path: root/arch/arm/kernel/head-nommu.S

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 *  linux/arch/arm/kernel/head-nommu.S
 *
 *  Copyright (C) 1994-2002 Russell King
 *  Copyright (C) 2003-2006 Hyok S. Choi
 *
 *  Common kernel startup code (non-paged MM)
 */
#include <linux/linkage.h>
#include <linux/init.h>
#include <linux/errno.h>

#include <asm/assembler.h>
#include <asm/ptrace.h>
#include <asm/asm-offsets.h>
#include <asm/memory.h>
#include <asm/cp15.h>
#include <asm/thread_info.h>
#include <asm/v7m.h>
#include <asm/mpu.h>
#include <asm/page.h>

/*
 * Kernel startup entry point.
 * ---------------------------
 *
 * This is normally called from the decompressor code.  The requirements
 * are: MMU = off, D-cache = off, I-cache = dont care, r0 = 0,
 * r1 = machine nr.
 *
 * See linux/arch/arm/tools/mach-types for the complete list of machine
 * numbers for r1.
 *
 */

	__HEAD

#ifdef CONFIG_CPU_THUMBONLY
	.thumb
ENTRY(stext)
#else
	.arm
ENTRY(stext)

 THUMB(	badr	r9, 1f		)	@ Kernel is always entered in ARM.
 THUMB(	bx	r9		)	@ If this is a Thumb-2 kernel,
 THUMB(	.thumb			)	@ switch to Thumb now.
 THUMB(1:			)
#endif

#ifdef CONFIG_ARM_VIRT_EXT
	bl	__hyp_stub_install
#endif
	@ ensure svc mode and all interrupts masked
	safe_svcmode_maskall r9
						@ and irqs disabled
#if defined(CONFIG_CPU_CP15)
	mrc	p15, 0, r9, c0, c0		@ get processor id
#elif defined(CONFIG_CPU_V7M)
	ldr	r9, =BASEADDR_V7M_SCB
	ldr	r9, [r9, V7M_SCB_CPUID]
#else
	ldr	r9, =CONFIG_PROCESSOR_ID
#endif
	bl	__lookup_processor_type		@ r5=procinfo r9=cpuid
	movs	r10, r5				@ invalid processor (r5=0)?
	beq	__error_p				@ yes, error 'p'

#ifdef CONFIG_ARM_MPU
	bl	__setup_mpu
#endif

	badr	lr, 1f				@ return (PIC) address
	ldr	r12, [r10, #PROCINFO_INITFUNC]
	add	r12, r12, r10
	ret	r12
1:	ldr	lr, =__mmap_switched
	b	__after_proc_init
ENDPROC(stext)

#ifdef CONFIG_SMP
	.text
ENTRY(secondary_startup)
	/*
	 * Common entry point for secondary CPUs.
	 *
	 * Ensure that we're in SVC mode, and IRQs are disabled.  Lookup
	 * the processor type - there is no need to check the machine type
	 * as it has already been validated by the primary processor.
	 */
#ifdef CONFIG_ARM_VIRT_EXT
	bl	__hyp_stub_install_secondary
#endif
	safe_svcmode_maskall r9

#ifndef CONFIG_CPU_CP15
	ldr	r9, =CONFIG_PROCESSOR_ID
#else
	mrc	p15, 0, r9, c0, c0		@ get processor id
#endif
	bl	__lookup_processor_type		@ r5=procinfo r9=cpuid
	movs	r10, r5				@ invalid processor?
	beq	__error_p			@ yes, error 'p'

	ldr	r7, __secondary_data

#ifdef CONFIG_ARM_MPU
	bl      __secondary_setup_mpu		@ Initialize the MPU
#endif

	badr	lr, 1f				@ return (PIC) address
	ldr	r12, [r10, #PROCINFO_INITFUNC]
	add	r12, r12, r10
	ret	r12
1:	bl	__after_proc_init
	ldr	sp, [r7, #12]			@ set up the stack pointer
	mov	fp, #0
	b	secondary_start_kernel
ENDPROC(secondary_startup)

	.type	__secondary_data, %object
__secondary_data:
	.long	secondary_data
#endif /* CONFIG_SMP */

/*
 * Set the Control Register and Read the process ID.
 */
	.text
__after_proc_init:
M_CLASS(movw	r12, #:lower16:BASEADDR_V7M_SCB)
M_CLASS(movt	r12, #:upper16:BASEADDR_V7M_SCB)
#ifdef CONFIG_ARM_MPU
M_CLASS(ldr	r3, [r12, 0x50])
AR_CLASS(mrc	p15, 0, r3, c0, c1, 4)          @ Read ID_MMFR0
	and	r3, r3, #(MMFR0_PMSA)           @ PMSA field
	teq	r3, #(MMFR0_PMSAv7)             @ PMSA v7
	beq	1f
	teq	r3, #(MMFR0_PMSAv8)		@ PMSA v8
	/*
	 * Memory region attributes for PMSAv8:
	 *
	 *   n = AttrIndx[2:0]
	 *                      n       MAIR
	 *   DEVICE_nGnRnE      000     00000000
	 *   NORMAL             001     11111111
	 */
	ldreq	r3, =PMSAv8_MAIR(0x00, PMSAv8_RGN_DEVICE_nGnRnE) | \
		     PMSAv8_MAIR(0xff, PMSAv8_RGN_NORMAL)
AR_CLASS(mcreq	p15, 0, r3, c10, c2, 0)		@ MAIR 0
M_CLASS(streq	r3, [r12, #PMSAv8_MAIR0])
	moveq	r3, #0
AR_CLASS(mcreq	p15, 0, r3, c10, c2, 1)		@ MAIR 1
M_CLASS(streq	r3, [r12, #PMSAv8_MAIR1])

