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arm64: entry: move el1 irq/nmi logic to C

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In preparation for reworking the EL1 irq/nmi entry code, move the
existing logic to C. We no longer need the asm_nmi_enter() and
asm_nmi_exit() wrappers, so these are removed. The new C functions are
marked noinstr, which prevents compiler instrumentation and runtime
probing.

In subsequent patches we'll want the new C helpers to be called in all
cases, so we don't bother wrapping the calls with ifdeferry. Even when
the new C functions are stubs the trivial calls are unlikely to have a
measurable impact on the IRQ or NMI paths anyway.

Prototypes are added to <asm/exception.h> as otherwise (in some
configurations) GCC will complain about the lack of a forward
declaration. We already do this for existing function, e.g.
enter_from_user_mode().

The new helpers are marked as noinstr (which prevents all
instrumentation, tracing, and kprobes). Otherwise, there should be no
functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201130115950.22492-7-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Mark Rutland 2020-11-30 11:59:45 +00:00 committed by Will Deacon
parent 3cb5ed4d76
commit 105fc33520
4 changed files with 22 additions and 45 deletions
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2
arch/arm64/include/asm/exception.h
View file

@ -31,6 +31,8 @@ static inline u32 disr_to_esr(u64 disr)
return esr;
}
asmlinkage void noinstr enter_el1_irq_or_nmi(struct pt_regs *regs);
asmlinkage void noinstr exit_el1_irq_or_nmi(struct pt_regs *regs);
asmlinkage void enter_from_user_mode(void);
void do_mem_abort(unsigned long addr, unsigned int esr, struct pt_regs *regs);
void do_undefinstr(struct pt_regs *regs);

16
arch/arm64/kernel/entry-common.c
View file

@ -17,6 +17,22 @@
#include <asm/mmu.h>
#include <asm/sysreg.h>
asmlinkage void noinstr enter_el1_irq_or_nmi(struct pt_regs *regs)
{
if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
nmi_enter();
trace_hardirqs_off();
}
asmlinkage void noinstr exit_el1_irq_or_nmi(struct pt_regs *regs)
{
if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
nmi_exit();
else
trace_hardirqs_on();
}
static void noinstr el1_abort(struct pt_regs *regs, unsigned long esr)
{
unsigned long far = read_sysreg(far_el1);

34
arch/arm64/kernel/entry.S
View file

@ -637,16 +637,8 @@ SYM_CODE_START_LOCAL_NOALIGN(el1_irq)
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
mov x0, sp
bl enter_el1_irq_or_nmi
irq_handler
@ -665,26 +657,8 @@ alternative_else_nop_endif
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
mov x0, sp
bl exit_el1_irq_or_nmi
kernel_exit 1
SYM_CODE_END(el1_irq)

15
arch/arm64/kernel/irq.c
View file

@ -67,18 +67,3 @@ void __init init_IRQ(void)
local_daif_restore(DAIF_PROCCTX_NOIRQ);
}
}
/*
* Stubs to make nmi_enter/exit() code callable from ASM
*/
asmlinkage void notrace asm_nmi_enter(void)
{
nmi_enter();
}
NOKPROBE_SYMBOL(asm_nmi_enter);
asmlinkage void notrace asm_nmi_exit(void)
{
nmi_exit();
}
NOKPROBE_SYMBOL(asm_nmi_exit);