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Message-ID: <20191127151154.GC51937@lakrids.cambridge.arm.com>
Date: Wed, 27 Nov 2019 15:11:55 +0000
From: Mark Rutland <mark.rutland@....com>
To: Pavel Tatashin <pasha.tatashin@...een.com>
Cc: jmorris@...ei.org, sashal@...nel.org, linux-kernel@...r.kernel.org,
catalin.marinas@....com, will@...nel.org, steve.capper@....com,
linux-arm-kernel@...ts.infradead.org, marc.zyngier@....com,
james.morse@....com, vladimir.murzin@....com, tglx@...utronix.de,
gregkh@...uxfoundation.org, allison@...utok.net, info@...ux.net,
alexios.zavras@...el.com, sstabellini@...nel.org,
boris.ostrovsky@...cle.com, jgross@...e.com, stefan@...er.ch,
yamada.masahiro@...ionext.com, xen-devel@...ts.xenproject.org,
linux@...linux.org.uk
Subject: Re: [PATCH v2 3/3] arm64: remove the rest of asm-uaccess.h
On Thu, Nov 21, 2019 at 09:24:06PM -0500, Pavel Tatashin wrote:
> The __uaccess_ttbr0_disable and __uaccess_ttbr0_enable,
> are the last two macros defined in asm-uaccess.h.
>
> Replace them with C wrappers and call C functions from
> kernel_entry and kernel_exit.
For now, please leave those as-is.
I don't think we want to have out-of-line C wrappers in the middle of
the entry assembly where we don't have a complete kernel environment.
The use in entry code can also assume non-preemptibility, while the C
functions have to explcitily disable that.
We can certainly remove the includes of <asm/asm-uaccess.h> elsewhere,
and maybe fold the macros into entry.S if it's not too crowded.
Thanks,
Mark.
>
> Signed-off-by: Pavel Tatashin <pasha.tatashin@...een.com>
> ---
> arch/arm64/include/asm/asm-uaccess.h | 38 ----------------------------
> arch/arm64/kernel/entry.S | 6 ++---
> arch/arm64/lib/clear_user.S | 2 +-
> arch/arm64/lib/copy_from_user.S | 2 +-
> arch/arm64/lib/copy_in_user.S | 2 +-
> arch/arm64/lib/copy_to_user.S | 2 +-
> arch/arm64/mm/cache.S | 1 -
> arch/arm64/mm/context.c | 12 +++++++++
> 8 files changed, 19 insertions(+), 46 deletions(-)
> delete mode 100644 arch/arm64/include/asm/asm-uaccess.h
>
> diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h
> deleted file mode 100644
> index 8f763e5b41b1..000000000000
> --- a/arch/arm64/include/asm/asm-uaccess.h
> +++ /dev/null
> @@ -1,38 +0,0 @@
> -/* SPDX-License-Identifier: GPL-2.0 */
> -#ifndef __ASM_ASM_UACCESS_H
> -#define __ASM_ASM_UACCESS_H
> -
> -#include <asm/alternative.h>
> -#include <asm/kernel-pgtable.h>
> -#include <asm/mmu.h>
> -#include <asm/sysreg.h>
> -#include <asm/assembler.h>
> -
> -/*
> - * User access enabling/disabling macros.