1:
#endif
#ifdef CONFIG_CPU_CP15
	/*
	 * CP15 system control register value returned in r0 from
	 * the CPU init function.
	 */

#ifdef CONFIG_ARM_MPU
	biceq	r0, r0, #CR_BR			@ Disable the 'default mem-map'
	orreq	r0, r0, #CR_M			@ Set SCTRL.M (MPU on)
#endif
#if defined(CONFIG_ALIGNMENT_TRAP) && __LINUX_ARM_ARCH__ < 6
	orr	r0, r0, #CR_A
#else
	bic	r0, r0, #CR_A
#endif
#ifdef CONFIG_CPU_DCACHE_DISABLE
	bic	r0, r0, #CR_C
#endif
#ifdef CONFIG_CPU_BPREDICT_DISABLE
	bic	r0, r0, #CR_Z
#endif
#ifdef CONFIG_CPU_ICACHE_DISABLE
	bic	r0, r0, #CR_I
#endif
	mcr	p15, 0, r0, c1, c0, 0		@ write control reg
	instr_sync
#elif defined (CONFIG_CPU_V7M)
#ifdef CONFIG_ARM_MPU
	ldreq	r3, [r12, MPU_CTRL]
	biceq	r3, #MPU_CTRL_PRIVDEFENA
	orreq	r3, #MPU_CTRL_ENABLE
	streq	r3, [r12, MPU_CTRL]
	isb
#endif
	/* For V7M systems we want to modify the CCR similarly to the SCTLR */
#ifdef CONFIG_CPU_DCACHE_DISABLE
	bic	r0, r0, #V7M_SCB_CCR_DC
#endif
#ifdef CONFIG_CPU_BPREDICT_DISABLE
	bic	r0, r0, #V7M_SCB_CCR_BP
#endif
#ifdef CONFIG_CPU_ICACHE_DISABLE
	bic	r0, r0, #V7M_SCB_CCR_IC
#endif
	str	r0, [r12, V7M_SCB_CCR]
#endif /* CONFIG_CPU_CP15 elif CONFIG_CPU_V7M */
	ret	lr
ENDPROC(__after_proc_init)
	.ltorg

#ifdef CONFIG_ARM_MPU


#ifndef CONFIG_CPU_V7M
/* Set which MPU region should be programmed */
.macro set_region_nr tmp, rgnr, unused
	mov	\tmp, \rgnr			@ Use static region numbers
	mcr	p15, 0, \tmp, c6, c2, 0		@ Write RGNR
.endm

/* Setup a single MPU region, either D or I side (D-side for unified) */
.macro setup_region bar, acr, sr, side = PMSAv7_DATA_SIDE, unused
	mcr	p15, 0, \bar, c6, c1, (0 + \side)	@ I/DRBAR
	mcr	p15, 0, \acr, c6, c1, (4 + \side)	@ I/DRACR
	mcr	p15, 0, \sr, c6, c1, (2 + \side)		@ I/DRSR
.endm
#else
.macro set_region_nr tmp, rgnr, base
	mov	\tmp, \rgnr
	str     \tmp, [\base, #PMSAv7_RNR]
.endm

.macro setup_region bar, acr, sr, unused, base
	lsl     \acr, \acr, #16
	orr     \acr, \acr, \sr
	str     \bar, [\base, #PMSAv7_RBAR]
	str     \acr, [\base, #PMSAv7_RASR]
.endm

#endif
/*
 * Setup the MPU and initial MPU Regions. We create the following regions:
 * Region 0: Use this for probing the MPU details, so leave disabled.
 * Region 1: Background region - covers the whole of RAM as strongly ordered
 * Region 2: Normal, Shared, cacheable for RAM. From PHYS_OFFSET, size from r6
 * Region 3: Normal, shared, inaccessible from PL0 to protect the vectors page
 *
 * r6: Value to be written to DRSR (and IRSR if required) for PMSAv7_RAM_REGION
*/
	__HEAD

ENTRY(__setup_mpu)

	/* Probe for v7 PMSA compliance */
M_CLASS(movw	r12, #:lower16:BASEADDR_V7M_SCB)
M_CLASS(movt	r12, #:upper16:BASEADDR_V7M_SCB)

AR_CLASS(mrc	p15, 0, r0, c0, c1, 4)		@ Read ID_MMFR0
M_CLASS(ldr	r0, [r12, 0x50])
	and	r0, r0, #(MMFR0_PMSA)		@ PMSA field
	teq	r0,