4.19-stable review patch. If anyone has any objections, please let me know.
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From: Will Deacon will.deacon@arm.com
[ Upstream commit 0bf0f444b2c49241b2b39aa3cf210d7c95ef6c34 ]
Rather than panic() when taking an undefined instruction exception from EL1, allow a hook to be registered in case we want to emulate the instruction, like we will for the SSBS PSTATE manipulation instructions.
Signed-off-by: Will Deacon will.deacon@arm.com Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/kernel/entry.S | 2 +- arch/arm64/kernel/traps.c | 11 +++++++---- 2 files changed, 8 insertions(+), 5 deletions(-)
--- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -589,7 +589,7 @@ el1_undef: inherit_daif pstate=x23, tmp=x2 mov x0, sp bl do_undefinstr - ASM_BUG() + kernel_exit 1 el1_dbg: /* * Debug exception handling --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -310,10 +310,12 @@ static int call_undef_hook(struct pt_reg int (*fn)(struct pt_regs *regs, u32 instr) = NULL; void __user *pc = (void __user *)instruction_pointer(regs);
- if (!user_mode(regs)) - return 1; - - if (compat_thumb_mode(regs)) { + if (!user_mode(regs)) { + __le32 instr_le; + if (probe_kernel_address((__force __le32 *)pc, instr_le)) + goto exit; + instr = le32_to_cpu(instr_le); + } else if (compat_thumb_mode(regs)) { /* 16-bit Thumb instruction */ __le16 instr_le; if (get_user(instr_le, (__le16 __user *)pc)) @@ -407,6 +409,7 @@ asmlinkage void __exception do_undefinst return;
force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc); + BUG_ON(!user_mode(regs)); }
void cpu_enable_cache_maint_trap(const struct arm64_cpu_capabilities *__unused)