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linux-yocto/arch/arm64/kernel/entry-common.c
Mark Rutland e500dff1e4 arm64/fpsimd: Do not discard modified SVE state 
[ Upstream commit 398edaa12f9cf2be7902f306fc023c20e3ebd3e4 ]

Historically SVE state was discarded deterministically early in the
syscall entry path, before ptrace is notified of syscall entry. This
permitted ptrace to modify SVE state before and after the "real" syscall
logic was executed, with the modified state being retained.

This behaviour was changed by commit:

  8c845e2731 ("arm64/sve: Leave SVE enabled on syscall if we don't context switch")

That commit was intended to speed up workloads that used SVE by
opportunistically leaving SVE enabled when returning from a syscall.
The syscall entry logic was modified to truncate the SVE state without
disabling userspace access to SVE, and fpsimd_save_user_state() was
modified to discard userspace SVE state whenever
in_syscall(current_pt_regs()) is true, i.e. when
current_pt_regs()->syscallno != NO_SYSCALL.

Leaving SVE enabled opportunistically resulted in a couple of changes to
userspace visible behaviour which weren't described at the time, but are
logical consequences of opportunistically leaving SVE enabled:

* Signal handlers can observe the type of saved state in the signal's
  sve_context record. When the kernel only tracks FPSIMD state, the 'vq'
  field is 0 and there is no space allocated for register contents. When
  the kernel tracks SVE state, the 'vq' field is non-zero and the
  register contents are saved into the record.

  As a result of the above commit, 'vq' (and the presence of SVE
  register state) is non-deterministically zero or non-zero for a period
  of time after a syscall. The effective register state is still
  deterministic.

  Hopefully no-one relies on this being deterministic. In general,
  handlers for asynchronous events cannot expect a deterministic state.

* Similarly to signal handlers, ptrace requests can observe the type of
  saved state in the NT_ARM_SVE and NT_ARM_SSVE regsets, as this is
  exposed in the header flags. As a result of the above commit, this is
  now in a non-deterministic state after a syscall. The effective
  register state is still deterministic.

  Hopefully no-one relies on this being deterministic. In general,
  debuggers would have to handle this changing at arbitrary points
  during program flow.

Discarding the SVE state within fpsimd_save_user_state() resulted in
other changes to userspace visible behaviour which are not desirable:

* A ptrace tracer can modify (or create) a tracee's SVE state at syscall
  entry or syscall exit. As a result of the above commit, the tracee's
  SVE state can be discarded non-deterministically after modification,
  rather than being retained as it previously was.

  Note that for co-operative tracer/tracee pairs, the tracer may
  (re)initialise the tracee's state arbitrarily after the tracee sends
  itself an initial SIGSTOP via a syscall, so this affects realistic
  design patterns.

* The current_pt_regs()->syscallno field can be modified via ptrace, and
  can be altered even when the tracee is not really in a syscall,
  causing non-deterministic discarding to occur in situations where this
  was not previously possible.

Further, using current_pt_regs()->syscallno in this way is unsound:

* There are data races between readers and writers of the
  current_pt_regs()->syscallno field.

  The current_pt_regs()->syscallno field is written in interruptible
  task context using plain C accesses, and is read in irq/softirq
  context using plain C accesses. These accesses are subject to data
  races, with the usual concerns with tearing, etc.

* Writes to current_pt_regs()->syscallno are subject to compiler
  reordering.

  As current_pt_regs()->syscallno is written with plain C accesses,
  the compiler is free to move those writes arbitrarily relative to
  anything which doesn't access the same memory location.

  In theory this could break signal return, where prior to restoring the
  SVE state, restore_sigframe() calls forget_syscall(). If the write
  were hoisted after restore of some SVE state, that state could be
  discarded unexpectedly.

  In practice that reordering cannot happen in the absence of LTO (as
  cross compilation-unit function calls happen prevent this reordering),
  and that reordering appears to be unlikely in the presence of LTO.

Additionally, since commit:

  f130ac0ae4 ("arm64: syscall: unmask DAIF earlier for SVCs")

... DAIF is unmasked before el0_svc_common() sets regs->syscallno to the
real syscall number. Consequently state may be saved in SVE format prior
to this point.

