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linux/arch/arm64/kernel/entry.S
Laura Abbott 0b3e336601 arm64: Add support for STACKLEAK gcc plugin 
This adds support for the STACKLEAK gcc plugin to arm64 by implementing
stackleak_check_alloca(), based heavily on the x86 version, and adding the
two helpers used by the stackleak common code: current_top_of_stack() and
on_thread_stack(). The stack erasure calls are made at syscall returns.
Additionally, this disables the plugin in hypervisor and EFI stub code,
which are out of scope for the protection.

Acked-by: Alexander Popov <alex.popov@linux.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-07-26 11:36:34 +01:00

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/*
* Low-level exception handling code
*
* Copyright (C) 2012 ARM Ltd.
* Authors: Catalin Marinas <catalin.marinas@arm.com>
* Will Deacon <will.deacon@arm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#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/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
#ifdef CONFIG_CONTEXT_TRACKING
bl context_tracking_user_exit
#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
alternative_if ARM64_UNMAP_KERNEL_AT_EL0
.if \el == 0
.if \regsize == 64
mrs x30, tpidrro_el0
msr tpidrro_el0, xzr
.else
mov x30, xzr
.endif
.endif
alternative_else_nop_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 to (1 << THREAD_SHIFT).
*/
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 // Ensure MDSCR_EL1.SS is clear,
ldr x19, [tsk, #TSK_TI_FLAGS] // since we can unmask debug
disable_step_tsk x19, x20 // exceptions when scheduling.
apply_ssbd 1, x22, x23
.else
add x21, sp, #S_FRAME_SIZE
get_thread_info 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
/*
* Set sp_el0 to current thread_info.
*/
.if \el == 0
msr sp_el0, tsk
.endif
/*
* Registers that may be useful after this macro is invoked:
*
* 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
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:
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
/*
* ARCH_HAS_MEMBARRIER_SYNC_CORE rely on eret context synchronization
* when returning from IPI handler, and when returning to user-space.
*/
.if \el == 0
alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
bne 4f
msr far_el1, x30
tramp_alias x30, tramp_exit_native
br x30
4:
tramp_alias x30, tramp_exit_compat
br x30
#endif
.else
eret
.endif
.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
/*
* These are the registers used in the syscall handler, and allow us to
* have in theory up to 7 arguments to a function - x0 to x6.
*
* x7 is reserved for the system call number in 32-bit mode.
*/
wsc_nr .req w25 // number of system calls
xsc_nr .req x25 // number of system calls (zero-extended)
wscno .req w26 // syscall number
xscno .req x26 // syscall number (zero-extended)
stbl .req x27 // syscall table pointer
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
.text
/*
* Exception vectors.
*/
.pushsection ".entry.text", "ax"
.align 11
ENTRY(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
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
el0_sync_invalid:
inv_entry 0, BAD_SYNC
ENDPROC(el0_sync_invalid)
el0_irq_invalid:
inv_entry 0, BAD_IRQ
ENDPROC(el0_irq_invalid)
el0_fiq_invalid:
inv_entry 0, BAD_FIQ
ENDPROC(el0_fiq_invalid)
el0_error_invalid:
inv_entry 0, BAD_ERROR
ENDPROC(el0_error_invalid)
#ifdef CONFIG_COMPAT
el0_fiq_invalid_compat:
inv_entry 0, BAD_FIQ, 32
ENDPROC(el0_fiq_invalid_compat)
#endif
el1_sync_invalid:
inv_entry 1, BAD_SYNC
ENDPROC(el1_sync_invalid)
el1_irq_invalid:
inv_entry 1, BAD_IRQ
ENDPROC(el1_irq_invalid)
el1_fiq_invalid:
inv_entry 1, BAD_FIQ
ENDPROC(el1_fiq_invalid)
el1_error_invalid:
inv_entry 1, BAD_ERROR
ENDPROC(el1_error_invalid)
/*
* EL1 mode handlers.
