From 8903826d0cd99aed9267e792d38284cf3092042b Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 30 Sep 2011 11:43:29 +0100 Subject: ARM: idmap: populate identity map pgd at init time using .init.text When disabling and re-enabling the MMU, it is necessary to take out an identity mapping for the code that manipulates the SCTLR in order to avoid it disappearing from under our feet. This is useful when soft rebooting and returning from CPU suspend. This patch allocates a set of page tables during boot and populates them with an identity mapping for the .idmap.text section. This means that users of the identity map do not need to manage their own pgd and can instead annotate their functions with __idmap or, in the case of assembly code, place them in the correct section. Acked-by: Dave Martin Reviewed-by: Catalin Marinas Tested-by: Lorenzo Pieralisi Signed-off-by: Will Deacon --- arch/arm/kernel/smp.c | 1 + arch/arm/kernel/vmlinux.lds.S | 7 +++++++ 2 files changed, 8 insertions(+) (limited to 'arch/arm/kernel') diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index ef5640b9e218..8afadda37459 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -31,6 +31,7 @@ #include #include #include +#include #include #include #include diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S index 20b3041e0860..f76e75548670 100644 --- a/arch/arm/kernel/vmlinux.lds.S +++ b/arch/arm/kernel/vmlinux.lds.S @@ -13,6 +13,12 @@ *(.proc.info.init) \ VMLINUX_SYMBOL(__proc_info_end) = .; +#define IDMAP_TEXT \ + ALIGN_FUNCTION(); \ + VMLINUX_SYMBOL(__idmap_text_start) = .; \ + *(.idmap.text) \ + VMLINUX_SYMBOL(__idmap_text_end) = .; + #ifdef CONFIG_HOTPLUG_CPU #define ARM_CPU_DISCARD(x) #define ARM_CPU_KEEP(x) x @@ -92,6 +98,7 @@ SECTIONS SCHED_TEXT LOCK_TEXT KPROBES_TEXT + IDMAP_TEXT #ifdef CONFIG_MMU *(.fixup) #endif -- cgit v1.2.2 From e6eadc67873d5f363c864cd7723104e7d47dcb44 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Tue, 15 Nov 2011 11:11:19 +0000 Subject: ARM: suspend: use idmap_pgd instead of suspend_pgd The ARM CPU suspend code requires cpu_resume_mmu to be identity mapped in order to re-enable the MMU when coming out of suspend. Currently, this is accomplished by maintaining a suspend_pgd with the relevant mapping put in place at init time. This patch replaces the use of suspend_pgd with the new idmap_pgd. cpu_resume_mmu is placed in the .idmap.text section so that it is included in the identity map. Reviewed-by: Catalin Marinas Acked-by: Dave Martin Tested-by: Lorenzo Pieralisi Signed-off-by: Will Deacon --- arch/arm/kernel/sleep.S | 2 ++ arch/arm/kernel/suspend.c | 18 +++--------------- 2 files changed, 5 insertions(+), 15 deletions(-) (limited to 'arch/arm/kernel') diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S index 020e99c845e7..9e64231c8cfe 100644 --- a/arch/arm/kernel/sleep.S +++ b/arch/arm/kernel/sleep.S @@ -54,6 +54,7 @@ ENDPROC(cpu_suspend_abort) * r0 = control register value */ .align 5 + .pushsection .idmap.text,"ax" ENTRY(cpu_resume_mmu) ldr r3, =cpu_resume_after_mmu mcr p15, 0, r0, c1, c0, 0 @ turn on MMU, I-cache, etc @@ -62,6 +63,7 @@ ENTRY(cpu_resume_mmu) mov r0, r0 mov pc, r3 @ jump to virtual address ENDPROC(cpu_resume_mmu) + .popsection cpu_resume_after_mmu: bl cpu_init @ restore the und/abt/irq banked regs mov r0, #0 @ return zero on success diff --git a/arch/arm/kernel/suspend.c