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linux/arch/arm64/kernel/entry-common.c
Mark Rutland 024f4b2e1f arm64: entry: avoid kprobe recursion 
The cortex_a76_erratum_1463225_debug_handler() function is called when
handling debug exceptions (and synchronous exceptions from BRK
instructions), and so is called when a probed function executes. If the
compiler does not inline cortex_a76_erratum_1463225_debug_handler(), it
can be probed.

If cortex_a76_erratum_1463225_debug_handler() is probed, any debug
exception or software breakpoint exception will result in recursive
exceptions leading to a stack overflow. This can be triggered with the
ftrace multiple_probes selftest, and as per the example splat below.

This is a regression caused by commit:

  6459b84697 ("arm64: entry: consolidate Cortex-A76 erratum 1463225 workaround")

... which removed the NOKPROBE_SYMBOL() annotation associated with the
function.

My intent was that cortex_a76_erratum_1463225_debug_handler() would be
inlined into its caller, el1_dbg(), which is marked noinstr and cannot
be probed. Mark cortex_a76_erratum_1463225_debug_handler() as
__always_inline to ensure this.

Example splat prior to this patch (with recursive entries elided):

| # echo p cortex_a76_erratum_1463225_debug_handler > /sys/kernel/debug/tracing/kprobe_events
| # echo p do_el0_svc >> /sys/kernel/debug/tracing/kprobe_events
| # echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable
| Insufficient stack space to handle exception!
| ESR: 0x0000000096000047 -- DABT (current EL)
| FAR: 0xffff800009cefff0
| Task stack:     [0xffff800009cf0000..0xffff800009cf4000]
| IRQ stack:      [0xffff800008000000..0xffff800008004000]
| Overflow stack: [0xffff00007fbc00f0..0xffff00007fbc10f0]
| CPU: 0 PID: 145 Comm: sh Not tainted 6.0.0 #2
| Hardware name: linux,dummy-virt (DT)
| pstate: 604003c5 (nZCv DAIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
| pc : arm64_enter_el1_dbg+0x4/0x20
| lr : el1_dbg+0x24/0x5c
| sp : ffff800009cf0000
| x29: ffff800009cf0000 x28: ffff000002c74740 x27: 0000000000000000
| x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000
| x23: 00000000604003c5 x22: ffff80000801745c x21: 0000aaaac95ac068
| x20: 00000000f2000004 x19: ffff800009cf0040 x18: 0000000000000000
| x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
| x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
| x11: 0000000000000010 x10: ffff800008c87190 x9 : ffff800008ca00d0
| x8 : 000000000000003c x7 : 0000000000000000 x6 : 0000000000000000
| x5 : 0000000000000000 x4 : 0000000000000000 x3 : 00000000000043a4
| x2 : 00000000f2000004 x1 : 00000000f2000004 x0 : ffff800009cf0040
| Kernel panic - not syncing: kernel stack overflow
| CPU: 0 PID: 145 Comm: sh Not tainted 6.0.0 #2
| Hardware name: linux,dummy-virt (DT)
| Call trace:
|  dump_backtrace+0xe4/0x104
|  show_stack+0x18/0x4c
|  dump_stack_lvl+0x64/0x7c
|  dump_stack+0x18/0x38
|  panic+0x14c/0x338
|  test_taint+0x0/0x2c
|  panic_bad_stack+0x104/0x118
|  handle_bad_stack+0x34/0x48
|  __bad_stack+0x78/0x7c
|  arm64_enter_el1_dbg+0x4/0x20
|  el1h_64_sync_handler+0x40/0x98
|  el1h_64_sync+0x64/0x68
|  cortex_a76_erratum_1463225_debug_handler+0x0/0x34
...
|  el1h_64_sync_handler+0x40/0x98
|  el1h_64_sync+0x64/0x68
|  cortex_a76_erratum_1463225_debug_handler+0x0/0x34
...
