/* SPDX-License-Identifier: GPL-2.0 */#include <linux/init.h>#include <linux/linkage.h> #include <asm/assembler.h>#include <asm/asm-offsets.h>#include <asm/errno.h>#include <asm/thread_info.h>#include <asm/uaccess-asm.h>#include <asm/v7m.h> @ Bad Abort numbers@ -----------------@#define BAD_PREFETCH	0#define BAD_DATA	1#define BAD_ADDREXCPTN	2#define BAD_IRQ		3#define BAD_UNDEFINSTR	4 @@ Most of the stack format comes from struct pt_regs, but with@ the addition of 8 bytes for storing syscall args 5 and 6.@ This _must_ remain a multiple of 8 for EABI.@#define S_OFF		8 /*  * The SWI code relies on the fact that R0 is at the bottom of the stack * (due to slow/fast restore user regs). */#if S_R0 != 0#error "Please fix"#endif 	.macro	zero_fp#ifdef CONFIG_FRAME_POINTER	mov	fp, #0#endif	.endm #ifdef CONFIG_ALIGNMENT_TRAP#define ATRAP(x...) x#else#define ATRAP(x...)#endif 	.macro	alignment_trap, rtmp1, rtmp2, label#ifdef CONFIG_ALIGNMENT_TRAP	mrc	p15, 0, \rtmp2, c1, c0, 0	ldr_va	\rtmp1, \label	teq	\rtmp1, \rtmp2	mcrne	p15, 0, \rtmp1, c1, c0, 0#endif	.endm #ifdef CONFIG_CPU_V7M/* * ARMv7-M exception entry/exit macros. * * xPSR, ReturnAddress(), LR (R14), R12, R3, R2, R1, and R0 are * automatically saved on the current stack (32 words) before * switching to the exception stack (SP_main). * * If exception is taken while in user mode, SP_main is * empty. Otherwise, SP_main is aligned to 64 bit automatically * (CCR.STKALIGN set). * * Linux assumes that the interrupts are disabled when entering an * exception handler and it may BUG if this is not the case. Interrupts * are disabled during entry and reenabled in the exit macro. * * v7m_exception_slow_exit is used when returning from SVC or PendSV. * When returning to kernel mode, we don't return from exception. */	.macro	v7m_exception_entry	@ determine the location of the registers saved by the core during	@ exception entry. Depending on the mode the cpu was in when the	@ exception happend that is either on the main or the process stack.	@ Bit 2 of EXC_RETURN stored in the lr register specifies which stack	@ was used.	tst	lr, #EXC_RET_STACK_MASK	mrsne	r12, psp	moveq	r12, sp 	@ we cannot rely on r0-r3 and r12 matching the value saved in the	@ exception frame because of tail-chaining. So these have to be	@ reloaded.	ldmia	r12!, {r0-r3} 	@ Linux expects to have irqs off. Do it here before taking stack space	cpsid	i 	sub	sp, #PT_REGS_SIZE-S_IP	stmdb	sp!, {r0-r11} 	@ load saved r12, lr, return address and xPSR.	@ r0-r7 are used for signals and never touched from now on. Clobbering	@ r8-r12 is OK.	mov	r9, r12	ldmia	r9!, {r8, r10-r12} 	@ calculate the original stack pointer value.	@ r9 currently points to the memory location just above the auto saved	@ xPSR.	@ The cpu might automatically 8-byte align the stack. Bit 9	@ of the saved xPSR specifies if stack aligning took place. In this case	@ another 32-bit value is included in the stack. 	