path: root/arch/powerpc/kernel/entry_64.S

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 *  PowerPC version 
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *  Rewritten by Cort Dougan (cort@cs.nmt.edu) for PReP
 *    Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
 *  Adapted for Power Macintosh by Paul Mackerras.
 *  Low-level exception handlers and MMU support
 *  rewritten by Paul Mackerras.
 *    Copyright (C) 1996 Paul Mackerras.
 *  MPC8xx modifications Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
 *
 *  This file contains the system call entry code, context switch
 *  code, and exception/interrupt return code for PowerPC.
 */

#include <linux/errno.h>
#include <linux/err.h>
#include <asm/cache.h>
#include <asm/unistd.h>
#include <asm/processor.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/thread_info.h>
#include <asm/code-patching-asm.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
#include <asm/cputable.h>
#include <asm/firmware.h>
#include <asm/bug.h>
#include <asm/ptrace.h>
#include <asm/irqflags.h>
#include <asm/hw_irq.h>
#include <asm/context_tracking.h>
#include <asm/tm.h>
#include <asm/ppc-opcode.h>
#include <asm/barrier.h>
#include <asm/export.h>
#include <asm/asm-compat.h>
#ifdef CONFIG_PPC_BOOK3S
#include <asm/exception-64s.h>
#else
#include <asm/exception-64e.h>
#endif
#include <asm/feature-fixups.h>
#include <asm/kup.h>

/*
 * System calls.
 */
	.section	".toc","aw"
SYS_CALL_TABLE:
	.tc sys_call_table[TC],sys_call_table

#ifdef CONFIG_COMPAT
COMPAT_SYS_CALL_TABLE:
	.tc compat_sys_call_table[TC],compat_sys_call_table
#endif

/* This value is used to mark exception frames on the stack. */
exception_marker:
	.tc	ID_EXC_MARKER[TC],STACK_FRAME_REGS_MARKER

	.section	".text"
	.align 7

	.globl system_call_common
system_call_common:
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
BEGIN_FTR_SECTION
	extrdi.	r10, r12, 1, (63-MSR_TS_T_LG) /* transaction active? */
	bne	.Ltabort_syscall
END_FTR_SECTION_IFSET(CPU_FTR_TM)
#endif
_ASM_NOKPROBE_SYMBOL(system_call_common)
	mr	r10,r1
	ld	r1,PACAKSAVE(r13)
	std	r10,0(r1)
	std	r11,_NIP(r1)
	std	r12,_MSR(r1)
	std	r0,GPR0(r1)
	std	r10,GPR1(r1)
	std	r2,GPR2(r1)
#ifdef CONFIG_PPC_FSL_BOOK3E
START_BTB_FLUSH_SECTION
	BTB_FLUSH(r10)
END_BTB_FLUSH_SECTION
#endif
	ld	r2,PACATOC(r13)
	mfcr	r12
	li	r11,0
	/* Can we avoid saving r3-r8 in common case? */
	std	r3,GPR3(r1)
	std	r4,GPR4(r1)
	std	r5,GPR5(r1)
	std	r6,GPR6(r1)
	std	r7,GPR7(r1)
	std	r8,GPR8(r1)
	/* Zero r9-r12, this should only be required when restoring all GPRs */
	std	r11,GPR9(r1)
	std	r11,GPR10(r1)
	std	r11,GPR11(r1)
	std	r11,GPR12(r1)
	std	r9,GPR13(r1)
	SAVE_NVGPRS(r1)
	std	r11,_XER(r1)
	std	r11,_CTR(r1)
	mflr	r10

	/*
	 * This clears CR0.SO (bit 28), which is the error indication on
	 * return from this system call.
	 */
	rldimi	r12,r11,28,(63-28)
	li	r11,0xc00
	std	r10,_LINK(r1)
	std	r11,_TRAP(r1)
	std	r12,_CCR(r1)
	std	r3,ORIG_GPR3(r1)
	addi	r10,r1,STACK_FRAME_OVERHEAD
	ld	r11,exception_marker@toc(r2)
	std	r11,-16(r10)		/* "regshere" marker */