|  el1h_64_sync_handler+0x40/0x98
|  el1h_64_sync+0x64/0x68
|  cortex_a76_erratum_1463225_debug_handler+0x0/0x34
|  el1h_64_sync_handler+0x40/0x98
|  el1h_64_sync+0x64/0x68
|  do_el0_svc+0x0/0x28
|  el0t_64_sync_handler+0x84/0xf0
|  el0t_64_sync+0x18c/0x190
| Kernel Offset: disabled
| CPU features: 0x0080,00005021,19001080
| Memory Limit: none
| ---[ end Kernel panic - not syncing: kernel stack overflow ]---

With this patch, cortex_a76_erratum_1463225_debug_handler() is inlined
into el1_dbg(), and el1_dbg() cannot be probed:

| # echo p cortex_a76_erratum_1463225_debug_handler > /sys/kernel/debug/tracing/kprobe_events
| sh: write error: No such file or directory
| # grep -w cortex_a76_erratum_1463225_debug_handler /proc/kallsyms | wc -l
| 0
| # echo p el1_dbg > /sys/kernel/debug/tracing/kprobe_events
| sh: write error: Invalid argument
| # grep -w el1_dbg /proc/kallsyms | wc -l
| 1

Fixes: 6459b84697 ("arm64: entry: consolidate Cortex-A76 erratum 1463225 workaround")
Cc: <stable@vger.kernel.org> # 5.12.x
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20221017090157.2881408-1-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2022-11-01 17:43:31 +00:00

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// SPDX-License-Identifier: GPL-2.0
/*
* Exception handling code
*
* Copyright (C) 2019 ARM Ltd.
*/
#include <linux/context_tracking.h>
#include <linux/kasan.h>
#include <linux/linkage.h>
#include <linux/lockdep.h>
#include <linux/ptrace.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/thread_info.h>
#include <asm/cpufeature.h>
#include <asm/daifflags.h>
#include <asm/esr.h>
#include <asm/exception.h>
#include <asm/irq_regs.h>
#include <asm/kprobes.h>
#include <asm/mmu.h>
#include <asm/processor.h>
#include <asm/sdei.h>
#include <asm/stacktrace.h>
#include <asm/sysreg.h>
#include <asm/system_misc.h>
/*
* Handle IRQ/context state management when entering from kernel mode.
* Before this function is called it is not safe to call regular kernel code,
* intrumentable code, or any code which may trigger an exception.
*
* This is intended to match the logic in irqentry_enter(), handling the kernel
* mode transitions only.
*/
static __always_inline void __enter_from_kernel_mode(struct pt_regs *regs)
{
regs->exit_rcu = false;
if (!IS_ENABLED(CONFIG_TINY_RCU) && is_idle_task(current)) {
lockdep_hardirqs_off(CALLER_ADDR0);
ct_irq_enter();
trace_hardirqs_off_finish();
regs->exit_rcu = true;
return;
}
lockdep_hardirqs_off(CALLER_ADDR0);
rcu_irq_enter_check_tick();
trace_hardirqs_off_finish();
}
static void noinstr enter_from_kernel_mode(struct pt_regs *regs)
{
__enter_from_kernel_mode(regs);
mte_check_tfsr_entry();
mte_disable_tco_entry(current);
}
/*
* Handle IRQ/context state management when exiting to kernel mode.
* After this function returns it is not safe to call regular kernel code,
* intrumentable code, or any code which may trigger an exception.
*
* This is intended to match the logic in irqentry_exit(), handling the kernel
* mode transitions only, and with preemption handled elsewhere.
*/
static __always_inline void __exit_to_kernel_mode(struct pt_regs *regs)
{
lockdep_assert_irqs_disabled();
if (interrupts_enabled(regs)) {
if (regs->exit_rcu) {
trace_hardirqs_on_prepare();
lockdep_hardirqs_on_prepare();
ct_irq_exit();
lockdep_hardirqs_on(CALLER_ADDR0);
return;
}
trace_hardirqs_on();
} else {
if (regs->exit_rcu)
ct_irq_exit();
}
}
static void noinstr exit_to_kernel_mode(struct pt_regs *regs)
{
mte_check_tfsr_exit();
__exit_to_kernel_mode(regs);
}
/*
* Handle IRQ/context state management when entering from user mode.
* Before this function is called it is not safe to call regular kernel code,
* intrumentable code, or any code which may trigger an exception.
