/unwind.c +++ b/arch/parisc/kernel/unwind.c @@ -40,7 +40,7 @@ static DEFINE_SPINLOCK(unwind_lock); * we can call unwind_init as early in the bootup process as * possible (before the slab allocator is initialized) */ -static struct unwind_table kernel_unwind_table __read_mostly; +static struct unwind_table kernel_unwind_table __ro_after_init; static LIST_HEAD(unwind_tables); static inline const struct unwind_table_entry * -- cgit v1.2.3 From 4e617c86ba9be5211643e53f5f69d1195c956d68 Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Fri, 10 May 2019 20:56:16 +0200 Subject: parisc: Use __ro_after_init in init.c Signed-off-by: Helge Deller --- arch/parisc/mm/init.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'arch') diff --git a/arch/parisc/mm/init.c b/arch/parisc/mm/init.c index b99bcbf1ecdb..5a68185295a9 100644 --- a/arch/parisc/mm/init.c +++ b/arch/parisc/mm/init.c @@ -66,7 +66,7 @@ static struct resource pdcdata_resource = { .flags = IORESOURCE_BUSY | IORESOURCE_MEM, }; -static struct resource sysram_resources[MAX_PHYSMEM_RANGES] __read_mostly; +static struct resource sysram_resources[MAX_PHYSMEM_RANGES] __ro_after_init; /* The following array is initialized from the firmware specific * information retrieved in kernel/inventory.c. @@ -557,11 +557,11 @@ void mark_rodata_ro(void) #define SET_MAP_OFFSET(x) ((void *)(((unsigned long)(x) + VM_MAP_OFFSET) \ & ~(VM_MAP_OFFSET-1))) -void *parisc_vmalloc_start __read_mostly; +void *parisc_vmalloc_start __ro_after_init; EXPORT_SYMBOL(parisc_vmalloc_start); #ifdef CONFIG_PA11 -unsigned long pcxl_dma_start __read_mostly; +unsigned long pcxl_dma_start __ro_after_init; #endif void __init mem_init(void) @@ -635,7 +635,7 @@ void __init mem_init(void) #endif } -unsigned long *empty_zero_page __read_mostly; +unsigned long *empty_zero_page __ro_after_init; EXPORT_SYMBOL(empty_zero_page); /* -- cgit v1.2.3