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WSL2-Linux-Kernel
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WSL2-Linux-Kernel/arch/arm64/kernel/entry.S

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ArmAsm
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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Low-level exception handling code
*
* Copyright (C) 2012 ARM Ltd.
* Authors: Catalin Marinas <catalin.marinas@arm.com>
* Will Deacon <will.deacon@arm.com>
*/
#include <linux/arm-smccc.h>
#include <linux/init.h>
#include <linux/linkage.h>
#include <asm/alternative.h>
#include <asm/assembler.h>
#include <asm/asm-offsets.h>
#include <asm/asm_pointer_auth.h>
#include <asm/cpufeature.h>
#include <asm/errno.h>
#include <asm/esr.h>
#include <asm/irq.h>
#include <asm/memory.h>
#include <asm/mmu.h>
#include <asm/processor.h>
#include <asm/ptrace.h>
#include <asm/thread_info.h>
#include <asm/asm-uaccess.h>
#include <asm/unistd.h>
/*
* Context tracking subsystem. Used to instrument transitions
* between user and kernel mode.
*/
.macro ct_user_exit_irqoff
#ifdef CONFIG_CONTEXT_TRACKING
bl enter_from_user_mode
#endif
.endm
.macro ct_user_enter
#ifdef CONFIG_CONTEXT_TRACKING
bl context_tracking_user_enter
#endif
.endm
.macro clear_gp_regs
.irp n,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29
mov x\n, xzr
.endr
.endm
/*
* Bad Abort numbers
*-----------------
*/
#define BAD_SYNC 0
#define BAD_IRQ 1
#define BAD_FIQ 2
#define BAD_ERROR 3
.macro kernel_ventry, el, label, regsize = 64
.align 7
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
.if \el == 0
alternative_if ARM64_UNMAP_KERNEL_AT_EL0
.if \regsize == 64
mrs x30, tpidrro_el0
msr tpidrro_el0, xzr
.else
mov x30, xzr
.endif
alternative_else_nop_endif
.endif
#endif
sub sp, sp, #S_FRAME_SIZE
#ifdef CONFIG_VMAP_STACK
/*
* Test whether the SP has overflowed, without corrupting a GPR.
* Task and IRQ stacks are aligned so that SP & (1 << THREAD_SHIFT)
* should always be zero.
*/
add sp, sp, x0 // sp' = sp + x0
sub x0, sp, x0 // x0' = sp' - x0 = (sp + x0) - x0 = sp
tbnz x0, #THREAD_SHIFT, 0f
sub x0, sp, x0 // x0'' = sp' - x0' = (sp + x0) - sp = x0
sub sp, sp, x0 // sp'' = sp' - x0 = (sp + x0) - x0 = sp
b el\()\el\()_\label
0:
/*
* Either we've just detected an overflow, or we've taken an exception
* while on the overflow stack. Either way, we won't return to
* userspace, and can clobber EL0 registers to free up GPRs.
*/
/* Stash the original SP (minus S_FRAME_SIZE) in tpidr_el0. */
msr tpidr_el0, x0
/* Recover the original x0 value and stash it in tpidrro_el0 */
sub x0, sp, x0
msr tpidrro_el0, x0
/* Switch to the overflow stack */
adr_this_cpu sp, overflow_stack + OVERFLOW_STACK_SIZE, x0
/*
* Check whether we were already on the overflow stack. This may happen
* after panic() re-enables interrupts.
*/
mrs x0, tpidr_el0 // sp of interrupted context
sub x0, sp, x0 // delta with top of overflow stack
tst x0, #~(OVERFLOW_STACK_SIZE - 1) // within range?
b.ne __bad_stack // no? -> bad stack pointer
/* We were already on the overflow stack. Restore sp/x0 and carry on. */
sub sp, sp, x0
mrs x0, tpidrro_el0
#endif
b el\()\el\()_\label
.endm
.macro tramp_alias, dst, sym
mov_q \dst, TRAMP_VALIAS
add \dst, \dst, #(\sym - .entry.tramp.text)
.endm
// This macro corrupts x0-x3. It is the caller's duty
// to save/restore them if required.
