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Commit eb08375e authored by Jonathan Austin's avatar Jonathan Austin
Browse files

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: default avatarJonathan Austin <jonathan.austin@arm.com>
Reviewed-by: default avatarWill Deacon <will.deacon@arm.com>
CC: Nicolas Pitre <nico@linaro.org>
parent 9a271567

arch/arm/include/asm/smp.h

+4 −1
Original line number Diff line number Diff line
@@ -65,7 +65,10 @@ asmlinkage void secondary_start_kernel(void); 
 * Initial data for bringing up a secondary CPU.

 */

struct secondary_data {

	union {

		unsigned long mpu_rgn_szr;

		unsigned long pgdir;

	};

	unsigned long swapper_pg_dir;

	void *stack;

};

arch/arm/kernel/head-nommu.S

+7 −0
Original line number Diff line number Diff line
@@ -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	)

arch/arm/kernel/smp.c

+6 −2
Original line number Diff line number Diff line
@@ -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;

}