Commit dbfbd87e authored by Mark Rutland's avatar Mark Rutland Committed by Will Deacon
Browse files

arm64: factor insn read out of call_undef_hook() 



Subsequent patches will rework EL0 UNDEF handling, removing the need for
struct undef_hook and call_undef_hook. In preparation for those changes,
this patch factors the logic for reading user instructions out of
call_undef_hook() and into a new user_insn_read() helper, matching the
style of the existing aarch64_insn_read() helper used for reading kernel
instructions.

There should be no functional change as a result of this patch.

Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20221019144123.612388-5-mark.rutland@arm.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent bff8f413

arch/arm64/kernel/traps.c

+22 −9
Original line number Diff line number Diff line
@@ -394,25 +394,22 @@ void unregister_undef_hook(struct undef_hook *hook) 
	raw_spin_unlock_irqrestore(&undef_lock, flags);

}



static int call_undef_hook(struct pt_regs *regs)

static int user_insn_read(struct pt_regs *regs, u32 *insnp)

{

	struct undef_hook *hook;

	unsigned long flags;

	u32 instr;

	int (*fn)(struct pt_regs *regs, u32 instr) = NULL;

	unsigned long pc = instruction_pointer(regs);



	if (compat_thumb_mode(regs)) {

		/* 16-bit Thumb instruction */

		__le16 instr_le;

		if (get_user(instr_le, (__le16 __user *)pc))

			goto exit;

			return -EFAULT;

		instr = le16_to_cpu(instr_le);

		if (aarch32_insn_is_wide(instr)) {

			u32 instr2;



			if (get_user(instr_le, (__le16 __user *)(pc + 2)))

				goto exit;

				return -EFAULT;

			instr2 = le16_to_cpu(instr_le);

			instr = (instr << 16) | instr2;

		}
@@ -420,10 +417,20 @@ static int call_undef_hook(struct pt_regs *regs) 
		/* 32-bit ARM instruction */

		__le32 instr_le;

		if (get_user(instr_le, (__le32 __user *)pc))

			goto exit;

			return -EFAULT;

		instr = le32_to_cpu(instr_le);

	}



	*insnp = instr;

	return 0;

}



static int call_undef_hook(struct pt_regs *regs, u32 instr)

{

	struct undef_hook *hook;

	unsigned long flags;

	int (*fn)(struct pt_regs *regs, u32 instr) = NULL;



	raw_spin_lock_irqsave(&undef_lock, flags);

	list_for_each_entry(hook, &undef_hook, node)

		if ((instr & hook->instr_mask) == hook->instr_val &&
@@ -431,7 +438,7 @@ static int call_undef_hook(struct pt_regs *regs) 
			fn = hook->fn;



	raw_spin_unlock_irqrestore(&undef_lock, flags);

exit:



	return fn ? fn(regs, instr) : 1;

}
@@ -483,13 +490,19 @@ void arm64_notify_segfault(unsigned long addr) 


void do_el0_undef(struct pt_regs *regs, unsigned long esr)

{

	u32 insn;



	/* check for AArch32 breakpoint instructions */

	if (!aarch32_break_handler(regs))

		return;



	if (call_undef_hook(regs) == 0)

	if (user_insn_read(regs, &insn))

		goto out_err;



	if (call_undef_hook(regs, insn) == 0)

		return;



out_err:

	force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0);

}