.macro apply_ssbd, state, tmp1, tmp2
#ifdef CONFIG_ARM64_SSBD
alternative_cb arm64_enable_wa2_handling
b .L__asm_ssbd_skip\@
alternative_cb_end
ldr_this_cpu \tmp2, arm64_ssbd_callback_required, \tmp1
cbz \tmp2, .L__asm_ssbd_skip\@
ldr \tmp2, [tsk, #TSK_TI_FLAGS]
tbnz \tmp2, #TIF_SSBD, .L__asm_ssbd_skip\@
mov w0, #ARM_SMCCC_ARCH_WORKAROUND_2
mov w1, #\state
alternative_cb arm64_update_smccc_conduit
nop // Patched to SMC/HVC #0
alternative_cb_end
.L__asm_ssbd_skip\@:
#endif
.endm
.macro kernel_entry, el, regsize = 64
.if \regsize == 32
mov w0, w0 // zero upper 32 bits of x0
.endif
stp x0, x1, [sp, #16 * 0]
stp x2, x3, [sp, #16 * 1]
stp x4, x5, [sp, #16 * 2]
stp x6, x7, [sp, #16 * 3]
stp x8, x9, [sp, #16 * 4]
stp x10, x11, [sp, #16 * 5]
stp x12, x13, [sp, #16 * 6]
stp x14, x15, [sp, #16 * 7]
stp x16, x17, [sp, #16 * 8]
stp x18, x19, [sp, #16 * 9]
stp x20, x21, [sp, #16 * 10]
stp x22, x23, [sp, #16 * 11]
stp x24, x25, [sp, #16 * 12]
stp x26, x27, [sp, #16 * 13]
stp x28, x29, [sp, #16 * 14]
.if \el == 0
clear_gp_regs
mrs x21, sp_el0
ldr_this_cpu tsk, __entry_task, x20
msr sp_el0, tsk
// Ensure MDSCR_EL1.SS is clear, since we can unmask debug exceptions
// when scheduling.
ldr x19, [tsk, #TSK_TI_FLAGS]
disable_step_tsk x19, x20
apply_ssbd 1, x22, x23
ptrauth_keys_install_kernel tsk, 1, x20, x22, x23
.else
add x21, sp, #S_FRAME_SIZE
get_current_task tsk
/* Save the task's original addr_limit and set USER_DS */
ldr x20, [tsk, #TSK_TI_ADDR_LIMIT]
str x20, [sp, #S_ORIG_ADDR_LIMIT]
mov x20, #USER_DS
str x20, [tsk, #TSK_TI_ADDR_LIMIT]
/* No need to reset PSTATE.UAO, hardware's already set it to 0 for us */
.endif /* \el == 0 */
mrs x22, elr_el1
mrs x23, spsr_el1
stp lr, x21, [sp, #S_LR]
/*
* In order to be able to dump the contents of struct pt_regs at the
* time the exception was taken (in case we attempt to walk the call
* stack later), chain it together with the stack frames.
*/
.if \el == 0
stp xzr, xzr, [sp, #S_STACKFRAME]
.else
stp x29, x22, [sp, #S_STACKFRAME]
.endif
add x29, sp, #S_STACKFRAME
#ifdef CONFIG_ARM64_SW_TTBR0_PAN
/*
* Set the TTBR0 PAN bit in SPSR. When the exception is taken from
* EL0, there is no need to check the state of TTBR0_EL1 since
* accesses are always enabled.
* Note that the meaning of this bit differs from the ARMv8.1 PAN
* feature as all TTBR0_EL1 accesses are disabled, not just those to
* user mappings.
*/
alternative_if ARM64_HAS_PAN
b 1f // skip TTBR0 PAN
alternative_else_nop_endif
.if \el != 0
mrs x21, ttbr0_el1
tst x21, #TTBR_ASID_MASK // Check for the reserved ASID
orr x23, x23, #PSR_PAN_BIT // Set the emulated PAN in the saved SPSR
b.eq 1f // TTBR0 access already disabled
and x23, x23, #~PSR_PAN_BIT // Clear the emulated PAN in the saved SPSR
.endif
__uaccess_ttbr0_disable x21
1:
#endif
stp x22, x23, [sp, #S_PC]
/* Not in a syscall by default (el0_svc overwrites for real syscall) */
.if \el == 0
mov w21, #NO_SYSCALL
str w21, [sp, #S_SYSCALLNO]
.endif
/* Save pmr */
alternative_if ARM64_HAS_IRQ_PRIO_MASKING
mrs_s x20, SYS_ICC_PMR_EL1
str x20, [sp, #S_PMR_SAVE]
alternative_else_nop_endif
/*
* Registers that may be useful after this macro is invoked:
*
* x20 - ICC_PMR_EL1
* x21 - aborted SP
* x22 - aborted PC
* x23 - aborted PSTATE
*/
.endm
.macro kernel_exit, el
.if \el != 0
disable_daif
/* Restore the task's original addr_limit. */
ldr x20, [sp, #S_ORIG_ADDR_LIMIT]
str x20, [tsk, #TSK_TI_ADDR_LIMIT]
/* No need to restore UAO, it will be restored from SPSR_EL1 */
.endif
/* Restore pmr */
alternative_if ARM64_HAS_IRQ_PRIO_MASKING
ldr x20, [sp, #S_PMR_SAVE]
msr_s SYS_ICC_PMR_EL1, x20
mrs_s x21, SYS_ICC_CTLR_EL1
tbz x21, #6, .L__skip_pmr_sync\@ // Check for ICC_CTLR_EL1.PMHE
dsb sy // Ensure priority change is seen by redistributor
.L__skip_pmr_sync\@:
alternative_else_nop_endif
ldp x21, x22, [sp, #S_PC] // load ELR, SPSR
.if \el == 0
ct_user_enter
.endif
#ifdef CONFIG_ARM64_SW_TTBR0_PAN
/*
* Restore access to TTBR0_EL1. If returning to EL0, no need for SPSR
* PAN bit checking.
