mirror of https://gitee.com/openkylin/linux.git
ARM: mpu: add early bring-up code for the ARMv7 PMSA-compliant MPU
This patch adds initial support for using the MPU, which is necessary for SMP operation on PMSAv7 processors because it is the only way to ensure memory is shared. This is an initial patch and full SMP support is added later in this series. The setup of the MPU is performed in a way analagous to that for the MMU: Very early initialisation before the C environment is brought up, followed by a sanity check and more complete initialisation in C. This patch provides the simplest possible memory region configuration: MPU_PROBE_REGION: Reserved for probing MPU details, not enabled MPU_BG_REGION: A 'background' region that specifies all memory strongly ordered MPU_RAM_REGION: A single shared, cacheable, normal region for the valid RAM. In this early initialisation code we simply map the whole of the address space with the BG_REGION and (at least) the kernel with the RAM_REGION. The MPU has region alignment constraints that require us to round past the end of the kernel. As region 2 has a higher priority than region 1, it overrides the strongly- ordered behaviour for RAM only. Subsequent patches will add more complete initialisation from the C-world and support for bringing up secondary CPUs. Signed-off-by: Jonathan Austin <jonathan.austin@arm.com> Reviewed-by: Will Deacon <will.deacon@arm.com> CC: Hyok S. Choi <hyok.choi@samsung.com>
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Jonathan Austin
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a2b45b0da8
commit
67c9845bea
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@ -50,6 +50,9 @@
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/* Maximum number of regions Linux is interested in */
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#define MPU_MAX_REGIONS 16
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#define MPU_DATA_SIDE 0
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#define MPU_INSTR_SIDE 1
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#ifndef __ASSEMBLY__
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struct mpu_rgn {
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@ -17,9 +17,11 @@
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#include <asm/assembler.h>
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#include <asm/ptrace.h>
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#include <asm/asm-offsets.h>
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#include <asm/memory.h>
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#include <asm/cp15.h>
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#include <asm/thread_info.h>
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#include <asm/v7m.h>
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#include <asm/mpu.h>
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/*
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* Kernel startup entry point.
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@ -63,6 +65,17 @@ ENTRY(stext)
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movs r10, r5 @ invalid processor (r5=0)?
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beq __error_p @ yes, error 'p'
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#ifdef CONFIG_ARM_MPU
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/* Calculate the size of a region covering just the kernel */
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ldr r5, =PHYS_OFFSET @ Region start: PHYS_OFFSET
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ldr r6, =(_end) @ Cover whole kernel
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sub r6, r6, r5 @ Minimum size of region to map
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clz r6, r6 @ Region size must be 2^N...
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rsb r6, r6, #31 @ ...so round up region size
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lsl r6, r6, #MPU_RSR_SZ @ Put size in right field
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orr r6, r6, #(1 << MPU_RSR_EN) @ Set region enabled bit
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bl __setup_mpu
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#endif
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ldr r13, =__mmap_switched @ address to jump to after
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@ initialising sctlr
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adr lr, BSYM(1f) @ return (PIC) address
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@ -147,4 +160,78 @@ __after_proc_init:
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ENDPROC(__after_proc_init)
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.ltorg
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#ifdef CONFIG_ARM_MPU
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/* Set which MPU region should be programmed */
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.macro set_region_nr tmp, rgnr
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mov \tmp, \rgnr @ Use static region numbers
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mcr p15, 0, \tmp, c6, c2, 0 @ Write RGNR
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.endm
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/* Setup a single MPU region, either D or I side (D-side for unified) */
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.macro setup_region bar, acr, sr, side = MPU_DATA_SIDE
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mcr p15, 0, \bar, c6, c1, (0 + \side) @ I/DRBAR
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mcr p15, 0, \acr, c6, c1, (4 + \side) @ I/DRACR
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mcr p15, 0, \sr, c6, c1, (2 + \side) @ I/DRSR
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.endm
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/*
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* Setup the MPU and initial MPU Regions. We create the following regions:
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* Region 0: Use this for probing the MPU details, so leave disabled.
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* Region 1: Background region - covers the whole of RAM as strongly ordered
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* Region 2: Normal, Shared, cacheable for RAM. From PHYS_OFFSET, size from r6
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*
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* r6: Value to be written to DRSR (and IRSR if required) for MPU_RAM_REGION
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*/
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ENTRY(__setup_mpu)
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/* Probe for v7 PMSA compliance */
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mrc p15, 0, r0, c0, c1, 4 @ Read ID_MMFR0
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and r0, r0, #(MMFR0_PMSA) @ PMSA field
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teq r0, #(MMFR0_PMSAv7) @ PMSA v7
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bne __error_p @ Fail: ARM_MPU on NOT v7 PMSA
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/* Determine whether the D/I-side memory map is unified. We set the
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* flags here and continue to use them for the rest of this function */
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mrc p15, 0, r0, c0, c0, 4 @ MPUIR
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ands r5, r0, #MPUIR_DREGION_SZMASK @ 0 size d region => No MPU
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beq __error_p @ Fail: ARM_MPU and no MPU
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tst r0, #MPUIR_nU @ MPUIR_nU = 0 for unified
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/* Setup second region first to free up r6 */
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set_region_nr r0, #MPU_RAM_REGION
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isb
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/* Full access from PL0, PL1, shared for CONFIG_SMP, cacheable */
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ldr r0, =PHYS_OFFSET @ RAM starts at PHYS_OFFSET
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ldr r5,=(MPU_AP_PL1RW_PL0RW | MPU_RGN_NORMAL)
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setup_region r0, r5, r6, MPU_DATA_SIDE @ PHYS_OFFSET, shared, enabled
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beq 1f @ Memory-map not unified
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setup_region r0, r5, r6, MPU_INSTR_SIDE @ PHYS_OFFSET, shared, enabled
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1: isb
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/* First/background region */
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set_region_nr r0, #MPU_BG_REGION
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isb
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/* Execute Never, strongly ordered, inaccessible to PL0, rw PL1 */
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mov r0, #0 @ BG region starts at 0x0
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ldr r5,=(MPU_ACR_XN | MPU_RGN_STRONGLY_ORDERED | MPU_AP_PL1RW_PL0NA)
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mov r6, #MPU_RSR_ALL_MEM @ 4GB region, enabled
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setup_region r0, r5, r6, MPU_DATA_SIDE @ 0x0, BG region, enabled
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beq 2f @ Memory-map not unified
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setup_region r0, r5, r6, MPU_INSTR_SIDE @ 0x0, BG region, enabled
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2: isb
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/* Enable the MPU */
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mrc p15, 0, r0, c1, c0, 0 @ Read SCTLR
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bic r0, r0, #CR_BR @ Disable the 'default mem-map'
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orr r0, r0, #CR_M @ Set SCTRL.M (MPU on)
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mcr p15, 0, r0, c1, c0, 0 @ Enable MPU
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isb
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mov pc,lr
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ENDPROC(__setup_mpu)
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#endif
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#include "head-common.S"
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