b/arch/arm/kernel/suspend.c index 93a22d282c16..1794cc3b0f18 100644 --- a/arch/arm/kernel/suspend.c +++ b/arch/arm/kernel/suspend.c @@ -1,13 +1,12 @@ #include +#include #include #include #include #include #include -static pgd_t *suspend_pgd; - extern int __cpu_suspend(unsigned long, int (*)(unsigned long)); extern void cpu_resume_mmu(void); @@ -21,7 +20,7 @@ void __cpu_suspend_save(u32 *ptr, u32 ptrsz, u32 sp, u32 *save_ptr) *save_ptr = virt_to_phys(ptr); /* This must correspond to the LDM in cpu_resume() assembly */ - *ptr++ = virt_to_phys(suspend_pgd); + *ptr++ = virt_to_phys(idmap_pgd); *ptr++ = sp; *ptr++ = virt_to_phys(cpu_do_resume); @@ -42,7 +41,7 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) struct mm_struct *mm = current->active_mm; int ret; - if (!suspend_pgd) + if (!idmap_pgd) return -EINVAL; /* @@ -59,14 +58,3 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) return ret; } - -static int __init cpu_suspend_init(void) -{ - suspend_pgd = pgd_alloc(&init_mm); - if (suspend_pgd) { - unsigned long addr = virt_to_phys(cpu_resume_mmu); - identity_mapping_add(suspend_pgd, addr, addr + SECTION_SIZE); - } - return suspend_pgd ? 0 : -ENOMEM; -} -core_initcall(cpu_suspend_init); -- cgit v1.2.2 From 72662e01088394577be4a3f14da94cf87bea2591 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Wed, 23 Nov 2011 12:03:27 +0000 Subject: ARM: head.S: only include __turn_mmu_on in the initial identity mapping __create_page_tables identity maps the region of memory from __enable_mmu to the end of __turn_mmu_on. In preparation for including __turn_mmu_on in the .idmap.text section, this patch modifies the identity mapping so that it only includes the __turn_mmu_on code. Reviewed-by: Catalin Marinas Signed-off-by: Will Deacon --- arch/arm/kernel/head.S | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) (limited to 'arch/arm/kernel') diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S index 566c54c2a1fe..43e3aa3b0573 100644 --- a/arch/arm/kernel/head.S +++ b/arch/arm/kernel/head.S @@ -170,11 +170,11 @@ __create_page_tables: * Create identity mapping to cater for __enable_mmu. * This identity mapping will be removed by paging_init(). */ - adr r0, __enable_mmu_loc + adr r0, __turn_mmu_on_loc ldmia r0, {r3, r5, r6} sub r0, r0, r3 @ virt->phys offset - add r5, r5, r0 @ phys __enable_mmu - add r6, r6, r0 @ phys __enable_mmu_end + add r5, r5, r0 @ phys __turn_mmu_on + add r6, r6, r0 @ phys __turn_mmu_on_end mov r5, r5, lsr #SECTION_SHIFT mov r6, r6, lsr #SECTION_SHIFT @@ -287,10 +287,10 @@ __create_page_tables: ENDPROC(__create_page_tables) .ltorg .align -__enable_mmu_loc: +__turn_mmu_on_loc: .long . - .long __enable_mmu - .long __enable_mmu_end + .long __turn_mmu_on + .long __turn_mmu_on_end #if defined(CONFIG_SMP) __CPUINIT @@ -405,7 +405,7 @@ __turn_mmu_on: mov r3, r3 mov r3, r13 mov pc, r3 -__enable_mmu_end: +__turn_mmu_on_end: ENDPROC(__turn_mmu_on) -- cgit v1.2.2 From 4e8ee7de227e3ab9a72040b448ad728c5428a042 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Wed, 23 Nov 2011 12:26:25 +0000 Subject: 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 --- arch/arm/kernel/head.S | 4 +++- arch/arm/kernel/smp.c | 31 +------------------------------ 2 files changed, 4 insertions(+), 31 deletions(-) (limited to 'arch/arm/kernel') 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; } -- cgit v1.2.2