tst	r12, V7M_xPSR_FRAMEPTRALIGN	addne	r9, r9, #4 	@ store saved r12 using str to have a register to hold the base for stm	str	r8, [sp, #S_IP]	add	r8, sp, #S_SP	@ store r13-r15, xPSR	stmia	r8!, {r9-r12}	@ store old_r0	str	r0, [r8]	.endm         /*	 * PENDSV and SVCALL are configured to have the same exception	 * priorities. As a kernel thread runs at SVCALL execution priority it	 * can never be preempted and so we will never have to return to a	 * kernel thread here.         */	.macro	v7m_exception_slow_exit ret_r0	cpsid	i	ldr	lr, =exc_ret	ldr	lr, [lr] 	@ read original r12, sp, lr, pc and xPSR	add	r12, sp, #S_IP	ldmia	r12, {r1-r5} 	@ an exception frame is always 8-byte aligned. To tell the hardware if	@ the sp to be restored is aligned or not set bit 9 of the saved xPSR	@ accordingly.	tst	r2, #4	subne	r2, r2, #4	orrne	r5, V7M_xPSR_FRAMEPTRALIGN	biceq	r5, V7M_xPSR_FRAMEPTRALIGN 	@ ensure bit 0 is cleared in the PC, otherwise behaviour is	@ unpredictable	bic	r4, #1 	@ write basic exception frame	stmdb	r2!, {r1, r3-r5}	ldmia	sp, {r1, r3-r5}	.if	\ret_r0	stmdb	r2!, {r0, r3-r5}	.else	stmdb	r2!, {r1, r3-r5}	.endif 	@ restore process sp	msr	psp, r2 	@ restore original r4-r11	ldmia	sp!, {r0-r11} 	@ restore main sp	add	sp, sp, #PT_REGS_SIZE-S_IP 	cpsie	i	bx	lr	.endm#endif	/* CONFIG_CPU_V7M */ 	@	@ Store/load the USER SP and LR registers by switching to the SYS	@ mode. Useful in Thumb-2 mode where "stm/ldm rd, {sp, lr}^" is not	@ available. Should only be called from SVC mode	@	.macro	store_user_sp_lr, rd, rtemp, offset = 0	mrs	\rtemp, cpsr	eor	\rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)	msr	cpsr_c, \rtemp			@ switch to the SYS mode 	str	sp, [\rd, #\offset]		@ save sp_usr	str	lr, [\rd, #\offset + 4]		@ save lr_usr 	eor	\rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)	msr	cpsr_c, \rtemp			@ switch back to the SVC mode	.endm 	.macro	load_user_sp_lr, rd, rtemp, offset = 0	mrs	\rtemp, cpsr	eor	\rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)	msr	cpsr_c, \rtemp			@ switch to the SYS mode 	ldr	sp, [\rd, #\offset]		@ load sp_usr	ldr	lr, [\rd, #\offset + 4]		@ load lr_usr 	eor	\rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)	msr	cpsr_c, \rtemp			@ switch back to the SVC mode	.endm  	.macro	svc_exit, rpsr, irq = 0	.if	\irq != 0	@ IRQs already off#ifdef CONFIG_TRACE_IRQFLAGS	@ The parent context IRQs must have been enabled to get here in	@ the first place, so there's no point checking the PSR I bit.	bl	trace_hardirqs_on#endif	.else	@ IRQs off again before pulling preserved data off the stack	disable_irq_notrace#ifdef CONFIG_TRACE_IRQFLAGS	tst	\rpsr, #PSR_I_BIT	bleq	trace_hardirqs_on	tst	\rpsr, #PSR_I_BIT	blne	trace_hardirqs_off#endif	.endif	uaccess_exit tsk, r0, r1 #ifndef CONFIG_THUMB2_KERNEL	@ ARM mode SVC restore	msr	spsr_cxsf, \rpsr#if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_32v6K)	@ We must avoid clrex due to Cortex-A15 erratum #830321	sub	r0, sp, #4			@ uninhabited address	strex	r1, r2, [r0]			@ clear the exclusive monitor#endif	ldmia	sp, {r0 - pc}^			@ load r0 - pc, cpsr#else	@ Thumb mode SVC restore	ldr	lr, [sp, #S_SP]			@ top of the stack	ldrd	r0, r1, [sp, #S_LR]		@ calling lr and pc 	@ We must avoid clrex due to Cortex-A15 erratum #830321	strex	r2, r1, [sp, #S_LR]		@ clear the exclusive monitor 	stmdb	lr!, {r0, r1, \rpsr}		@ calling lr and rfe context	ldmia	sp, {r0 - r12}	mov	sp, lr	ldr	lr, [sp], #4	rfeia	sp!