*/
static __always_inline void __enter_from_user_mode(void)
{
lockdep_hardirqs_off(CALLER_ADDR0);
CT_WARN_ON(ct_state() != CONTEXT_USER);
user_exit_irqoff();
trace_hardirqs_off_finish();
mte_disable_tco_entry(current);
}
static __always_inline void enter_from_user_mode(struct pt_regs *regs)
{
__enter_from_user_mode();
}
/*
* Handle IRQ/context state management when exiting to user mode.
* After this function returns it is not safe to call regular kernel code,
* intrumentable code, or any code which may trigger an exception.
*/
static __always_inline void __exit_to_user_mode(void)
{
trace_hardirqs_on_prepare();
lockdep_hardirqs_on_prepare();
user_enter_irqoff();
lockdep_hardirqs_on(CALLER_ADDR0);
}
static __always_inline void prepare_exit_to_user_mode(struct pt_regs *regs)
{
unsigned long flags;
local_daif_mask();
flags = read_thread_flags();
if (unlikely(flags & _TIF_WORK_MASK))
do_notify_resume(regs, flags);
}
static __always_inline void exit_to_user_mode(struct pt_regs *regs)
{
prepare_exit_to_user_mode(regs);
mte_check_tfsr_exit();
__exit_to_user_mode();
}
asmlinkage void noinstr asm_exit_to_user_mode(struct pt_regs *regs)
{
exit_to_user_mode(regs);
}
/*
* Handle IRQ/context state management when entering an NMI from user/kernel
* mode. Before this function is called it is not safe to call regular kernel
* code, intrumentable code, or any code which may trigger an exception.
*/
static void noinstr arm64_enter_nmi(struct pt_regs *regs)
{
regs->lockdep_hardirqs = lockdep_hardirqs_enabled();
__nmi_enter();
lockdep_hardirqs_off(CALLER_ADDR0);
lockdep_hardirq_enter();
ct_nmi_enter();
trace_hardirqs_off_finish();
ftrace_nmi_enter();
}
/*
* Handle IRQ/context state management when exiting an NMI from user/kernel
* mode. After this function returns it is not safe to call regular kernel
* code, intrumentable code, or any code which may trigger an exception.
*/
static void noinstr arm64_exit_nmi(struct pt_regs *regs)
{
bool restore = regs->lockdep_hardirqs;
ftrace_nmi_exit();
if (restore) {
trace_hardirqs_on_prepare();
lockdep_hardirqs_on_prepare();
}
ct_nmi_exit();
lockdep_hardirq_exit();
if (restore)
lockdep_hardirqs_on(CALLER_ADDR0);
__nmi_exit();
}
/*
* Handle IRQ/context state management when entering a debug exception from
* kernel mode. Before this function is called it is not safe to call regular
* kernel code, intrumentable code, or any code which may trigger an exception.
*/
static void noinstr arm64_enter_el1_dbg(struct pt_regs *regs)
{
regs->lockdep_hardirqs = lockdep_hardirqs_enabled();
lockdep_hardirqs_off(CALLER_ADDR0);
ct_nmi_enter();
trace_hardirqs_off_finish();
}
/*
* Handle IRQ/context state management when exiting a debug exception from
* kernel mode. After this function returns it is not safe to call regular
* kernel code, intrumentable code, or any code which may trigger an exception.
*/
static void noinstr arm64_exit_el1_dbg(struct pt_regs *regs)
{
bool restore = regs->lockdep_hardirqs;
if (restore) {
trace_hardirqs_on_prepare();
lockdep_hardirqs_on_prepare();
}
ct_nmi_exit();
if (restore)
lockdep_hardirqs_on(CALLER_ADDR0);
}
#ifdef CONFIG_PREEMPT_DYNAMIC
DEFINE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
#define need_irq_preemption() \
(static_branch_unlikely(&sk_dynamic_irqentry_exit_cond_resched))
#else
#define need_irq_preemption() (IS_ENABLED(CONFIG_PREEMPTION))
#endif
static void __sched arm64_preempt_schedule_irq(void)
{
if (!need_irq_preemption())
return;
/*
* Note: thread_info::preempt_count includes both thread_info::count
* and thread_info::need_resched, and is not equivalent to
* preempt_count().
