Commit 4e8ee7de authored by Will Deacon's avatar Will Deacon

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: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 72662e01
...@@ -9,9 +9,6 @@ ...@@ -9,9 +9,6 @@
extern pgd_t *idmap_pgd; 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); void setup_mm_for_reboot(void);
#endif /* __ASM_IDMAP_H */ #endif /* __ASM_IDMAP_H */
...@@ -398,7 +398,8 @@ ENDPROC(__enable_mmu) ...@@ -398,7 +398,8 @@ ENDPROC(__enable_mmu)
* other registers depend on the function called upon completion * other registers depend on the function called upon completion
*/ */
.align 5 .align 5
__turn_mmu_on: .pushsection .idmap.text, "ax"
ENTRY(__turn_mmu_on)
mov r0, r0 mov r0, r0
mcr p15, 0, r0, c1, c0, 0 @ write control reg mcr p15, 0, r0, c1, c0, 0 @ write control reg
mrc p15, 0, r3, c0, c0, 0 @ read id reg mrc p15, 0, r3, c0, c0, 0 @ read id reg
...@@ -407,6 +408,7 @@ __turn_mmu_on: ...@@ -407,6 +408,7 @@ __turn_mmu_on:
mov pc, r3 mov pc, r3
__turn_mmu_on_end: __turn_mmu_on_end:
ENDPROC(__turn_mmu_on) ENDPROC(__turn_mmu_on)
.popsection
#ifdef CONFIG_SMP_ON_UP #ifdef CONFIG_SMP_ON_UP
......
...@@ -62,7 +62,6 @@ int __cpuinit __cpu_up(unsigned int cpu) ...@@ -62,7 +62,6 @@ int __cpuinit __cpu_up(unsigned int cpu)
{ {
struct cpuinfo_arm *ci = &per_cpu(cpu_data, cpu); struct cpuinfo_arm *ci = &per_cpu(cpu_data, cpu);
struct task_struct *idle = ci->idle; struct task_struct *idle = ci->idle;
pgd_t *pgd;
int ret; int ret;
/* /*
...@@ -84,30 +83,12 @@ int __cpuinit __cpu_up(unsigned int cpu) ...@@ -84,30 +83,12 @@ int __cpuinit __cpu_up(unsigned int cpu)
init_idle(idle, 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 * We need to tell the secondary core where to find
* its stack and the page tables. * its stack and the page tables.
*/ */
secondary_data.stack = task_stack_page(idle) + THREAD_START_SP; 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); secondary_data.swapper_pg_dir = virt_to_phys(swapper_pg_dir);
__cpuc_flush_dcache_area(&secondary_data, sizeof(secondary_data)); __cpuc_flush_dcache_area(&secondary_data, sizeof(secondary_data));
outer_clean_range(__pa(&secondary_data), __pa(&secondary_data + 1)); outer_clean_range(__pa(&secondary_data), __pa(&secondary_data + 1));
...@@ -143,16 +124,6 @@ int __cpuinit __cpu_up(unsigned int cpu) ...@@ -143,16 +124,6 @@ int __cpuinit __cpu_up(unsigned int cpu)
secondary_data.stack = NULL; secondary_data.stack = NULL;
secondary_data.pgdir = 0; 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; return ret;
} }
......
...@@ -32,7 +32,7 @@ static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end, ...@@ -32,7 +32,7 @@ static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
} while (pud++, addr = next, addr != 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; unsigned long prot, next;
...@@ -47,36 +47,6 @@ void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end) ...@@ -47,36 +47,6 @@ void identity_mapping_add(pgd_t *pgd, unsigned long addr, unsigned long end)
} while (pgd++, addr = next, addr != 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[]; extern char __idmap_text_start[], __idmap_text_end[];
static int __init init_static_idmap(void) static int __init init_static_idmap(void)
...@@ -97,7 +67,7 @@ static int __init init_static_idmap(void) ...@@ -97,7 +67,7 @@ static int __init init_static_idmap(void)
return 0; 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 * In order to soft-boot, we need to switch to a 1:1 mapping for the
......
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