From: Will Deacon Date: Wed, 23 Nov 2011 12:26:25 +0000 (+0000) Subject: ARM: SMP: use idmap_pgd for mapping MMU enable during secondary booting X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=4e8ee7de227e3ab9a72040b448ad728c5428a042;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git ARM: SMP: use idmap_pgd for mapping MMU enable during secondary booting The ARM SMP booting code allocates a temporary set of page tables containing an identity mapping of the kernel image and provides this to secondary CPUs for initial booting. In reality, we only need to include the __turn_mmu_on function in the identity mapping since the rest of the kernel is executing from virtual addresses after this point. This patch adds __turn_mmu_on to the .idmap.text section, allowing the SMP booting code to use the idmap_pgd directly and not have to populate its own set of page table. As a result of this patch, we can make the identity_mapping_add function static (since it is only used within mm/idmap.c) and also remove the identity_mapping_del function. The identity map population is moved to an early initcall so that it is setup in time for secondary CPU bringup. Reviewed-by: Catalin Marinas Signed-off-by: Will Deacon --- diff --git a/arch/arm/include/asm/idmap.h b/arch/arm/include/asm/idmap.h index 62e3d19c9ad7..bf863edb517d 100644 --- a/arch/arm/include/asm/idmap.h +++ b/arch/arm/include/asm/idmap.h @@ -9,9 +9,6 @@ extern pgd_t *idmap_pgd; -void identity_mapping_add(pgd_t *, unsigned long, unsigned long); -void identity_mapping_del(pgd_t *, unsigned long, unsigned long); - void setup_mm_for_reboot(void); #endif /* __ASM_IDMAP_H */ diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S index 43e3aa3b0573..64e9943ea4f0 100644 --- a/arch/arm/kernel/head.S +++ b/arch/arm/kernel/head.S @@ -398,7 +398,8 @@ ENDPROC(__enable_mmu) * other registers depend on the function called upon completion */ .align 5 -__turn_mmu_on: + .pushsection .idmap.text, "ax" +ENTRY(__turn_mmu_on) mov r0, r0 mcr p15, 0, r0, c1, c0, 0 @ write control reg mrc p15, 0, r3, c0, c0, 0 @ read id reg @@ -407,6 +408,7 @@ __turn_mmu_on: mov pc, r3 __turn_mmu_on_end: ENDPROC(__turn_mmu_on) + .popsection #ifdef CONFIG_SMP_ON_UP diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 8afadda37459..76ff28d87bf3 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -62,7 +62,6 @@ int __cpuinit __cpu_up(unsigned int cpu) { struct cpuinfo_arm *ci = &per_cpu(cpu_data, cpu); struct task_struct *idle = ci->idle; - pgd_t *pgd; int ret; /* @@ -84,30 +83,12 @@ int __cpuinit __cpu_up(unsigned int cpu) init_idle(idle, cpu); } - /* - * Allocate initial page tables to allow the new CPU to - * enable the MMU safely. This essentially means a set - * of our "standard" page tables, with the addition of - * a 1:1 mapping for the physical address of the kernel. - */ - pgd = pgd_alloc(&init_mm); - if (!pgd) - return -ENOMEM; - - if (PHYS_OFFSET != PAGE_OFFSET) { -#ifndef CONFIG_HOTPLUG_CPU - identity_mapping_add(pgd, __pa(__init_begin), __pa(__init_end)); -#endif - identity_mapping_add(pgd, __pa(_stext), __pa(_etext)); - identity_mapping_add(pgd, __pa(_sdata), __pa(_edata)); - } - /* * We need to tell the secondary core where to find * its stack and the page tables. */ secondary_data.stack = task_stack_page(idle) + THREAD_START_SP; - secondary_data.pgdir = virt_to_phys(pgd); + secondary_data.pgdir = virt_to_phys(idmap_pgd); secondary_data.swapper_pg_dir = virt_to_phys(swapper_pg_dir); __cpuc_flush_dcache_area(&secondary_data, sizeof(secondary_data)); outer_clean_range(__pa(&secondary_data), __pa(&secondary_data + 1)); @@ -143,16 +124,6 @@ int __cpuinit __cpu_up(unsigned int cpu) secondary_data.stack = NULL; secondary_data.pgdir = 0; - if (PHYS_OFFSET != PAGE_OFFSET) { -#ifndef CONFIG_HOTPLUG_CPU - identity_mapping_del(pgd, __pa(__init_begin), __pa(__init_end)); -#endif - identity_mapping_del(pgd, __pa(_stext), __pa(_etext)); - identity_mapping_del(pgd, __pa(_sdata), __pa(_edata)); - } - - pgd_free(&init_mm, pgd); - return ret; } diff --git a/arch/arm/mm/idmap.c b/arch/arm/mm/idmap.c index b01760e6da18..660f1bc68f99 100644 --- a/arch/arm/mm/idmap.c +++ b/arch/arm/mm/idmap.c @@ -32,7 +32,7 @@ static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end, } while (pud++, addr = next, addr != end); } -void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end) +static void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end) { unsigned long prot, next; @@ -47,36 +47,6 @@ void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end) } while (pgd++, addr = next, addr != end); } -#ifdef CONFIG_SMP -static void idmap_del_pmd(pud_t *pud, unsigned long addr, unsigned long end) -{ - pmd_t *pmd = pmd_offset(pud, addr); - pmd_clear(pmd); -} - -static void idmap_del_pud(pgd_t *pgd, unsigned long addr, unsigned long end) -{ - pud_t *pud = pud_offset(pgd, addr); - unsigned long next; - - do { - next = pud_addr_end(addr, end); - idmap_del_pmd(pud, addr, next); - } while (pud++, addr = next, addr != end); -} - -void identity_mapping_del(pgd_t *pgd, unsigned long addr, unsigned long end) -{ - unsigned long next; - - pgd += pgd_index(addr); - do { - next = pgd_addr_end(addr, end); - idmap_del_pud(pgd, addr, next); - } while (pgd++, addr = next, addr != end); -} -#endif - extern char __idmap_text_start[], __idmap_text_end[]; static int __init init_static_idmap(void) @@ -97,7 +67,7 @@ static int __init init_static_idmap(void) return 0; } -arch_initcall(init_static_idmap); +early_initcall(init_static_idmap); /* * In order to soft-boot, we need to switch to a 1:1 mapping for the