Re: [PATCH v7 08/11] arm64: traps: Shuffle code to eliminate forward declarations

Kees Cook
2020-02-26T21:39:56Z

On Wed, Feb 26, 2020 at 03:57:11PM +0000, Mark Brown wrote:
> From: Dave Martin <Dave.Martin@arm.com>
>
> Hoist the IT state handling code earlier in traps.c, to avoid
> accumulating forward declarations.
>
> No functional change.
>
> Signed-off-by: Dave Martin <Dave.Martin@arm.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
> arch/arm64/kernel/traps.c | 103 ++++++++++++++++++--------------------
> 1 file changed, 50 insertions(+), 53 deletions(-)
>
> diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> index bc9f4292bfc3..3c07a7074145 100644
> --- a/arch/arm64/kernel/traps.c
> +++ b/arch/arm64/kernel/traps.c
> @@ -272,7 +272,55 @@ void arm64_notify_die(const char *str, struct pt_regs *regs,
> }
> }
>
> -static void advance_itstate(struct pt_regs *regs);
> +#ifdef CONFIG_COMPAT
> +#define PSTATE_IT_1_0_SHIFT 25
> +#define PSTATE_IT_1_0_MASK (0x3 << PSTATE_IT_1_0_SHIFT)
> +#define PSTATE_IT_7_2_SHIFT 10
> +#define PSTATE_IT_7_2_MASK (0x3f << PSTATE_IT_7_2_SHIFT)
> +
> +static u32 compat_get_it_state(struct pt_regs *regs)
> +{
> + u32 it, pstate = regs->pstate;
> +
> + it = (pstate & PSTATE_IT_1_0_MASK) >> PSTATE_IT_1_0_SHIFT;
> + it |= ((pstate & PSTATE_IT_7_2_MASK) >> PSTATE_IT_7_2_SHIFT) << 2;
> +
> + return it;
> +}
> +
> +static void compat_set_it_state(struct pt_regs *regs, u32 it)
> +{
> + u32 pstate_it;
> +
> + pstate_it = (it << PSTATE_IT_1_0_SHIFT) & PSTATE_IT_1_0_MASK;
> + pstate_it |= ((it >> 2) << PSTATE_IT_7_2_SHIFT) & PSTATE_IT_7_2_MASK;
> +
> + regs->pstate &= ~PSR_AA32_IT_MASK;
> + regs->pstate |= pstate_it;
> +}
> +
> +static void advance_itstate(struct pt_regs *regs)
> +{
> + u32 it;
> +
> + /* ARM mode */
> + if (!(regs->pstate & PSR_AA32_T_BIT) ||
> + !(regs->pstate & PSR_AA32_IT_MASK))
> + return;
> +
> + it = compat_get_it_state(regs);
> +
> + /*
> + * If this is the last instruction of the block, wipe the IT
> + * state. Otherwise advance it.
> + */
> + if (!(it & 7))
> + it = 0;
> + else
> + it = (it & 0xe0) | ((it << 1) & 0x1f);
> +
> + compat_set_it_state(regs, it);
> +}
>
> void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
> {
> @@ -285,7 +333,7 @@ void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
> if (user_mode(regs))
> user_fastforward_single_step(current);
>
> - if (regs->pstate & PSR_MODE32_BIT)
> + if (compat_user_mode(regs))
> advance_itstate(regs);
> }
>
> @@ -578,34 +626,6 @@ static const struct sys64_hook sys64_hooks[] = {
> {},
> };
>
> -
> -#ifdef CONFIG_COMPAT
> -#define PSTATE_IT_1_0_SHIFT 25
> -#define PSTATE_IT_1_0_MASK (0x3 << PSTATE_IT_1_0_SHIFT)
> -#define PSTATE_IT_7_2_SHIFT 10
> -#define PSTATE_IT_7_2_MASK (0x3f << PSTATE_IT_7_2_SHIFT)
> -
> -static u32 compat_get_it_state(struct pt_regs *regs)
> -{
> - u32 it, pstate = regs->pstate;
> -
> - it = (pstate & PSTATE_IT_1_0_MASK) >> PSTATE_IT_1_0_SHIFT;
> - it |= ((pstate & PSTATE_IT_7_2_MASK) >> PSTATE_IT_7_2_SHIFT) << 2;
> -
> - return it;
> -}
> -
> -static void compat_set_it_state(struct pt_regs *regs, u32 it)
> -{
> - u32 pstate_it;
> -
> - pstate_it = (it << PSTATE_IT_1_0_SHIFT) & PSTATE_IT_1_0_MASK;
> - pstate_it |= ((it >> 2) << PSTATE_IT_7_2_SHIFT) & PSTATE_IT_7_2_MASK;
> -
> - regs->pstate &= ~PSR_AA32_IT_MASK;
> - regs->pstate |= pstate_it;
> -}
> -
> static bool cp15_cond_valid(unsigned int esr, struct pt_regs *regs)
> {
> int cond;
> @@ -626,29 +646,6 @@ static bool cp15_cond_valid(unsigned int esr, struct pt_regs *regs)
> return aarch32_opcode_cond_checks[cond](regs->pstate);
> }
>
> -static void advance_itstate(struct pt_regs *regs)
> -{
> - u32 it;
> -
> - /* ARM mode */
> - if (!(regs->pstate & PSR_AA32_T_BIT) ||
> - !(regs->pstate & PSR_AA32_IT_MASK))
> - return;
> -
> - it = compat_get_it_state(regs);
> -
> - /*
> - * If this is the last instruction of the block, wipe the IT
> - * state. Otherwise advance it.
> - */
> - if (!(it & 7))
> - it = 0;
> - else
> - it = (it & 0xe0) | ((it << 1) & 0x1f);
> -
> - compat_set_it_state(regs, it);
> -}
> -
> static void compat_cntfrq_read_handler(unsigned int esr, struct pt_regs *regs)
> {
> int reg = (esr & ESR_ELx_CP15_32_ISS_RT_MASK) >> ESR_ELx_CP15_32_ISS_RT_SHIFT;
> --
> 2.20.1
>

--
Kees Cook