*/
alternative_if ARM64_HAS_PAN
b 2f // skip TTBR0 PAN
alternative_else_nop_endif
.if \el != 0
tbnz x22, #22, 1f // Skip re-enabling TTBR0 access if the PSR_PAN_BIT is set
.endif
__uaccess_ttbr0_enable x0, x1
.if \el == 0
/*
* Enable errata workarounds only if returning to user. The only
* workaround currently required for TTBR0_EL1 changes are for the
* Cavium erratum 27456 (broadcast TLBI instructions may cause I-cache
* corruption).
*/
bl post_ttbr_update_workaround
.endif
1:
.if \el != 0
and x22, x22, #~PSR_PAN_BIT // ARMv8.0 CPUs do not understand this bit
.endif
2:
#endif
.if \el == 0
ldr x23, [sp, #S_SP] // load return stack pointer
msr sp_el0, x23
tst x22, #PSR_MODE32_BIT // native task?
b.eq 3f
#ifdef CONFIG_ARM64_ERRATUM_845719
alternative_if ARM64_WORKAROUND_845719
#ifdef CONFIG_PID_IN_CONTEXTIDR
mrs x29, contextidr_el1
msr contextidr_el1, x29
#else
msr contextidr_el1, xzr
#endif
alternative_else_nop_endif
#endif
3:
#ifdef CONFIG_ARM64_ERRATUM_1418040
alternative_if_not ARM64_WORKAROUND_1418040
b 4f
alternative_else_nop_endif
/*
* if (x22.mode32 == cntkctl_el1.el0vcten)
* cntkctl_el1.el0vcten = ~cntkctl_el1.el0vcten
*/
mrs x1, cntkctl_el1
eon x0, x1, x22, lsr #3
tbz x0, #1, 4f
eor x1, x1, #2 // ARCH_TIMER_USR_VCT_ACCESS_EN
msr cntkctl_el1, x1
4:
#endif
/* No kernel C function calls after this as user keys are set. */
ptrauth_keys_install_user tsk, x0, x1, x2
apply_ssbd 0, x0, x1
.endif
msr elr_el1, x21 // set up the return data
msr spsr_el1, x22
ldp x0, x1, [sp, #16 * 0]
ldp x2, x3, [sp, #16 * 1]
ldp x4, x5, [sp, #16 * 2]
ldp x6, x7, [sp, #16 * 3]
ldp x8, x9, [sp, #16 * 4]
ldp x10, x11, [sp, #16 * 5]
ldp x12, x13, [sp, #16 * 6]
ldp x14, x15, [sp, #16 * 7]
ldp x16, x17, [sp, #16 * 8]
ldp x18, x19, [sp, #16 * 9]
ldp x20, x21, [sp, #16 * 10]
ldp x22, x23, [sp, #16 * 11]
ldp x24, x25, [sp, #16 * 12]
ldp x26, x27, [sp, #16 * 13]
ldp x28, x29, [sp, #16 * 14]
ldr lr, [sp, #S_LR]
add sp, sp, #S_FRAME_SIZE // restore sp
.if \el == 0
alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
bne 5f
msr far_el1, x30
tramp_alias x30, tramp_exit_native
br x30
5:
tramp_alias x30, tramp_exit_compat
br x30
#endif
.else
eret
.endif
sb
.endm
.macro irq_stack_entry
mov x19, sp // preserve the original sp
/*
* Compare sp with the base of the task stack.
* If the top ~(THREAD_SIZE - 1) bits match, we are on a task stack,
* and should switch to the irq stack.
*/
ldr x25, [tsk, TSK_STACK]
eor x25, x25, x19
and x25, x25, #~(THREAD_SIZE - 1)
cbnz x25, 9998f
ldr_this_cpu x25, irq_stack_ptr, x26
mov x26, #IRQ_STACK_SIZE
add x26, x25, x26
/* switch to the irq stack */
mov sp, x26
9998:
.endm
/*
* x19 should be preserved between irq_stack_entry and
* irq_stack_exit.