*/
if (READ_ONCE(current_thread_info()->preempt_count) != 0)
return;
/*
* DAIF.DA are cleared at the start of IRQ/FIQ handling, and when GIC
* priority masking is used the GIC irqchip driver will clear DAIF.IF
* using gic_arch_enable_irqs() for normal IRQs. If anything is set in
* DAIF we must have handled an NMI, so skip preemption.
*/
if (system_uses_irq_prio_masking() && read_sysreg(daif))
return;
/*
* Preempting a task from an IRQ means we leave copies of PSTATE
* on the stack. cpufeature's enable calls may modify PSTATE, but
* resuming one of these preempted tasks would undo those changes.
*
* Only allow a task to be preempted once cpufeatures have been
* enabled.
*/
if (system_capabilities_finalized())
preempt_schedule_irq();
}
static void do_interrupt_handler(struct pt_regs *regs,
void (*handler)(struct pt_regs *))
{
struct pt_regs *old_regs = set_irq_regs(regs);
if (on_thread_stack())
call_on_irq_stack(regs, handler);
else
handler(regs);
set_irq_regs(old_regs);
}
extern void (*handle_arch_irq)(struct pt_regs *);
extern void (*handle_arch_fiq)(struct pt_regs *);
static void noinstr __panic_unhandled(struct pt_regs *regs, const char *vector,
unsigned long esr)
{
arm64_enter_nmi(regs);
console_verbose();
pr_crit("Unhandled %s exception on CPU%d, ESR 0x%016lx -- %s\n",
vector, smp_processor_id(), esr,
esr_get_class_string(esr));
__show_regs(regs);
panic("Unhandled exception");
}
#define UNHANDLED(el, regsize, vector) \
asmlinkage void noinstr el##_##regsize##_##vector##_handler(struct pt_regs *regs) \
{ \
const char *desc = #regsize "-bit " #el " " #vector; \
__panic_unhandled(regs, desc, read_sysreg(esr_el1)); \
}
#ifdef CONFIG_ARM64_ERRATUM_1463225
static DEFINE_PER_CPU(int, __in_cortex_a76_erratum_1463225_wa);
static void cortex_a76_erratum_1463225_svc_handler(void)
{
u32 reg, val;
if (!unlikely(test_thread_flag(TIF_SINGLESTEP)))
return;
if (!unlikely(this_cpu_has_cap(ARM64_WORKAROUND_1463225)))
return;
__this_cpu_write(__in_cortex_a76_erratum_1463225_wa, 1);
reg = read_sysreg(mdscr_el1);
val = reg | DBG_MDSCR_SS | DBG_MDSCR_KDE;
write_sysreg(val, mdscr_el1);
asm volatile("msr daifclr, #8");
isb();
/* We will have taken a single-step exception by this point */
write_sysreg(reg, mdscr_el1);
__this_cpu_write(__in_cortex_a76_erratum_1463225_wa, 0);
}
static __always_inline bool
cortex_a76_erratum_1463225_debug_handler(struct pt_regs *regs)
{
if (!__this_cpu_read(__in_cortex_a76_erratum_1463225_wa))
return false;
/*
* We've taken a dummy step exception from the kernel to ensure
* that interrupts are re-enabled on the syscall path. Return back
* to cortex_a76_erratum_1463225_svc_handler() with debug exceptions
* masked so that we can safely restore the mdscr and get on with
* handling the syscall.