> - */
> -#ifdef CONFIG_ARM64_SW_TTBR0_PAN
> - .macro __uaccess_ttbr0_disable, tmp1
> - mrs \tmp1, ttbr1_el1 // swapper_pg_dir
> - bic \tmp1, \tmp1, #TTBR_ASID_MASK
> - sub \tmp1, \tmp1, #RESERVED_TTBR0_SIZE // reserved_ttbr0 just before swapper_pg_dir
> - msr ttbr0_el1, \tmp1 // set reserved TTBR0_EL1
> - isb
> - add \tmp1, \tmp1, #RESERVED_TTBR0_SIZE
> - msr ttbr1_el1, \tmp1 // set reserved ASID
> - isb
> - .endm
> -
> - .macro __uaccess_ttbr0_enable, tmp1, tmp2
> - get_current_task \tmp1
> - ldr \tmp1, [\tmp1, #TSK_TI_TTBR0] // load saved TTBR0_EL1
> - mrs \tmp2, ttbr1_el1
> - extr \tmp2, \tmp2, \tmp1, #48
> - ror \tmp2, \tmp2, #16
> - msr ttbr1_el1, \tmp2 // set the active ASID
> - isb
> - msr ttbr0_el1, \tmp1 // set the non-PAN TTBR0_EL1
> - isb
> - .endm
> -#endif
> -#endif
> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> index 583f71abbe98..c7b571e6d0f2 100644
> --- a/arch/arm64/kernel/entry.S
> +++ b/arch/arm64/kernel/entry.S
> @@ -22,8 +22,8 @@
> #include <asm/mmu.h>
> #include <asm/processor.h>
> #include <asm/ptrace.h>
> +#include <asm/kernel-pgtable.h>
> #include <asm/thread_info.h>
> -#include <asm/asm-uaccess.h>
> #include <asm/unistd.h>
>
> /*
> @@ -219,7 +219,7 @@ alternative_else_nop_endif
> and x23, x23, #~PSR_PAN_BIT // Clear the emulated PAN in the saved SPSR
> .endif
>
> - __uaccess_ttbr0_disable x21
> + bl __uaccess_ttbr0_disable_c
> 1:
> #endif
>
> @@ -293,7 +293,7 @@ alternative_else_nop_endif
> tbnz x22, #22, 1f // Skip re-enabling TTBR0 access if the PSR_PAN_BIT is set
> .endif
>
> - __uaccess_ttbr0_enable x0, x1
> + bl __uaccess_ttbr0_enable_c
>
> .if \el == 0
> /*
> diff --git a/arch/arm64/lib/clear_user.S b/arch/arm64/lib/clear_user.S
> index aeafc03e961a..b0b4a86a09e2 100644
> --- a/arch/arm64/lib/clear_user.S
> +++ b/arch/arm64/lib/clear_user.S
> @@ -6,7 +6,7 @@
> */
> #include <linux/linkage.h>
>
> -#include <asm/asm-uaccess.h>
> +#include <asm/alternative.h>
> #include <asm/assembler.h>
>
> .text
> diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S
> index ebb3c06cbb5d..142bc7505518 100644
> --- a/arch/arm64/lib/copy_from_user.S
> +++ b/arch/arm64/lib/copy_from_user.S
> @@ -5,7 +5,7 @@
>
> #include <linux/linkage.h>
>
> -#include <asm/asm-uaccess.h>
> +#include <asm/alternative.h>
> #include <asm/assembler.h>
> #include <asm/cache.h>
>
> diff --git a/arch/arm64/lib/copy_in_user.S b/arch/arm64/lib/copy_in_user.S
> index 3d8153a1ebce..04dc48ca26f7 100644
> --- a/arch/arm64/lib/copy_in_user.S
> +++ b/arch/arm64/lib/copy_in_user.S
> @@ -7,7 +7,7 @@
>
> #include <linux/linkage.h>
>
> -#include <asm/asm-uaccess.h>
> +#include <asm/alternative.h>
> #include <asm/assembler.h>
> #include <asm/cache.h>
>
> diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S
> index 357eae2c18eb..8f3218ae88ab 100644
> --- a/arch/arm64/lib/copy_to_user.S
> +++ b/arch/arm64/lib/copy_to_user.S
> @@ -5,7 +5,7 @@
>
> #include <linux/linkage.h>
>
> -#include <asm/asm-uaccess.h>
> +#include <asm/alternative.h>
> #include <asm/assembler.h>
> #include <asm/cache.h>
>
> diff --git a/arch/arm64/mm/cache.S b/arch/arm64/mm/cache.S
> index 408d317a47d2..7940d6ef5da5 100644
> --- a/arch/arm64/mm/cache.S
> +++ b/arch/arm64/mm/cache.S
> @@ -12,7 +12,6 @@
> #include <asm/assembler.h>
> #include <asm/cpufeature.h>
> #include <asm/alternative.h>
> -#include <asm/asm-uaccess.h>
>
> /*
> * __arch_flush_icache_range(start,end)
> diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
> index b5e329fde2dd..4fc32c504dea 100644
> --- a/arch/arm64/mm/context.c
> +++ b/arch/arm64/mm/context.c
> @@ -237,6 +237,18 @@ void check_and_switch_context(struct mm_struct *mm, unsigned int cpu)
> cpu_switch_mm(mm->pgd, mm);
> }
>
> +#ifdef CONFIG_ARM64_SW_TTBR0_PAN
> +asmlinkage void __uaccess_ttbr0_enable_c(void)
> +{
> + __uaccess_ttbr0_enable();
> +}
> +
> +asmlinkage void __uaccess_ttbr0_disable_c(void)
> +{
> + __uaccess_ttbr0_disable();
> +}
> +#endif
> +
> /* Errata workaround post TTBRx_EL1 update. */
> asmlinkage void post_ttbr_update_workaround(void)
> {
> --
> 2.24.0
>
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