*/
.macro irq_stack_exit
mov sp, x19
.endm
/* GPRs used by entry code */
tsk .req x28 // current thread_info
/*
* Interrupt handling.
*/
.macro irq_handler
ldr_l x1, handle_arch_irq
mov x0, sp
irq_stack_entry
blr x1
irq_stack_exit
.endm
#ifdef CONFIG_ARM64_PSEUDO_NMI
/*
* Set res to 0 if irqs were unmasked in interrupted context.
* Otherwise set res to non-0 value.
*/
.macro test_irqs_unmasked res:req, pmr:req
alternative_if ARM64_HAS_IRQ_PRIO_MASKING
sub \res, \pmr, #GIC_PRIO_IRQON
alternative_else
mov \res, xzr
alternative_endif
.endm
#endif
.macro gic_prio_kentry_setup, tmp:req
#ifdef CONFIG_ARM64_PSEUDO_NMI
alternative_if ARM64_HAS_IRQ_PRIO_MASKING
mov \tmp, #(GIC_PRIO_PSR_I_SET | GIC_PRIO_IRQON)
msr_s SYS_ICC_PMR_EL1, \tmp
alternative_else_nop_endif
#endif
.endm
.macro gic_prio_irq_setup, pmr:req, tmp:req
#ifdef CONFIG_ARM64_PSEUDO_NMI
alternative_if ARM64_HAS_IRQ_PRIO_MASKING
orr \tmp, \pmr, #GIC_PRIO_PSR_I_SET
msr_s SYS_ICC_PMR_EL1, \tmp
alternative_else_nop_endif
#endif
.endm
.text
/*
* Exception vectors.
*/
.pushsection ".entry.text", "ax"
.align 11
SYM_CODE_START(vectors)
kernel_ventry 1, sync_invalid // Synchronous EL1t
kernel_ventry 1, irq_invalid // IRQ EL1t
kernel_ventry 1, fiq_invalid // FIQ EL1t
kernel_ventry 1, error_invalid // Error EL1t
kernel_ventry 1, sync // Synchronous EL1h
kernel_ventry 1, irq // IRQ EL1h
kernel_ventry 1, fiq_invalid // FIQ EL1h
kernel_ventry 1, error // Error EL1h
kernel_ventry 0, sync // Synchronous 64-bit EL0
kernel_ventry 0, irq // IRQ 64-bit EL0
kernel_ventry 0, fiq_invalid // FIQ 64-bit EL0
kernel_ventry 0, error // Error 64-bit EL0
#ifdef CONFIG_COMPAT
kernel_ventry 0, sync_compat, 32 // Synchronous 32-bit EL0
kernel_ventry 0, irq_compat, 32 // IRQ 32-bit EL0
kernel_ventry 0, fiq_invalid_compat, 32 // FIQ 32-bit EL0
kernel_ventry 0, error_compat, 32 // Error 32-bit EL0
#else
kernel_ventry 0, sync_invalid, 32 // Synchronous 32-bit EL0
kernel_ventry 0, irq_invalid, 32 // IRQ 32-bit EL0
kernel_ventry 0, fiq_invalid, 32 // FIQ 32-bit EL0
kernel_ventry 0, error_invalid, 32 // Error 32-bit EL0
#endif
SYM_CODE_END(vectors)
#ifdef CONFIG_VMAP_STACK
/*
* We detected an overflow in kernel_ventry, which switched to the
* overflow stack. Stash the exception regs, and head to our overflow
* handler.
*/
__bad_stack:
/* Restore the original x0 value */
mrs x0, tpidrro_el0
/*
* Store the original GPRs to the new stack. The orginal SP (minus
* S_FRAME_SIZE) was stashed in tpidr_el0 by kernel_ventry.