*/
regs->pstate |= PSR_D_BIT;
return true;
}
#else /* CONFIG_ARM64_ERRATUM_1463225 */
static void cortex_a76_erratum_1463225_svc_handler(void) { }
static bool cortex_a76_erratum_1463225_debug_handler(struct pt_regs *regs)
{
return false;
}
#endif /* CONFIG_ARM64_ERRATUM_1463225 */
UNHANDLED(el1t, 64, sync)
UNHANDLED(el1t, 64, irq)
UNHANDLED(el1t, 64, fiq)
UNHANDLED(el1t, 64, error)
static void noinstr el1_abort(struct pt_regs *regs, unsigned long esr)
{
unsigned long far = read_sysreg(far_el1);
enter_from_kernel_mode(regs);
local_daif_inherit(regs);
do_mem_abort(far, esr, regs);
local_daif_mask();
exit_to_kernel_mode(regs);
}
static void noinstr el1_pc(struct pt_regs *regs, unsigned long esr)
{
unsigned long far = read_sysreg(far_el1);
enter_from_kernel_mode(regs);
local_daif_inherit(regs);
do_sp_pc_abort(far, esr, regs);
local_daif_mask();
exit_to_kernel_mode(regs);
}
static void noinstr el1_undef(struct pt_regs *regs, unsigned long esr)
{
enter_from_kernel_mode(regs);
local_daif_inherit(regs);
do_undefinstr(regs, esr);
local_daif_mask();
exit_to_kernel_mode(regs);
}
static void noinstr el1_bti(struct pt_regs *regs, unsigned long esr)
{
enter_from_kernel_mode(regs);
local_daif_inherit(regs);
do_el1_bti(regs, esr);
local_daif_mask();
exit_to_kernel_mode(regs);
}
static void noinstr el1_dbg(struct pt_regs *regs, unsigned long esr)
{
unsigned long far = read_sysreg(far_el1);
arm64_enter_el1_dbg(regs);
if (!cortex_a76_erratum_1463225_debug_handler(regs))
do_debug_exception(far, esr, regs);
arm64_exit_el1_dbg(regs);
}
static void noinstr el1_fpac(struct pt_regs *regs, unsigned long esr)
{
enter_from_kernel_mode(regs);
local_daif_inherit(regs);
do_el1_fpac(regs, esr);
local_daif_mask();
exit_to_kernel_mode(regs);
}
asmlinkage void noinstr el1h_64_sync_handler(struct pt_regs *regs)
{
unsigned long esr = read_sysreg(esr_el1);
switch (ESR_ELx_EC(esr)) {
case ESR_ELx_EC_DABT_CUR:
case ESR_ELx_EC_IABT_CUR:
el1_abort(regs, esr);
break;
/*
* We don't handle ESR_ELx_EC_SP_ALIGN, since we will have hit a
* recursive exception when trying to push the initial pt_regs.
*/
case ESR_ELx_EC_PC_ALIGN:
el1_pc(regs, esr);
break;
case ESR_ELx_EC_SYS64:
case ESR_ELx_EC_UNKNOWN:
el1_undef(regs, esr);
break;
case ESR_ELx_EC_BTI:
el1_bti(regs, esr);
break;
case ESR_ELx_EC_BREAKPT_CUR:
case ESR_ELx_EC_SOFTSTP_CUR:
case ESR_ELx_EC_WATCHPT_CUR:
case ESR_ELx_EC_BRK64:
el1_dbg(regs, esr);
break;
case ESR_ELx_EC_FPAC:
el1_fpac(regs, esr);
break;
default:
__panic_unhandled(regs, "64-bit el1h sync", esr);
}
}
static __always_inline void __el1_pnmi(struct pt_regs *regs,
void (*handler)(struct pt_regs *))
{
arm64_enter_nmi(regs);
do_interrupt_handler(regs, handler);
arm64_exit_nmi(regs);
}
static __always_inline void __el1_irq(struct pt_regs *regs,
void (*handler)(struct pt_regs *))
{
enter_from_kernel_mode(regs);
irq_enter_rcu();
do_interrupt_handler(regs, handler);
irq_exit_rcu();
arm64_preempt_schedule_irq();
exit_to_kernel_mode(regs);
}
static void noinstr el1_interrupt(struct pt_regs *regs,
void (*handler)(struct pt_regs *))
{
write_sysreg(DAIF_PROCCTX_NOIRQ, daif);
if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
__el1_pnmi(regs, handler);
else
__el1_irq(regs, handler);
}
asmlinkage void noinstr el1h_64_irq_handler(struct pt_regs *regs)
{
el1_interrupt(regs, handle_arch_irq);
}
asmlinkage void noinstr el1h_64_fiq_handler(struct pt_regs *regs)
{
el1_interrupt(regs, handle_arch_fiq);
}
asmlinkage void noinstr el1h_64_error_handler(struct pt_regs *regs)
{
unsigned long esr = read_sysreg(esr_el1);
local_daif_restore(DAIF_ERRCTX);
arm64_enter_nmi(regs);
do_serror(regs, esr);
arm64_exit_nmi(regs);
}
static void noinstr el0_da(struct pt_regs *regs, unsigned long esr)
{
unsigned long far = read_sysreg(far_el1);
enter_from_user_mode(regs);
local_daif_restore(DAIF_PROCCTX);
do_mem_abort(far, esr, regs);
exit_to_user_mode(regs);
}
static void noinstr el0_ia(struct pt_regs *regs, unsigned long esr)
{
unsigned long far = read_sysreg(far_el1);
/*
* We've taken an instruction abort from userspace and not yet
* re-enabled IRQs. If the address is a kernel address, apply
* BP hardening prior to enabling IRQs and pre-emption.