#endif	.endm 	@	@ svc_exit_via_fiq - like svc_exit but switches to FIQ mode before exit	@	@ This macro acts in a similar manner to svc_exit but switches to FIQ	@ mode to restore the final part of the register state.	@	@ We cannot use the normal svc_exit procedure because that would	@ clobber spsr_svc (FIQ could be delivered during the first few	@ instructions of vector_swi meaning its contents have not been	@ saved anywhere).	@	@ Note that, unlike svc_exit, this macro also does not allow a caller	@ supplied rpsr. This is because the FIQ exceptions are not re-entrant	@ and the handlers cannot call into the scheduler (meaning the value	@ on the stack remains correct).	@	.macro  svc_exit_via_fiq	uaccess_exit tsk, r0, r1#ifndef CONFIG_THUMB2_KERNEL	@ ARM mode restore	mov	r0, sp	ldmib	r0, {r1 - r14}	@ abort is deadly from here onward (it will				@ clobber state restored below)	msr	cpsr_c, #FIQ_MODE | PSR_I_BIT | PSR_F_BIT	add	r8, r0, #S_PC	ldr	r9, [r0, #S_PSR]	msr	spsr_cxsf, r9	ldr	r0, [r0, #S_R0]	ldmia	r8, {pc}^#else	@ Thumb mode restore	add	r0, sp, #S_R2	ldr	lr, [sp, #S_LR]	ldr	sp, [sp, #S_SP] @ abort is deadly from here onward (it will			        @ clobber state restored below)	ldmia	r0, {r2 - r12}	mov	r1, #FIQ_MODE | PSR_I_BIT | PSR_F_BIT	msr	cpsr_c, r1	sub	r0, #S_R2	add	r8, r0, #S_PC	ldmia	r0, {r0 - r1}	rfeia	r8#endif	.endm  	.macro	restore_user_regs, fast = 0, offset = 0#if defined(CONFIG_CPU_32v6K) && \    (!defined(CONFIG_CPU_V6) || defined(CONFIG_SMP))#ifdef CONFIG_CPU_V6ALT_SMP(nop)ALT_UP_B(.L1_\@)#endif	@ The TLS register update is deferred until return to user space so we	@ can use it for other things while running in the kernel	mrc	p15, 0, r1, c13, c0, 3		@ get current_thread_info pointer	ldr	r1, [r1, #TI_TP_VALUE]	mcr	p15, 0, r1, c13, c0, 3		@ set TLS register.L1_\@:#endif 	uaccess_enable r1, isb=0#ifndef CONFIG_THUMB2_KERNEL	@ ARM mode restore	mov	r2, sp	ldr	r1, [r2, #\offset + S_PSR]	@ get calling cpsr	ldr	lr, [r2, #\offset + S_PC]!	@ get pc	tst	r1, #PSR_I_BIT | 0x0f	bne	1f	msr	spsr_cxsf, r1			@ save in spsr_svc#if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_32v6K)	@ We must avoid clrex due to Cortex-A15 erratum #830321	strex	r1, r2, [r2]			@ clear the exclusive monitor#endif	.if	\fast	ldmdb	r2, {r1 - lr}^			@ get calling r1 - lr	.else	ldmdb	r2, {r0 - lr}^			@ get calling r0 - lr	.endif	mov	r0, r0				@ ARMv5T and earlier require a nop						@ after ldm {}^	add	sp, sp, #\offset + PT_REGS_SIZE	movs	pc, lr				@ return & move spsr_svc into cpsr1:	bug	"Returning to usermode but unexpected PSR bits set?", \@#elif defined(CONFIG_CPU_V7M)	@ V7M restore.	@ Note that we don't need to do clrex here as clearing the local	@ monitor is part of the exception entry and exit sequence.	.if	\offset	add	sp, #\offset	.endif	v7m_exception_slow_exit ret_r0 = \fast#else	@ Thumb mode restore	mov	r2, sp	load_user_sp_lr r2, r3, \offset + S_SP	@ calling sp, lr	ldr	r1, [sp, #\offset + S_PSR]	@ get calling cpsr	ldr	lr, [sp, #\offset + S_PC]	@ get pc	add	sp, sp, #\offset + S_SP	tst	r1, #PSR_I_BIT | 0x0f	bne	1f	msr	spsr_cxsf, r1			@ save in spsr_svc 	@ We must avoid clrex due to Cortex-A15 erratum #830321	strex	r1, r2, [sp]			@ clear the exclusive monitor 	.if	\fast	ldmdb	sp, {r1 - r12}			@ get calling r1 - r12	.else	ldmdb	sp, {r0 - r12}			@ get calling r0 - r12	.endif	add	sp, sp, #PT_REGS_SIZE - S_SP	movs	pc, lr				@ return & move spsr_svc into cpsr1:	bug	"Returning to usermode but unexpected PSR bits set?", \@#endif	/* !CONFIG_THUMB2_KERNEL */	.endm /* * Context tracking subsystem.  