*/
sub sp, sp, #S_FRAME_SIZE
kernel_entry 1
mrs x0, tpidr_el0
add x0, x0, #S_FRAME_SIZE
str x0, [sp, #S_SP]
/* Stash the regs for handle_bad_stack */
mov x0, sp
/* Time to die */
bl handle_bad_stack
ASM_BUG()
#endif /* CONFIG_VMAP_STACK */
/*
* Invalid mode handlers
*/
.macro inv_entry, el, reason, regsize = 64
kernel_entry \el, \regsize
mov x0, sp
mov x1, #\reason
mrs x2, esr_el1
bl bad_mode
ASM_BUG()
.endm
SYM_CODE_START_LOCAL(el0_sync_invalid)
inv_entry 0, BAD_SYNC
SYM_CODE_END(el0_sync_invalid)
SYM_CODE_START_LOCAL(el0_irq_invalid)
inv_entry 0, BAD_IRQ
SYM_CODE_END(el0_irq_invalid)
SYM_CODE_START_LOCAL(el0_fiq_invalid)
inv_entry 0, BAD_FIQ
SYM_CODE_END(el0_fiq_invalid)
SYM_CODE_START_LOCAL(el0_error_invalid)
inv_entry 0, BAD_ERROR
SYM_CODE_END(el0_error_invalid)
#ifdef CONFIG_COMPAT
SYM_CODE_START_LOCAL(el0_fiq_invalid_compat)
inv_entry 0, BAD_FIQ, 32
SYM_CODE_END(el0_fiq_invalid_compat)
#endif
SYM_CODE_START_LOCAL(el1_sync_invalid)
inv_entry 1, BAD_SYNC
SYM_CODE_END(el1_sync_invalid)
SYM_CODE_START_LOCAL(el1_irq_invalid)
inv_entry 1, BAD_IRQ
SYM_CODE_END(el1_irq_invalid)
SYM_CODE_START_LOCAL(el1_fiq_invalid)
inv_entry 1, BAD_FIQ
SYM_CODE_END(el1_fiq_invalid)
SYM_CODE_START_LOCAL(el1_error_invalid)
inv_entry 1, BAD_ERROR
SYM_CODE_END(el1_error_invalid)
/*
* EL1 mode handlers.
*/
.align 6
SYM_CODE_START_LOCAL_NOALIGN(el1_sync)
kernel_entry 1
mov x0, sp
bl el1_sync_handler
kernel_exit 1
SYM_CODE_END(el1_sync)
.align 6
SYM_CODE_START_LOCAL_NOALIGN(el1_irq)
kernel_entry 1
gic_prio_irq_setup pmr=x20, tmp=x1
enable_da_f
#ifdef CONFIG_ARM64_PSEUDO_NMI
test_irqs_unmasked res=x0, pmr=x20
cbz x0, 1f
bl asm_nmi_enter
1:
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
bl trace_hardirqs_off
#endif
irq_handler
#ifdef CONFIG_PREEMPTION
ldr x24, [tsk, #TSK_TI_PREEMPT] // get preempt count
alternative_if ARM64_HAS_IRQ_PRIO_MASKING
/*
* DA_F were cleared at start of handling. If anything is set in DAIF,
* we come back from an NMI, so skip preemption
*/
mrs x0, daif
orr x24, x24, x0
alternative_else_nop_endif
cbnz x24, 1f // preempt count != 0 || NMI return path
bl arm64_preempt_schedule_irq // irq en/disable is done inside
1:
#endif
#ifdef CONFIG_ARM64_PSEUDO_NMI
/*
* When using IRQ priority masking, we can get spurious interrupts while
* PMR is set to GIC_PRIO_IRQOFF. An NMI might also have occurred in a
* section with interrupts disabled. Skip tracing in those cases.
*/
test_irqs_unmasked res=x0, pmr=x20
cbz x0, 1f
bl asm_nmi_exit
1:
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
#ifdef CONFIG_ARM64_PSEUDO_NMI
test_irqs_unmasked res=x0, pmr=x20
cbnz x0, 1f
#endif
bl trace_hardirqs_on
1:
#endif
kernel_exit 1
SYM_CODE_END(el1_irq)
/*
* EL0 mode handlers.
*/
.align 6
SYM_CODE_START_LOCAL_NOALIGN(el0_sync)
kernel_entry 0
mov x0, sp
bl el0_sync_handler
b ret_to_user
SYM_CODE_END(el0_sync)
#ifdef CONFIG_COMPAT
.align 6
SYM_CODE_START_LOCAL_NOALIGN(el0_sync_compat)
kernel_entry 0, 32
mov x0, sp
bl el0_sync_compat_handler
b ret_to_user
SYM_CODE_END(el0_sync_compat)
.align 6
SYM_CODE_START_LOCAL_NOALIGN(el0_irq_compat)
kernel_entry 0, 32
b el0_irq_naked
SYM_CODE_END(el0_irq_compat)
SYM_CODE_START_LOCAL_NOALIGN(el0_error_compat)
kernel_entry 0, 32
b el0_error_naked
SYM_CODE_END(el0_error_compat)
#endif
.align 6
SYM_CODE_START_LOCAL_NOALIGN(el0_irq)
kernel_entry 0
el0_irq_naked:
gic_prio_irq_setup pmr=x20, tmp=x0
ct_user_exit_irqoff
enable_da_f
#ifdef CONFIG_TRACE_IRQFLAGS
bl trace_hardirqs_off
#endif
#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
tbz x22, #55, 1f
bl do_el0_irq_bp_hardening
1:
#endif
irq_handler
#ifdef CONFIG_TRACE_IRQFLAGS
bl trace_hardirqs_on
#endif
b ret_to_user
SYM_CODE_END(el0_irq)
SYM_CODE_START_LOCAL(el1_error)
kernel_entry 1
mrs x1, esr_el1
gic_prio_kentry_setup tmp=x2
enable_dbg
mov x0, sp
bl do_serror
kernel_exit 1
SYM_CODE_END(el1_error)
SYM_CODE_START_LOCAL(el0_error)
kernel_entry 0
el0_error_naked:
mrs x25, esr_el1
gic_prio_kentry_setup tmp=x2
ct_user_exit_irqoff
enable_dbg
mov x0, sp
mov x1, x25
bl do_serror
enable_da_f
b ret_to_user
SYM_CODE_END(el0_error)
/*
* Ok, we need to do extra processing, enter the slow path.