*/
.align 6
el1_sync:
kernel_entry 1
mrs x1, esr_el1 // read the syndrome register
lsr x24, x1, #ESR_ELx_EC_SHIFT // exception class
cmp x24, #ESR_ELx_EC_DABT_CUR // data abort in EL1
b.eq el1_da
cmp x24, #ESR_ELx_EC_IABT_CUR // instruction abort in EL1
b.eq el1_ia
cmp x24, #ESR_ELx_EC_SYS64 // configurable trap
b.eq el1_undef
cmp x24, #ESR_ELx_EC_SP_ALIGN // stack alignment exception
b.eq el1_sp_pc
cmp x24, #ESR_ELx_EC_PC_ALIGN // pc alignment exception
b.eq el1_sp_pc
cmp x24, #ESR_ELx_EC_UNKNOWN // unknown exception in EL1
b.eq el1_undef
cmp x24, #ESR_ELx_EC_BREAKPT_CUR // debug exception in EL1
b.ge el1_dbg
b el1_inv
el1_ia:
/*
* Fall through to the Data abort case
*/
el1_da:
/*
* Data abort handling
*/
mrs x3, far_el1
inherit_daif pstate=x23, tmp=x2
clear_address_tag x0, x3
mov x2, sp // struct pt_regs
bl do_mem_abort
kernel_exit 1
el1_sp_pc:
/*
* Stack or PC alignment exception handling
*/
mrs x0, far_el1
inherit_daif pstate=x23, tmp=x2
mov x2, sp
bl do_sp_pc_abort
ASM_BUG()
el1_undef:
/*
* Undefined instruction
*/
inherit_daif pstate=x23, tmp=x2
mov x0, sp
bl do_undefinstr
ASM_BUG()
el1_dbg:
/*
* Debug exception handling
*/
cmp x24, #ESR_ELx_EC_BRK64 // if BRK64
cinc x24, x24, eq // set bit '0'
tbz x24, #0, el1_inv // EL1 only
mrs x0, far_el1
mov x2, sp // struct pt_regs
bl do_debug_exception
kernel_exit 1
el1_inv:
// TODO: add support for undefined instructions in kernel mode
inherit_daif pstate=x23, tmp=x2
mov x0, sp
mov x2, x1
mov x1, #BAD_SYNC
bl bad_mode
ASM_BUG()
ENDPROC(el1_sync)
.align 6
el1_irq:
kernel_entry 1
enable_da_f
#ifdef CONFIG_TRACE_IRQFLAGS
bl trace_hardirqs_off
#endif
irq_handler
#ifdef CONFIG_PREEMPT
ldr w24, [tsk, #TSK_TI_PREEMPT] // get preempt count
cbnz w24, 1f // preempt count != 0
ldr x0, [tsk, #TSK_TI_FLAGS] // get flags
tbz x0, #TIF_NEED_RESCHED, 1f // needs rescheduling?
bl el1_preempt
1:
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
bl trace_hardirqs_on
#endif
kernel_exit 1
ENDPROC(el1_irq)
#ifdef CONFIG_PREEMPT
el1_preempt:
mov x24, lr
1: bl preempt_schedule_irq // irq en/disable is done inside
ldr x0, [tsk, #TSK_TI_FLAGS] // get new tasks TI_FLAGS
tbnz x0, #TIF_NEED_RESCHED, 1b // needs rescheduling?
ret x24
#endif
/*
* EL0 mode handlers.
