On 5/3/24 18:31, Joey Gouly wrote:
> Add PKEY support to signals, by saving and restoring POR_EL0 from the
> stackframe.
>
> Signed-off-by: Joey Gouly <joey.go...@arm.com>
> Cc: Catalin Marinas <catalin.mari...@arm.com>
> Cc: Will Deacon <w...@kernel.org>
> Reviewed-by: Mark Brown <broo...@kernel.org>
> Acked-by: Szabolcs Nagy <szabolcs.n...@arm.com>
Reviewed-by: Anshuman Khandual <anshuman.khand...@arm.com>
> ---
> arch/arm64/include/uapi/asm/sigcontext.h | 7 ++++
> arch/arm64/kernel/signal.c | 52 ++++++++++++++++++++++++
> 2 files changed, 59 insertions(+)
>
> diff --git a/arch/arm64/include/uapi/asm/sigcontext.h
> b/arch/arm64/include/uapi/asm/sigcontext.h
> index 8a45b7a411e0..e4cba8a6c9a2 100644
> --- a/arch/arm64/include/uapi/asm/sigcontext.h
> +++ b/arch/arm64/include/uapi/asm/sigcontext.h
> @@ -98,6 +98,13 @@ struct esr_context {
> __u64 esr;
> };
>
> +#define POE_MAGIC 0x504f4530
> +
> +struct poe_context {
> + struct _aarch64_ctx head;
> + __u64 por_el0;
> +};
> +
> /*
> * extra_context: describes extra space in the signal frame for
> * additional structures that don't fit in sigcontext.__reserved[].
> diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
> index 4a77f4976e11..077436a8bc10 100644
> --- a/arch/arm64/kernel/signal.c
> +++ b/arch/arm64/kernel/signal.c
> @@ -63,6 +63,7 @@ struct rt_sigframe_user_layout {
> unsigned long fpmr_offset;
> unsigned long extra_offset;
> unsigned long end_offset;
> + unsigned long poe_offset;
> };
>
> #define BASE_SIGFRAME_SIZE round_up(sizeof(struct rt_sigframe), 16)
> @@ -185,6 +186,8 @@ struct user_ctxs {
> u32 zt_size;
> struct fpmr_context __user *fpmr;
> u32 fpmr_size;
> + struct poe_context __user *poe;
> + u32 poe_size;
> };
>
> static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
> @@ -258,6 +261,21 @@ static int restore_fpmr_context(struct user_ctxs *user)
> return err;
> }
>
> +static int restore_poe_context(struct user_ctxs *user)
> +{
> + u64 por_el0;
> + int err = 0;
> +
> + if (user->poe_size != sizeof(*user->poe))
> + return -EINVAL;
> +
> + __get_user_error(por_el0, &(user->poe->por_el0), err);
> + if (!err)
> + write_sysreg_s(por_el0, SYS_POR_EL0);
> +
> + return err;
> +}
> +
> #ifdef CONFIG_ARM64_SVE
>
> static int preserve_sve_context(struct sve_context __user *ctx)
> @@ -621,6 +639,7 @@ static int parse_user_sigframe(struct user_ctxs *user,
> user->za = NULL;
> user->zt = NULL;
> user->fpmr = NULL;
> + user->poe = NULL;
>
> if (!IS_ALIGNED((unsigned long)base, 16))
> goto invalid;
> @@ -671,6 +690,17 @@ static int parse_user_sigframe(struct user_ctxs *user,
> /* ignore */
> break;
>
> + case POE_MAGIC:
> + if (!system_supports_poe())
> + goto invalid;
> +
> + if (user->poe)
> + goto invalid;
> +
> + user->poe = (struct poe_context __user *)head;
> + user->poe_size = size;
> + break;
> +
> case SVE_MAGIC:
> if (!system_supports_sve() && !system_supports_sme())
> goto invalid;
> @@ -857,6 +887,9 @@ static int restore_sigframe(struct pt_regs *regs,
> if (err == 0 && system_supports_sme2() && user.zt)
> err = restore_zt_context(&user);
>
> + if (err == 0 && system_supports_poe() && user.poe)
> + err = restore_poe_context(&user);
> +
> return err;
> }
>
> @@ -980,6 +1013,13 @@ static int setup_sigframe_layout(struct
> rt_sigframe_user_layout *user,
> return err;
> }
>
> + if (system_supports_poe()) {
> + err = sigframe_alloc(user, &user->poe_offset,
> + sizeof(struct poe_context));
> + if (err)
> + return err;
> + }
> +
> return sigframe_alloc_end(user);
> }
>
> @@ -1020,6 +1060,15 @@ static int setup_sigframe(struct
> rt_sigframe_user_layout *user,
> __put_user_error(current->thread.fault_code, &esr_ctx->esr,
> err);
> }
>
> + if (system_supports_poe() && err == 0 && user->poe_offset) {
> + struct poe_context __user *poe_ctx =
> + apply_user_offset(user, user->poe_offset);
> +
> + __put_user_error(POE_MAGIC, &poe_ctx->head.magic, err);
> + __put_user_error(sizeof(*poe_ctx), &poe_ctx->head.size, err);
> + __put_user_error(read_sysreg_s(SYS_POR_EL0), &poe_ctx->por_el0,
> err);
> + }
> +
> /* Scalable Vector Extension state (including streaming), if present */
> if ((system_supports_sve() || system_supports_sme()) &&
> err == 0 && user->sve_offset) {
> @@ -1178,6 +1227,9 @@ static void setup_return(struct pt_regs *regs, struct
> k_sigaction *ka,
> sme_smstop();
> }
>
> + if (system_supports_poe())
> + write_sysreg_s(POR_EL0_INIT, SYS_POR_EL0);
> +
> if (ka->sa.sa_flags & SA_RESTORER)
> sigtramp = ka->sa.sa_restorer;
> else