*/
if (!is_ttbr0_addr(far))
arm64_apply_bp_hardening();
enter_from_user_mode(regs);
local_daif_restore(DAIF_PROCCTX);
do_mem_abort(far, esr, regs);
exit_to_user_mode(regs);
}
static void noinstr el0_fpsimd_acc(struct pt_regs *regs, unsigned long esr)
{
enter_from_user_mode(regs);
local_daif_restore(DAIF_PROCCTX);
do_fpsimd_acc(esr, regs);
exit_to_user_mode(regs);
}
static void noinstr el0_sve_acc(struct pt_regs *regs, unsigned long esr)
{
enter_from_user_mode(regs);
local_daif_restore(DAIF_PROCCTX);
do_sve_acc(esr, regs);
exit_to_user_mode(regs);
}
static void noinstr el0_sme_acc(struct pt_regs *regs, unsigned long esr)
{
enter_from_user_mode(regs);
local_daif_restore(DAIF_PROCCTX);
do_sme_acc(esr, regs);
exit_to_user_mode(regs);
}
static void noinstr el0_fpsimd_exc(struct pt_regs *regs, unsigned long esr)
{
enter_from_user_mode(regs);
local_daif_restore(DAIF_PROCCTX);
do_fpsimd_exc(esr, regs);
exit_to_user_mode(regs);
}
static void noinstr el0_sys(struct pt_regs *regs, unsigned long esr)
{
enter_from_user_mode(regs);
local_daif_restore(DAIF_PROCCTX);
do_sysinstr(esr, regs);
exit_to_user_mode(regs);
}
static void noinstr el0_pc(struct pt_regs *regs, unsigned long esr)
{
unsigned long far = read_sysreg(far_el1);
if (!is_ttbr0_addr(instruction_pointer(regs)))
arm64_apply_bp_hardening();
enter_from_user_mode(regs);
local_daif_restore(DAIF_PROCCTX);
do_sp_pc_abort(far, esr, regs);
exit_to_user_mode(regs);
}
static void noinstr el0_sp(struct pt_regs *regs, unsigned long esr)
{
enter_from_user_mode(regs);
local_daif_restore(DAIF_PROCCTX);
do_sp_pc_abort(regs->sp, esr, regs);
exit_to_user_mode(regs);
}
static void noinstr el0_undef(struct pt_regs *regs, unsigned long esr)
{
enter_from_user_mode(regs);
local_daif_restore(DAIF_PROCCTX);
do_undefinstr(regs, esr);
exit_to_user_mode(regs);
}
static void noinstr el0_bti(struct pt_regs *regs)
{
enter_from_user_mode(regs);
local_daif_restore(DAIF_PROCCTX);
do_el0_bti(regs);
exit_to_user_mode(regs);
}
static void noinstr el0_inv(struct pt_regs *regs, unsigned long esr)
{
enter_from_user_mode(regs);
local_daif_restore(DAIF_PROCCTX);
bad_el0_sync(regs, 0, esr);
exit_to_user_mode(regs);
}
static void noinstr el0_dbg(struct pt_regs *regs, unsigned long esr)
{
/* Only watchpoints write FAR_EL1, otherwise its UNKNOWN */
unsigned long far = read_sysreg(far_el1);
enter_from_user_mode(regs);
do_debug_exception(far, esr, regs);
local_daif_restore(DAIF_PROCCTX);
exit_to_user_mode(regs);
}
static void noinstr el0_svc(struct pt_regs *regs)
{
enter_from_user_mode(regs);
cortex_a76_erratum_1463225_svc_handler();
do_el0_svc(regs);
exit_to_user_mode(regs);
}
static void noinstr el0_fpac(struct pt_regs *regs, unsigned long esr)
