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ARM: mpu: add MPU initialisation for secondary cores 

The MPU initialisation on the primary core is performed in two stages, one
minimal stage to ensure the CPU can boot and a second one after
sanity_check_meminfo. As the memory configuration is known by the time we
boot secondary cores only a single step is necessary, provided the values
for DRSR are passed to secondaries.

This patch implements this arrangement. The configuration generated for the
MPU regions is made available to the secondary core, which can then use the
asm MPU intialisation code to program a complete region configuration.

This is necessary for SMP configurations without an MMU, as the MPU
initialisation is the only way to ensure that memory is specified as
'shared'.

Signed-off-by: Jonathan Austin <jonathan.austin@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
CC: Nicolas Pitre <nico@linaro.org>
This commit is contained in:
Jonathan Austin 2013-02-22 18:51:30 +00:00
parent 9a271567fe
commit eb08375ea6
3 changed files with 17 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
arch/arm/include/asm/smp.h
View File

@ -65,7 +65,10 @@ asmlinkage void secondary_start_kernel(void);
* Initial data for bringing up a secondary CPU.
*/
struct secondary_data {
unsigned long pgdir;
union {
unsigned long mpu_rgn_szr;
unsigned long pgdir;
};
unsigned long swapper_pg_dir;
void *stack;
};

7
arch/arm/kernel/head-nommu.S
View File

@ -107,6 +107,13 @@ ENTRY(secondary_startup)
adr r4, __secondary_data
ldmia r4, {r7, r12}
#ifdef CONFIG_ARM_MPU
/* Use MPU region info supplied by __cpu_up */
ldr r6, [r7] @ get secondary_data.mpu_szr
bl __setup_mpu @ Initialize the MPU
#endif
adr lr, BSYM(__after_proc_init) @ return address
mov r13, r12 @ __secondary_switched address
ARM( add pc, r10, #PROCINFO_INITFUNC )

8
arch/arm/kernel/smp.c
View File

@ -45,6 +45,7 @@
#include <asm/smp_plat.h>
#include <asm/virt.h>
#include <asm/mach/arch.h>
#include <asm/mpu.h>
/*
* as from 2.5, kernels no longer have an init_tasks structure
@ -87,6 +88,10 @@ int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *idle)
* its stack and the page tables.
*/
secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
#ifdef CONFIG_ARM_MPU
secondary_data.mpu_rgn_szr = mpu_rgn_info.rgns[MPU_RAM_REGION].drsr;
#endif
#ifdef CONFIG_MMU
secondary_data.pgdir = virt_to_phys(idmap_pgd);
secondary_data.swapper_pg_dir = virt_to_phys(swapper_pg_dir);
@ -114,9 +119,8 @@ int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *idle)
pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
}
secondary_data.stack = NULL;
secondary_data.pgdir = 0;
memset(&secondary_data, 0, sizeof(secondary_data));
return ret;
}