*/
work_pending:
mov x0, sp // 'regs'
bl do_notify_resume
#ifdef CONFIG_TRACE_IRQFLAGS
bl trace_hardirqs_on // enabled while in userspace
#endif
ldr x1, [tsk, #TSK_TI_FLAGS] // re-check for single-step
b finish_ret_to_user
/*
* "slow" syscall return path.
*/
ret_to_user:
disable_daif
gic_prio_kentry_setup tmp=x3
ldr x1, [tsk, #TSK_TI_FLAGS]
and x2, x1, #_TIF_WORK_MASK
cbnz x2, work_pending
finish_ret_to_user:
enable_step_tsk x1, x2
#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
bl stackleak_erase
#endif
kernel_exit 0
ENDPROC(ret_to_user)
.popsection // .entry.text
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
/*
* Exception vectors trampoline.
*/
.pushsection ".entry.tramp.text", "ax"
.macro tramp_map_kernel, tmp
mrs \tmp, ttbr1_el1
add \tmp, \tmp, #(PAGE_SIZE + RESERVED_TTBR0_SIZE)
bic \tmp, \tmp, #USER_ASID_FLAG
msr ttbr1_el1, \tmp
#ifdef CONFIG_QCOM_FALKOR_ERRATUM_1003
alternative_if ARM64_WORKAROUND_QCOM_FALKOR_E1003
/* ASID already in \tmp[63:48] */
movk \tmp, #:abs_g2_nc:(TRAMP_VALIAS >> 12)
movk \tmp, #:abs_g1_nc:(TRAMP_VALIAS >> 12)
/* 2MB boundary containing the vectors, so we nobble the walk cache */
movk \tmp, #:abs_g0_nc:((TRAMP_VALIAS & ~(SZ_2M - 1)) >> 12)
isb
tlbi vae1, \tmp
dsb nsh
alternative_else_nop_endif
#endif /* CONFIG_QCOM_FALKOR_ERRATUM_1003 */
.endm
.macro tramp_unmap_kernel, tmp
mrs \tmp, ttbr1_el1
sub \tmp, \tmp, #(PAGE_SIZE + RESERVED_TTBR0_SIZE)
orr \tmp, \tmp, #USER_ASID_FLAG
msr ttbr1_el1, \tmp
/*
* We avoid running the post_ttbr_update_workaround here because
* it's only needed by Cavium ThunderX, which requires KPTI to be
* disabled.
*/
.endm
.macro tramp_ventry, regsize = 64
.align 7
1:
.if \regsize == 64
msr tpidrro_el0, x30 // Restored in kernel_ventry
.endif
/*
* Defend against branch aliasing attacks by pushing a dummy
* entry onto the return stack and using a RET instruction to
* enter the full-fat kernel vectors.
*/
bl 2f
b .
2:
tramp_map_kernel x30
#ifdef CONFIG_RANDOMIZE_BASE
adr x30, tramp_vectors + PAGE_SIZE
alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003
ldr x30, [x30]
#else
ldr x30, =vectors
#endif
alternative_if_not ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM
prfm plil1strm, [x30, #(1b - tramp_vectors)]
alternative_else_nop_endif
msr vbar_el1, x30
add x30, x30, #(1b - tramp_vectors)
isb
ret
.endm
.macro tramp_exit, regsize = 64
adr x30, tramp_vectors
msr vbar_el1, x30
tramp_unmap_kernel x30
.if \regsize == 64
mrs x30, far_el1
.endif
eret
sb
.endm
.align 11
SYM_CODE_START_NOALIGN(tramp_vectors)
.space 0x400
tramp_ventry
tramp_ventry
tramp_ventry
tramp_ventry
tramp_ventry 32
tramp_ventry 32
tramp_ventry 32
tramp_ventry 32
SYM_CODE_END(tramp_vectors)
SYM_CODE_START(tramp_exit_native)
tramp_exit
SYM_CODE_END(tramp_exit_native)
SYM_CODE_START(tramp_exit_compat)
tramp_exit 32
SYM_CODE_END(tramp_exit_compat)
.ltorg
.popsection // .entry.tramp.text
#ifdef CONFIG_RANDOMIZE_BASE
.pushsection ".rodata", "a"
.align PAGE_SHIFT
SYM_DATA_START(__entry_tramp_data_start)
.quad vectors
SYM_DATA_END(__entry_tramp_data_start)
.popsection // .rodata
#endif /* CONFIG_RANDOMIZE_BASE */
#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */
/*
* Register switch for AArch64. The callee-saved registers need to be saved
* and restored. On entry:
* x0 = previous task_struct (must be preserved across the switch)
* x1 = next task_struct
* Previous and next are guaranteed not to be the same.