*/
.align 6
el0_sync:
kernel_entry 0
mrs x25, esr_el1 // read the syndrome register
lsr x24, x25, #ESR_ELx_EC_SHIFT // exception class
cmp x24, #ESR_ELx_EC_SVC64 // SVC in 64-bit state
b.eq el0_svc
cmp x24, #ESR_ELx_EC_DABT_LOW // data abort in EL0
b.eq el0_da
cmp x24, #ESR_ELx_EC_IABT_LOW // instruction abort in EL0
b.eq el0_ia
cmp x24, #ESR_ELx_EC_FP_ASIMD // FP/ASIMD access
b.eq el0_fpsimd_acc
cmp x24, #ESR_ELx_EC_SVE // SVE access
b.eq el0_sve_acc
cmp x24, #ESR_ELx_EC_FP_EXC64 // FP/ASIMD exception
b.eq el0_fpsimd_exc
cmp x24, #ESR_ELx_EC_SYS64 // configurable trap
b.eq el0_sys
cmp x24, #ESR_ELx_EC_SP_ALIGN // stack alignment exception
b.eq el0_sp_pc
cmp x24, #ESR_ELx_EC_PC_ALIGN // pc alignment exception
b.eq el0_sp_pc
cmp x24, #ESR_ELx_EC_UNKNOWN // unknown exception in EL0
b.eq el0_undef
cmp x24, #ESR_ELx_EC_BREAKPT_LOW // debug exception in EL0
b.ge el0_dbg
b el0_inv
#ifdef CONFIG_COMPAT
.align 6
el0_sync_compat:
kernel_entry 0, 32
mrs x25, esr_el1 // read the syndrome register
lsr x24, x25, #ESR_ELx_EC_SHIFT // exception class
cmp x24, #ESR_ELx_EC_SVC32 // SVC in 32-bit state
b.eq el0_svc_compat
cmp x24, #ESR_ELx_EC_DABT_LOW // data abort in EL0
b.eq el0_da
cmp x24, #ESR_ELx_EC_IABT_LOW // instruction abort in EL0
b.eq el0_ia
cmp x24, #ESR_ELx_EC_FP_ASIMD // FP/ASIMD access
b.eq el0_fpsimd_acc
cmp x24, #ESR_ELx_EC_FP_EXC32 // FP/ASIMD exception
b.eq el0_fpsimd_exc
cmp x24, #ESR_ELx_EC_PC_ALIGN // pc alignment exception
b.eq el0_sp_pc
cmp x24, #ESR_ELx_EC_UNKNOWN // unknown exception in EL0
b.eq el0_undef
cmp x24, #ESR_ELx_EC_CP15_32 // CP15 MRC/MCR trap
b.eq el0_undef
cmp x24, #ESR_ELx_EC_CP15_64 // CP15 MRRC/MCRR trap
b.eq el0_undef
cmp x24, #ESR_ELx_EC_CP14_MR // CP14 MRC/MCR trap
b.eq el0_undef
cmp x24, #ESR_ELx_EC_CP14_LS // CP14 LDC/STC trap
b.eq el0_undef
cmp x24, #ESR_ELx_EC_CP14_64 // CP14 MRRC/MCRR trap
b.eq el0_undef
cmp x24, #ESR_ELx_EC_BREAKPT_LOW // debug exception in EL0
b.ge el0_dbg
b el0_inv
el0_svc_compat:
mov x0, sp
bl el0_svc_compat_handler
b ret_to_user
.align 6
el0_irq_compat:
kernel_entry 0, 32
b el0_irq_naked
el0_error_compat:
kernel_entry 0, 32
b el0_error_naked
#endif
el0_da:
/*
* Data abort handling
*/
mrs x26, far_el1
enable_daif
ct_user_exit
clear_address_tag x0, x26
mov x1, x25
mov x2, sp
bl do_mem_abort
b ret_to_user
el0_ia:
/*
* Instruction abort handling
*/
mrs x26, far_el1
enable_da_f
#ifdef CONFIG_TRACE_IRQFLAGS
bl trace_hardirqs_off
#endif
ct_user_exit
mov x0, x26
mov x1, x25
mov x2, sp
bl do_el0_ia_bp_hardening
b ret_to_user
el0_fpsimd_acc:
/*
* Floating Point or Advanced SIMD access
*/
enable_daif
ct_user_exit
mov x0, x25
mov x1, sp
bl do_fpsimd_acc
b ret_to_user
el0_sve_acc:
/*
* Scalable Vector Extension access
*/
enable_daif
ct_user_exit
mov x0, x25
mov x1, sp
bl do_sve_acc
b ret_to_user
el0_fpsimd_exc:
/*
* Floating Point, Advanced SIMD or SVE exception
*/
enable_daif
ct_user_exit
mov x0, x25
mov x1, sp
bl do_fpsimd_exc
b ret_to_user
el0_sp_pc:
/*
* Stack or PC alignment exception handling
*/
mrs x26, far_el1
enable_da_f
#ifdef CONFIG_TRACE_IRQFLAGS
