Re: [PATCH v3 15/25] arm64: add POE signal support

[Szabolcs Nagy <szabolcs.nagy@arm.com>]

The 12/11/2023 18:53, Catalin Marinas wrote:
> + Szabolcs for libc ack (and keeping the full patch quoted below)
> 
> You should cc Szabolcs when reposting, we need his ack on the UAPI
> changes.
> 
> On Fri, Nov 24, 2023 at 04:35:00PM +0000, Joey Gouly wrote:
> > Add PKEY support to signals, by saving and restoring POR_EL0 from the stackframe.

this looks good.

Acked-by: Szabolcs Nagy <szabolcs.nagy@arm.com>

> > 
> > Signed-off-by: Joey Gouly <joey.gouly@arm.com>
> > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > Cc: Will Deacon <will@kernel.org>
> > Reviewed-by: Mark Brown <broonie@kernel.org>
> > ---
> >  arch/arm64/include/uapi/asm/sigcontext.h |  7 ++++
> >  arch/arm64/kernel/signal.c               | 51 ++++++++++++++++++++++++
> >  2 files changed, 58 insertions(+)
> > 
> > diff --git a/arch/arm64/include/uapi/asm/sigcontext.h b/arch/arm64/include/uapi/asm/sigcontext.h
> > index f23c1dc3f002..cef85eeaf541 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 0e8beb3349ea..379f364005bf 100644
> > --- a/arch/arm64/kernel/signal.c
> > +++ b/arch/arm64/kernel/signal.c
> > @@ -62,6 +62,7 @@ struct rt_sigframe_user_layout {
> >  	unsigned long zt_offset;
> >  	unsigned long extra_offset;
> >  	unsigned long end_offset;
> > +	unsigned long poe_offset;
> >  };
> >  
> >  #define BASE_SIGFRAME_SIZE round_up(sizeof(struct rt_sigframe), 16)
> > @@ -182,6 +183,8 @@ struct user_ctxs {
> >  	u32 za_size;
> >  	struct zt_context __user *zt;
> >  	u32 zt_size;
> > +	struct poe_context __user *poe;
> > +	u32 poe_size;
> >  };
> >  
> >  static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
> > @@ -227,6 +230,20 @@ static int restore_fpsimd_context(struct user_ctxs *user)
> >  	return err ? -EFAULT : 0;
> >  }
> >  
> > +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
> >  
> > @@ -590,6 +607,7 @@ static int parse_user_sigframe(struct user_ctxs *user,
> >  	user->tpidr2 = NULL;
> >  	user->za = NULL;
> >  	user->zt = NULL;
> > +	user->poe = NULL;
> >  
> >  	if (!IS_ALIGNED((unsigned long)base, 16))
> >  		goto invalid;
> > @@ -640,6 +658,17 @@ 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;
> > @@ -812,6 +841,9 @@ 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;
> >  }
> >  
> > @@ -928,6 +960,13 @@ static int setup_sigframe_layout(struct rt_sigframe_user_layout *user,
> >  		}
> >  	}
> >  
> > +	if (system_supports_poe()) {
> > +		err = sigframe_alloc(user, &user->poe_offset,
> > +				     sizeof(struct poe_context));
> > +		if (err)
> > +			return err;
> > +	}
> > +
> >  	return sigframe_alloc_end(user);
> >  }
> >  
> > @@ -968,6 +1007,15 @@ 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) {
> > @@ -1119,6 +1167,9 @@ 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
> > -- 
> > 2.25.1

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