{
enter_from_user_mode(regs);
local_daif_restore(DAIF_PROCCTX);
do_el0_fpac(regs, esr);
exit_to_user_mode(regs);
}
asmlinkage void noinstr el0t_64_sync_handler(struct pt_regs *regs)
{
unsigned long esr = read_sysreg(esr_el1);
switch (ESR_ELx_EC(esr)) {
case ESR_ELx_EC_SVC64:
el0_svc(regs);
break;
case ESR_ELx_EC_DABT_LOW:
el0_da(regs, esr);
break;
case ESR_ELx_EC_IABT_LOW:
el0_ia(regs, esr);
break;
case ESR_ELx_EC_FP_ASIMD:
el0_fpsimd_acc(regs, esr);
break;
case ESR_ELx_EC_SVE:
el0_sve_acc(regs, esr);
break;
case ESR_ELx_EC_SME:
el0_sme_acc(regs, esr);
break;
case ESR_ELx_EC_FP_EXC64:
el0_fpsimd_exc(regs, esr);
break;
case ESR_ELx_EC_SYS64:
case ESR_ELx_EC_WFx:
el0_sys(regs, esr);
break;
case ESR_ELx_EC_SP_ALIGN:
el0_sp(regs, esr);
break;
case ESR_ELx_EC_PC_ALIGN:
el0_pc(regs, esr);
break;
case ESR_ELx_EC_UNKNOWN:
el0_undef(regs, esr);
break;
case ESR_ELx_EC_BTI:
el0_bti(regs);
break;
case ESR_ELx_EC_BREAKPT_LOW:
case ESR_ELx_EC_SOFTSTP_LOW:
case ESR_ELx_EC_WATCHPT_LOW:
case ESR_ELx_EC_BRK64:
el0_dbg(regs, esr);
break;
case ESR_ELx_EC_FPAC:
el0_fpac(regs, esr);
break;
default:
el0_inv(regs, esr);
}
}
static void noinstr el0_interrupt(struct pt_regs *regs,
void (*handler)(struct pt_regs *))
{
enter_from_user_mode(regs);
write_sysreg(DAIF_PROCCTX_NOIRQ, daif);
if (regs->pc & BIT(55))
arm64_apply_bp_hardening();
irq_enter_rcu();
do_interrupt_handler(regs, handler);
irq_exit_rcu();
exit_to_user_mode(regs);
}
static void noinstr __el0_irq_handler_common(struct pt_regs *regs)
{
el0_interrupt(regs, handle_arch_irq);
}
asmlinkage void noinstr el0t_64_irq_handler(struct pt_regs *regs)
{
__el0_irq_handler_common(regs);
}
static void noinstr __el0_fiq_handler_common(struct pt_regs *regs)
{
el0_interrupt(regs, handle_arch_fiq);
}
asmlinkage void noinstr el0t_64_fiq_handler(struct pt_regs *regs)
{
__el0_fiq_handler_common(regs);
}
static void noinstr __el0_error_handler_common(struct pt_regs *regs)
{
unsigned long esr = read_sysreg(esr_el1);
enter_from_user_mode(regs);
local_daif_restore(DAIF_ERRCTX);
arm64_enter_nmi(regs);
do_serror(regs, esr);
arm64_exit_nmi(regs);
local_daif_restore(DAIF_PROCCTX);
exit_to_user_mode(regs);
}
asmlinkage void noinstr el0t_64_error_handler(struct pt_regs *regs)
{
__el0_error_handler_common(regs);
}
#ifdef CONFIG_COMPAT
static void noinstr el0_cp15(struct pt_regs *regs, unsigned long esr)
{
enter_from_user_mode(regs);
local_daif_restore(DAIF_PROCCTX);
do_cp15instr(esr, regs);
exit_to_user_mode(regs);
}
static void noinstr el0_svc_compat(struct pt_regs *regs)
{
enter_from_user_mode(regs);
cortex_a76_erratum_1463225_svc_handler();
do_el0_svc_compat(regs);
exit_to_user_mode(regs);
}
asmlinkage void noinstr el0t_32_sync_handler(struct pt_regs *regs)
