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arm64: Trap WFI executed in userspace

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It recently came to light that userspace can execute WFI, and that
the arm64 kernel doesn't trap this event. This sounds rather benign,
but the kernel should decide when it wants to wait for an interrupt,
and not userspace.

Let's trap WFI and immediately return after having skipped the
instruction. This effectively makes WFI a rather expensive NOP.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Marc Zyngier
2018-10-01 12:19:43 +01:00
committed by Catalin Marinas
parent ee91176120
commit c219bc4e92
4 changed files with 19 additions and 2 deletions
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5
arch/arm64/include/asm/esr.h
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@@ -137,6 +137,8 @@
#define ESR_ELx_CV (UL(1) << 24)
#define ESR_ELx_COND_SHIFT (20)
#define ESR_ELx_COND_MASK (UL(0xF) << ESR_ELx_COND_SHIFT)
#define ESR_ELx_WFx_ISS_TI (UL(1) << 0)
#define ESR_ELx_WFx_ISS_WFI (UL(0) << 0)
#define ESR_ELx_WFx_ISS_WFE (UL(1) << 0)
#define ESR_ELx_xVC_IMM_MASK ((1UL << 16) - 1)
@@ -148,6 +150,9 @@
#define DISR_EL1_ESR_MASK (ESR_ELx_AET | ESR_ELx_EA | ESR_ELx_FSC)
/* ESR value templates for specific events */
#define ESR_ELx_WFx_MASK (ESR_ELx_EC_MASK | ESR_ELx_WFx_ISS_TI)
#define ESR_ELx_WFx_WFI_VAL ((ESR_ELx_EC_WFx << ESR_ELx_EC_SHIFT) | \
ESR_ELx_WFx_ISS_WFI)
/* BRK instruction trap from AArch64 state */
#define ESR_ELx_VAL_BRK64(imm) \