*
*/
SYM_FUNC_START(cpu_switch_to)
mov x10, #THREAD_CPU_CONTEXT
add x8, x0, x10
mov x9, sp
stp x19, x20, [x8], #16 // store callee-saved registers
stp x21, x22, [x8], #16
stp x23, x24, [x8], #16
stp x25, x26, [x8], #16
stp x27, x28, [x8], #16
stp x29, x9, [x8], #16
str lr, [x8]
add x8, x1, x10
ldp x19, x20, [x8], #16 // restore callee-saved registers
ldp x21, x22, [x8], #16
ldp x23, x24, [x8], #16
ldp x25, x26, [x8], #16
ldp x27, x28, [x8], #16
ldp x29, x9, [x8], #16
ldr lr, [x8]
mov sp, x9
msr sp_el0, x1
ptrauth_keys_install_kernel x1, 1, x8, x9, x10
ret
SYM_FUNC_END(cpu_switch_to)
NOKPROBE(cpu_switch_to)
/*
* This is how we return from a fork.
*/
SYM_CODE_START(ret_from_fork)
bl schedule_tail
cbz x19, 1f // not a kernel thread
mov x0, x20
blr x19
1: get_current_task tsk
b ret_to_user
SYM_CODE_END(ret_from_fork)
NOKPROBE(ret_from_fork)
#ifdef CONFIG_ARM_SDE_INTERFACE
#include <asm/sdei.h>
#include <uapi/linux/arm_sdei.h>
.macro sdei_handler_exit exit_mode
/* On success, this call never returns... */
cmp \exit_mode, #SDEI_EXIT_SMC
b.ne 99f
smc #0
b .
99: hvc #0
b .
.endm
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
/*
* The regular SDEI entry point may have been unmapped along with the rest of
* the kernel. This trampoline restores the kernel mapping to make the x1 memory
* argument accessible.
*
* This clobbers x4, __sdei_handler() will restore this from firmware's
* copy.
*/
.ltorg
.pushsection ".entry.tramp.text", "ax"
SYM_CODE_START(__sdei_asm_entry_trampoline)
mrs x4, ttbr1_el1
tbz x4, #USER_ASID_BIT, 1f
tramp_map_kernel tmp=x4
isb
mov x4, xzr
/*
* Use reg->interrupted_regs.addr_limit to remember whether to unmap
* the kernel on exit.
*/
1: str x4, [x1, #(SDEI_EVENT_INTREGS + S_ORIG_ADDR_LIMIT)]
#ifdef CONFIG_RANDOMIZE_BASE
adr x4, tramp_vectors + PAGE_SIZE
add x4, x4, #:lo12:__sdei_asm_trampoline_next_handler
ldr x4, [x4]
#else
ldr x4, =__sdei_asm_handler
#endif
br x4
SYM_CODE_END(__sdei_asm_entry_trampoline)
NOKPROBE(__sdei_asm_entry_trampoline)
/*
* Make the exit call and restore the original ttbr1_el1
*
* x0 & x1: setup for the exit API call
* x2: exit_mode
* x4: struct sdei_registered_event argument from registration time.
*/
SYM_CODE_START(__sdei_asm_exit_trampoline)
ldr x4, [x4, #(SDEI_EVENT_INTREGS + S_ORIG_ADDR_LIMIT)]
cbnz x4, 1f
tramp_unmap_kernel tmp=x4
1: sdei_handler_exit exit_mode=x2
SYM_CODE_END(__sdei_asm_exit_trampoline)
NOKPROBE(__sdei_asm_exit_trampoline)
.ltorg
.popsection // .entry.tramp.text
#ifdef CONFIG_RANDOMIZE_BASE
.pushsection ".rodata", "a"
SYM_DATA_START(__sdei_asm_trampoline_next_handler)
.quad __sdei_asm_handler
SYM_DATA_END(__sdei_asm_trampoline_next_handler)
.popsection // .rodata
#endif /* CONFIG_RANDOMIZE_BASE */
#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */
/*
* Software Delegated Exception entry point.