{
unsigned long esr = read_sysreg(esr_el1);
switch (ESR_ELx_EC(esr)) {
case ESR_ELx_EC_SVC32:
el0_svc_compat(regs);
break;
case ESR_ELx_EC_DABT_LOW:
el0_da(regs, esr);
break;
case ESR_ELx_EC_IABT_LOW:
el0_ia(regs, esr);
break;
case ESR_ELx_EC_FP_ASIMD:
el0_fpsimd_acc(regs, esr);
break;
case ESR_ELx_EC_FP_EXC32:
el0_fpsimd_exc(regs, esr);
break;
case ESR_ELx_EC_PC_ALIGN:
el0_pc(regs, esr);
break;
case ESR_ELx_EC_UNKNOWN:
case ESR_ELx_EC_CP14_MR:
case ESR_ELx_EC_CP14_LS:
case ESR_ELx_EC_CP14_64:
el0_undef(regs, esr);
break;
case ESR_ELx_EC_CP15_32:
case ESR_ELx_EC_CP15_64:
el0_cp15(regs, esr);
break;
case ESR_ELx_EC_BREAKPT_LOW:
case ESR_ELx_EC_SOFTSTP_LOW:
case ESR_ELx_EC_WATCHPT_LOW:
case ESR_ELx_EC_BKPT32:
el0_dbg(regs, esr);
break;
default:
el0_inv(regs, esr);
}
}
asmlinkage void noinstr el0t_32_irq_handler(struct pt_regs *regs)
{
__el0_irq_handler_common(regs);
}
asmlinkage void noinstr el0t_32_fiq_handler(struct pt_regs *regs)
{
__el0_fiq_handler_common(regs);
}
asmlinkage void noinstr el0t_32_error_handler(struct pt_regs *regs)
{
__el0_error_handler_common(regs);
}
#else /* CONFIG_COMPAT */
UNHANDLED(el0t, 32, sync)
UNHANDLED(el0t, 32, irq)
UNHANDLED(el0t, 32, fiq)
UNHANDLED(el0t, 32, error)
#endif /* CONFIG_COMPAT */
#ifdef CONFIG_VMAP_STACK
asmlinkage void noinstr handle_bad_stack(struct pt_regs *regs)
{
unsigned long esr = read_sysreg(esr_el1);
unsigned long far = read_sysreg(far_el1);
arm64_enter_nmi(regs);
panic_bad_stack(regs, esr, far);
}
#endif /* CONFIG_VMAP_STACK */
#ifdef CONFIG_ARM_SDE_INTERFACE
asmlinkage noinstr unsigned long
__sdei_handler(struct pt_regs *regs, struct sdei_registered_event *arg)
{
unsigned long ret;
/*
* We didn't take an exception to get here, so the HW hasn't
* set/cleared bits in PSTATE that we may rely on.
*
* The original SDEI spec (ARM DEN 0054A) can be read ambiguously as to
* whether PSTATE bits are inherited unchanged or generated from
* scratch, and the TF-A implementation always clears PAN and always
* clears UAO. There are no other known implementations.
*
* Subsequent revisions (ARM DEN 0054B) follow the usual rules for how
* PSTATE is modified upon architectural exceptions, and so PAN is
* either inherited or set per SCTLR_ELx.SPAN, and UAO is always
* cleared.
*
* We must explicitly reset PAN to the expected state, including
* clearing it when the host isn't using it, in case a VM had it set.
*/
if (system_uses_hw_pan())
set_pstate_pan(1);
else if (cpu_has_pan())
set_pstate_pan(0);
arm64_enter_nmi(regs);
ret = do_sdei_event(regs, arg);
arm64_exit_nmi(regs);
return ret;
}
#endif /* CONFIG_ARM_SDE_INTERFACE */
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