Used to instrument transitions * between user and kernel mode. */	.macro ct_user_exit, save = 1#ifdef CONFIG_CONTEXT_TRACKING_USER	.if	\save	stmdb   sp!, {r0-r3, ip, lr}	bl	user_exit_callable	ldmia	sp!, {r0-r3, ip, lr}	.else	bl	user_exit_callable	.endif#endif	.endm 	.macro ct_user_enter, save = 1#ifdef CONFIG_CONTEXT_TRACKING_USER	.if	\save	stmdb   sp!, {r0-r3, ip, lr}	bl	user_enter_callable	ldmia	sp!, {r0-r3, ip, lr}	.else	bl	user_enter_callable	.endif#endif	.endm 	.macro	invoke_syscall, table, nr, tmp, ret, reload=0#ifdef CONFIG_CPU_SPECTRE	mov	\tmp, \nr	cmp	\tmp, #NR_syscalls		@ check upper syscall limit	movcs	\tmp, #0	csdb	badr	lr, \ret			@ return address	.if	\reload	add	r1, sp, #S_R0 + S_OFF		@ pointer to regs	ldmiacc	r1, {r0 - r6}			@ reload r0-r6	stmiacc	sp, {r4, r5}			@ update stack arguments	.endif	ldrcc	pc, [\table, \tmp, lsl #2]	@ call sys_* routine#else	cmp	\nr, #NR_syscalls		@ check upper syscall limit	badr	lr, \ret			@ return address	.if	\reload	add	r1, sp, #S_R0 + S_OFF		@ pointer to regs	ldmiacc	r1, {r0 - r6}			@ reload r0-r6	stmiacc	sp, {r4, r5}			@ update stack arguments	.endif	ldrcc	pc, [\table, \nr, lsl #2]	@ call sys_* routine#endif	.endm /* * These are the registers used in the syscall handler, and allow us to * have in theory up to 7 arguments to a function - r0 to r6. * * r7 is reserved for the system call number for thumb mode. * * Note that tbl == why is intentional. * * We must set at least "tsk" and "why" when calling ret_with_reschedule. */scno	.req	r7		@ syscall numbertbl	.req	r8		@ syscall table pointerwhy	.req	r8		@ Linux syscall (!= 0)tsk	.req	r9		@ current thread_info 	.macro	do_overflow_check, frame_size:req#ifdef CONFIG_VMAP_STACK	@	@ Test whether the SP has overflowed. Task and IRQ stacks are aligned	@ so that SP & BIT(THREAD_SIZE_ORDER + PAGE_SHIFT) should always be	@ zero.	@ARM(	tst	sp, #1 << (THREAD_SIZE_ORDER + PAGE_SHIFT)	)THUMB(	tst	r1, #1 << (THREAD_SIZE_ORDER + PAGE_SHIFT)	)THUMB(	it	ne						)	bne	.Lstack_overflow_check\@ 	.pushsection	.text.Lstack_overflow_check\@:	@	@ The stack pointer is not pointing to a valid vmap'ed stack, but it	@ may be pointing into the linear map instead, which may happen if we	@ are already running from the overflow stack. We cannot detect overflow	@ in such cases so just carry on.	@	str	ip, [r0, #12]			@ Stash IP on the mode stack	ldr_va	ip, high_memory			@ Start of VMALLOC spaceARM(	cmp	sp, ip			)	@ SP in vmalloc space?THUMB(	cmp	r1, ip			)THUMB(	itt	lo			)	ldrlo	ip, [r0, #12]			@ Restore IP	blo	.Lout\@				@ Carry on THUMB(	sub	r1, sp, r1		)	@ Restore original R1THUMB(	sub	sp, r1			)	@ Restore original SP	add	sp, sp, #\frame_size		@ Undo svc_entry's SP change	b	__bad_stack			@ Handle VMAP stack overflow	.popsection.Lout\@:#endif	.endm