Considering all of the above, current_pt_regs()->syscallno should not be
used to infer whether the SVE state can be discarded. Luckily we can
instead use cpu_fp_state::to_save to track when it is safe to discard
the SVE state:

* At syscall entry, after the live SVE register state is truncated, set
  cpu_fp_state::to_save to FP_STATE_FPSIMD to indicate that only the
  FPSIMD portion is live and needs to be saved.

* At syscall exit, once the task's state is guaranteed to be live, set
  cpu_fp_state::to_save to FP_STATE_CURRENT to indicate that TIF_SVE
  must be considered to determine which state needs to be saved.

* Whenever state is modified, it must be saved+flushed prior to
  manipulation. The state will be truncated if necessary when it is
  saved, and reloading the state will set fp_state::to_save to
  FP_STATE_CURRENT, preventing subsequent discarding.

This permits SVE state to be discarded *only* when it is known to have
been truncated (and the non-FPSIMD portions must be zero), and ensures
that SVE state is retained after it is explicitly modified.

For backporting, note that this fix depends on the following commits:

* b2482807fb ("arm64/sme: Optimise SME exit on syscall entry")
* f130ac0ae4 ("arm64: syscall: unmask DAIF earlier for SVCs")
* 929fa99b1215 ("arm64/fpsimd: signal: Always save+flush state early")

Fixes: 8c845e2731 ("arm64/sve: Leave SVE enabled on syscall if we don't context switch")
Fixes: f130ac0ae4 ("arm64: syscall: unmask DAIF earlier for SVCs")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20250508132644.1395904-2-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-06-19 15:28:08 +02:00

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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,
* instrumentable 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,
* instrumentable 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,
* instrumentable 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,
* instrumentable 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 exit_to_user_mode_prepare(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);
lockdep_sys_exit();
}
static __always_inline void exit_to_user_mode(struct pt_regs *regs)
{
exit_to_user_mode_prepare(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, instrumentable 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, instrumentable 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, instrumentable 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, instrumentable 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 */
/*
* As per the ABI exit SME streaming mode and clear the SVE state not
* shared with FPSIMD on syscall entry.
*/
static inline void fpsimd_syscall_enter(void)
{
/* Ensure PSTATE.SM is clear, but leave PSTATE.ZA as-is. */
if (system_supports_sme())
sme_smstop_sm();
/*
* The CPU is not in streaming mode. If non-streaming SVE is not
* supported, there is no SVE state that needs to be discarded.
*/
if (!system_supports_sve())
return;
if (test_thread_flag(TIF_SVE)) {
unsigned int sve_vq_minus_one;
sve_vq_minus_one = sve_vq_from_vl(task_get_sve_vl(current)) - 1;
sve_flush_live(true, sve_vq_minus_one);
}
/*
* Any live non-FPSIMD SVE state has been zeroed. Allow
* fpsimd_save_user_state() to lazily discard SVE state until either
* the live state is unbound or fpsimd_syscall_exit() is called.
*/
__this_cpu_write(fpsimd_last_state.to_save, FP_STATE_FPSIMD);
}
static __always_inline void fpsimd_syscall_exit(void)
{
if (!system_supports_sve())
return;
/*
* The current task's user FPSIMD/SVE/SME state is now bound to this
* CPU. The fpsimd_last_state.to_save value is either:
*
* - FP_STATE_FPSIMD, if the state has not been reloaded on this CPU
* since fpsimd_syscall_enter().
*
* - FP_STATE_CURRENT, if the state has been reloaded on this CPU at
* any point.
*
* Reset this to FP_STATE_CURRENT to stop lazy discarding.
*/
__this_cpu_write(fpsimd_last_state.to_save, FP_STATE_CURRENT);
}
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_el1_undef(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_el0_sys(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_el0_undef(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_mops(struct pt_regs *regs, unsigned long esr)
{
enter_from_user_mode(regs);
local_daif_restore(DAIF_PROCCTX);
do_el0_mops(regs, esr);
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();
fpsimd_syscall_enter();
local_daif_restore(DAIF_PROCCTX);
do_el0_svc(regs);
exit_to_user_mode(regs);
fpsimd_syscall_exit();
}
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_MOPS:
el0_mops(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_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_el0_cp15(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();
local_daif_restore(DAIF_PROCCTX);
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 __noreturn 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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