bl trace_hardirqs_off
#endif
ct_user_exit
mov x0, x26
mov x1, x25
mov x2, sp
bl do_sp_pc_abort
b ret_to_user
el0_undef:
/*
* Undefined instruction
*/
enable_daif
ct_user_exit
mov x0, sp
bl do_undefinstr
b ret_to_user
el0_sys:
/*
* System instructions, for trapped cache maintenance instructions
*/
enable_daif
ct_user_exit
mov x0, x25
mov x1, sp
bl do_sysinstr
b ret_to_user
el0_dbg:
/*
* Debug exception handling
*/
tbnz x24, #0, el0_inv // EL0 only
mrs x0, far_el1
mov x1, x25
mov x2, sp
bl do_debug_exception
enable_daif
ct_user_exit
b ret_to_user
el0_inv:
enable_daif
ct_user_exit
mov x0, sp
mov x1, #BAD_SYNC
mov x2, x25
bl bad_el0_sync
b ret_to_user
ENDPROC(el0_sync)
.align 6
el0_irq:
kernel_entry 0
el0_irq_naked:
enable_da_f
#ifdef CONFIG_TRACE_IRQFLAGS
bl trace_hardirqs_off
#endif
ct_user_exit
#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
ENDPROC(el0_irq)
el1_error:
kernel_entry 1
mrs x1, esr_el1
enable_dbg
mov x0, sp
bl do_serror
kernel_exit 1
ENDPROC(el1_error)
el0_error:
kernel_entry 0
el0_error_naked:
mrs x1, esr_el1
enable_dbg
mov x0, sp
bl do_serror
enable_daif
ct_user_exit
b ret_to_user
ENDPROC(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
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)
/*
* SVC handler.
*/
.align 6
el0_svc:
mov x0, sp
bl el0_svc_handler
b ret_to_user
ENDPROC(el0_svc)
.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
prfm plil1strm, [x30, #(1b - tramp_vectors)]
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
.endm
.align 11
ENTRY(tramp_vectors)
.space 0x400
tramp_ventry
tramp_ventry
tramp_ventry
tramp_ventry
tramp_ventry 32
tramp_ventry 32
tramp_ventry 32
tramp_ventry 32
END(tramp_vectors)
ENTRY(tramp_exit_native)
tramp_exit
END(tramp_exit_native)
ENTRY(tramp_exit_compat)
tramp_exit 32
END(tramp_exit_compat)
.ltorg
.popsection // .entry.tramp.text
#ifdef CONFIG_RANDOMIZE_BASE
.pushsection ".rodata", "a"
.align PAGE_SHIFT
.globl __entry_tramp_data_start
__entry_tramp_data_start:
.quad vectors
.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.
*
*/
ENTRY(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
ret
ENDPROC(cpu_switch_to)
NOKPROBE(cpu_switch_to)
/*
* This is how we return from a fork.
*/
ENTRY(ret_from_fork)
bl schedule_tail
cbz x19, 1f // not a kernel thread
mov x0, x20
blr x19
1: get_thread_info tsk
b ret_to_user
ENDPROC(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"
ENTRY(__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
ENDPROC(__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.
*/
ENTRY(__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
ENDPROC(__sdei_asm_exit_trampoline)
NOKPROBE(__sdei_asm_exit_trampoline)
.ltorg
.popsection // .entry.tramp.text
#ifdef CONFIG_RANDOMIZE_BASE
.pushsection ".rodata", "a"
__sdei_asm_trampoline_next_handler:
.quad __sdei_asm_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.
*/
ENTRY(__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
ENDPROC(__sdei_asm_handler)
NOKPROBE(__sdei_asm_handler)
#endif /* CONFIG_ARM_SDE_INTERFACE */
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