*
* x0: Event number
* x1: struct sdei_registered_event argument from registration time.
* x2: interrupted PC
* x3: interrupted PSTATE
* x4: maybe clobbered by the trampoline
*
* Firmware has preserved x0->x17 for us, we must save/restore the rest to
* follow SMC-CC. We save (or retrieve) all the registers as the handler may
* want them.
*/
SYM_CODE_START(__sdei_asm_handler)
stp x2, x3, [x1, #SDEI_EVENT_INTREGS + S_PC]
stp x4, x5, [x1, #SDEI_EVENT_INTREGS + 16 * 2]
stp x6, x7, [x1, #SDEI_EVENT_INTREGS + 16 * 3]
stp x8, x9, [x1, #SDEI_EVENT_INTREGS + 16 * 4]
stp x10, x11, [x1, #SDEI_EVENT_INTREGS + 16 * 5]
stp x12, x13, [x1, #SDEI_EVENT_INTREGS + 16 * 6]
stp x14, x15, [x1, #SDEI_EVENT_INTREGS + 16 * 7]
stp x16, x17, [x1, #SDEI_EVENT_INTREGS + 16 * 8]
stp x18, x19, [x1, #SDEI_EVENT_INTREGS + 16 * 9]
stp x20, x21, [x1, #SDEI_EVENT_INTREGS + 16 * 10]
stp x22, x23, [x1, #SDEI_EVENT_INTREGS + 16 * 11]
stp x24, x25, [x1, #SDEI_EVENT_INTREGS + 16 * 12]
stp x26, x27, [x1, #SDEI_EVENT_INTREGS + 16 * 13]
stp x28, x29, [x1, #SDEI_EVENT_INTREGS + 16 * 14]
mov x4, sp
stp lr, x4, [x1, #SDEI_EVENT_INTREGS + S_LR]
mov x19, x1
#ifdef CONFIG_VMAP_STACK
/*
* entry.S may have been using sp as a scratch register, find whether
* this is a normal or critical event and switch to the appropriate
* stack for this CPU.
*/
ldrb w4, [x19, #SDEI_EVENT_PRIORITY]
cbnz w4, 1f
ldr_this_cpu dst=x5, sym=sdei_stack_normal_ptr, tmp=x6
b 2f
1: ldr_this_cpu dst=x5, sym=sdei_stack_critical_ptr, tmp=x6
2: mov x6, #SDEI_STACK_SIZE
add x5, x5, x6
mov sp, x5
#endif
/*
* We may have interrupted userspace, or a guest, or exit-from or
* return-to either of these. We can't trust sp_el0, restore it.
*/
mrs x28, sp_el0
ldr_this_cpu dst=x0, sym=__entry_task, tmp=x1
msr sp_el0, x0
/* If we interrupted the kernel point to the previous stack/frame. */
and x0, x3, #0xc
mrs x1, CurrentEL
cmp x0, x1
csel x29, x29, xzr, eq // fp, or zero
csel x4, x2, xzr, eq // elr, or zero
stp x29, x4, [sp, #-16]!
mov x29, sp
add x0, x19, #SDEI_EVENT_INTREGS
mov x1, x19
bl __sdei_handler
msr sp_el0, x28
/* restore regs >x17 that we clobbered */
mov x4, x19 // keep x4 for __sdei_asm_exit_trampoline
ldp x28, x29, [x4, #SDEI_EVENT_INTREGS + 16 * 14]
ldp x18, x19, [x4, #SDEI_EVENT_INTREGS + 16 * 9]
ldp lr, x1, [x4, #SDEI_EVENT_INTREGS + S_LR]
mov sp, x1
mov x1, x0 // address to complete_and_resume
/* x0 = (x0 <= 1) ? EVENT_COMPLETE:EVENT_COMPLETE_AND_RESUME */
cmp x0, #1
mov_q x2, SDEI_1_0_FN_SDEI_EVENT_COMPLETE
mov_q x3, SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME
csel x0, x2, x3, ls
ldr_l x2, sdei_exit_mode
alternative_if_not ARM64_UNMAP_KERNEL_AT_EL0
sdei_handler_exit exit_mode=x2
alternative_else_nop_endif
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
tramp_alias dst=x5, sym=__sdei_asm_exit_trampoline
br x5
#endif
SYM_CODE_END(__sdei_asm_handler)
NOKPROBE(__sdei_asm_handler)
#endif /* CONFIG_ARM_SDE_INTERFACE */
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