	/*
	 * RECONCILE_IRQ_STATE without calling trace_hardirqs_off(), which
	 * would clobber syscall parameters. Also we always enter with IRQs
	 * enabled and nothing pending. system_call_exception() will call
	 * trace_hardirqs_off().
	 */
	li	r11,IRQS_ALL_DISABLED
	li	r12,PACA_IRQ_HARD_DIS
	stb	r11,PACAIRQSOFTMASK(r13)
	stb	r12,PACAIRQHAPPENED(r13)

	/* Calling convention has r9 = orig r0, r10 = regs */
	mr	r9,r0
	bl	system_call_exception

.Lsyscall_exit:
	addi    r4,r1,STACK_FRAME_OVERHEAD
	bl	syscall_exit_prepare

	ld	r2,_CCR(r1)
	ld	r4,_NIP(r1)
	ld	r5,_MSR(r1)
	ld	r6,_LINK(r1)

BEGIN_FTR_SECTION
	stdcx.	r0,0,r1			/* to clear the reservation */
END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)

	mtspr	SPRN_SRR0,r4
	mtspr	SPRN_SRR1,r5
	mtlr	r6

	cmpdi	r3,0
	bne	.Lsyscall_restore_regs
	/* Zero volatile regs that may contain sensitive kernel data */
	li	r0,0
	li	r4,0
	li	r5,0
	li	r6,0
	li	r7,0
	li	r8,0
	li	r9,0
	li	r10,0
	li	r11,0
	li	r12,0
	mtctr	r0
	mtspr	SPRN_XER,r0
.Lsyscall_restore_regs_cont:

BEGIN_FTR_SECTION
	HMT_MEDIUM_LOW
END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)

	/*
	 * We don't need to restore AMR on the way back to userspace for KUAP.
	 * The value of AMR only matters while we're in the kernel.
	 */
	mtcr	r2
	ld	r2,GPR2(r1)
	ld	r3,GPR3(r1)
	ld	r13,GPR13(r1)
	ld	r1,GPR1(r1)
	RFI_TO_USER
	b	.	/* prevent speculative execution */

.Lsyscall_restore_regs:
	ld	r3,_CTR(r1)
	ld	r4,_XER(r1)
	REST_NVGPRS(r1)
	mtctr	r3
	mtspr	SPRN_XER,r4
	ld	r0,GPR0(r1)
	REST_8GPRS(4, r1)
	ld	r12,GPR12(r1)
	b	.Lsyscall_restore_regs_cont

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
.Ltabort_syscall:
	/* Firstly we need to enable TM in the kernel */
	mfmsr	r10
	li	r9, 1
	rldimi	r10, r9, MSR_TM_LG, 63-MSR_TM_LG
	mtmsrd	r10, 0

	/* tabort, this dooms the transaction, nothing else */
	li	r9, (TM_CAUSE_SYSCALL|TM_CAUSE_PERSISTENT)
	TABORT(R9)

	/*
	 * Return directly to userspace. We have corrupted user register state,
	 * but userspace will never see that register state. Execution will
	 * resume after the tbegin of the aborted transaction with the
	 * checkpointed register state.
	 */
	li	r9, MSR_RI
	andc	r10, r10, r9
	mtmsrd	r10, 1
	mtspr	SPRN_SRR0, r11
	mtspr	SPRN_SRR1, r12
	RFI_TO_USER
	b	.	/* prevent speculative execution */
#endif

_GLOBAL(ret_from_fork)
	bl	schedule_tail
	REST_NVGPRS(r1)
	li	r3,0
	b	.Lsyscall_exit

_GLOBAL(ret_from_kernel_thread)
	bl	schedule_tail
	REST_NVGPRS(r1)
	mtlr	r14
	mr	r3,r15
#ifdef PPC64_ELF_ABI_v2
	mr	r12,r14
#endif
	blrl
	li	r3,0
	b	.Lsyscall_exit

#ifdef CONFIG_PPC_BOOK3E
/* Save non-volatile GPRs, if not already saved. */
_GLOBAL(save_nvgprs)
	ld	r11,_TRAP(r1)
	andi.	r0,r11