From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 13/18] arm64: entry: Hook up entry trampoline to exception vectors
Date: Fri, 1 Dec 2017 17:40:03 +0000 [thread overview]
Message-ID: <20171201174002.GA8826@arm.com> (raw)
In-Reply-To: <20171201135300.novwsr5yxveeeq7m@lakrids.cambridge.arm.com>
On Fri, Dec 01, 2017 at 01:53:01PM +0000, Mark Rutland wrote:
> On Thu, Nov 30, 2017 at 04:39:41PM +0000, Will Deacon wrote:
> > .macro kernel_ventry, el, label, regsize = 64
> > .align 7
> > +#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
> > + .if \el == 0
> > + .if \regsize == 64
> > + mrs x30, tpidrro_el0
> > + msr tpidrro_el0, xzr
> > + .else
> > + mov x30, xzr
>
> I guess that's just to prevent acccidental leaks if we dump registers
> somewhere, since we used x30 as a scratch register?
Indeed. I don't have a concrete example, but I was worried about things
like perf and ptrace, which might allow you to get at the AArch64 register
state for a compat task so it felt like a good idea to zero this.
Will
WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will.deacon@arm.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, catalin.marinas@arm.com,
ard.biesheuvel@linaro.org, sboyd@codeaurora.org,
dave.hansen@linux.intel.com, keescook@chromium.org,
msalter@redhat.com, labbott@redhat.com, tglx@linutronix.de
Subject: Re: [PATCH v2 13/18] arm64: entry: Hook up entry trampoline to exception vectors
Date: Fri, 1 Dec 2017 17:40:03 +0000 [thread overview]
Message-ID: <20171201174002.GA8826@arm.com> (raw)
In-Reply-To: <20171201135300.novwsr5yxveeeq7m@lakrids.cambridge.arm.com>
On Fri, Dec 01, 2017 at 01:53:01PM +0000, Mark Rutland wrote:
> On Thu, Nov 30, 2017 at 04:39:41PM +0000, Will Deacon wrote:
> > .macro kernel_ventry, el, label, regsize = 64
> > .align 7
> > +#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
> > + .if \el == 0
> > + .if \regsize == 64
> > + mrs x30, tpidrro_el0
> > + msr tpidrro_el0, xzr
> > + .else
> > + mov x30, xzr
>
> I guess that's just to prevent acccidental leaks if we dump registers
> somewhere, since we used x30 as a scratch register?
Indeed. I don't have a concrete example, but I was worried about things
like perf and ptrace, which might allow you to get at the AArch64 register
state for a compat task so it felt like a good idea to zero this.
Will
next prev parent reply other threads:[~2017-12-01 17:40 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-30 16:39 [PATCH v2 00/18] arm64: Unmap the kernel whilst running in userspace (KAISER) Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-11-30 16:39 ` [PATCH v2 01/18] arm64: mm: Use non-global mappings for kernel space Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-11-30 16:39 ` [PATCH v2 02/18] arm64: mm: Temporarily disable ARM64_SW_TTBR0_PAN Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-11-30 16:39 ` [PATCH v2 03/18] arm64: mm: Move ASID from TTBR0 to TTBR1 Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-11-30 17:36 ` Mark Rutland
2017-11-30 17:36 ` Mark Rutland
2017-11-30 16:39 ` [PATCH v2 04/18] arm64: mm: Remove pre_ttbr0_update_workaround for Falkor erratum #E1003 Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-11-30 16:39 ` [PATCH v2 05/18] arm64: mm: Rename post_ttbr0_update_workaround Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-11-30 16:39 ` [PATCH v2 06/18] arm64: mm: Fix and re-enable ARM64_SW_TTBR0_PAN Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-12-01 11:48 ` Mark Rutland
2017-12-01 11:48 ` Mark Rutland
2017-11-30 16:39 ` [PATCH v2 07/18] arm64: mm: Allocate ASIDs in pairs Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-11-30 16:39 ` [PATCH v2 08/18] arm64: mm: Add arm64_kernel_unmapped_at_el0 helper Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-11-30 16:39 ` [PATCH v2 09/18] arm64: mm: Invalidate both kernel and user ASIDs when performing TLBI Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-11-30 16:39 ` [PATCH v2 10/18] arm64: entry: Add exception trampoline page for exceptions from EL0 Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-12-01 13:31 ` Mark Rutland
2017-12-01 13:31 ` Mark Rutland
2017-12-06 10:25 ` Ard Biesheuvel
2017-12-06 10:25 ` Ard Biesheuvel
2017-11-30 16:39 ` [PATCH v2 11/18] arm64: mm: Map entry trampoline into trampoline and kernel page tables Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-11-30 18:29 ` Mark Rutland
2017-11-30 18:29 ` Mark Rutland
2017-11-30 16:39 ` [PATCH v2 12/18] arm64: entry: Explicitly pass exception level to kernel_ventry macro Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-12-01 11:58 ` Mark Rutland
2017-12-01 11:58 ` Mark Rutland
2017-12-01 17:51 ` Will Deacon
2017-12-01 17:51 ` Will Deacon
2017-12-01 18:00 ` Mark Rutland
2017-12-01 18:00 ` Mark Rutland
2017-11-30 16:39 ` [PATCH v2 13/18] arm64: entry: Hook up entry trampoline to exception vectors Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-12-01 13:53 ` Mark Rutland
2017-12-01 13:53 ` Mark Rutland
2017-12-01 17:40 ` Will Deacon [this message]
2017-12-01 17:40 ` Will Deacon
2017-11-30 16:39 ` [PATCH v2 14/18] arm64: erratum: Work around Falkor erratum #E1003 in trampoline code Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-11-30 17:06 ` Robin Murphy
2017-11-30 17:06 ` Robin Murphy
2017-11-30 17:19 ` Will Deacon
2017-11-30 17:19 ` Will Deacon
2017-11-30 16:39 ` [PATCH v2 15/18] arm64: tls: Avoid unconditional zeroing of tpidrro_el0 for native tasks Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-11-30 16:39 ` [PATCH v2 16/18] arm64: entry: Add fake CPU feature for unmapping the kernel at EL0 Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-12-01 13:55 ` Mark Rutland
2017-12-01 13:55 ` Mark Rutland
2017-11-30 16:39 ` [PATCH v2 17/18] arm64: Kconfig: Add CONFIG_UNMAP_KERNEL_AT_EL0 Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-12-12 8:44 ` Geert Uytterhoeven
2017-12-12 8:44 ` Geert Uytterhoeven
2017-12-12 10:28 ` Will Deacon
2017-12-12 10:28 ` Will Deacon
2017-11-30 16:39 ` [PATCH v2 18/18] perf: arm_spe: Disallow userspace profiling when arm_kernel_unmapped_at_el0() Will Deacon
2017-11-30 16:39 ` Will Deacon
2017-12-01 12:15 ` Mark Rutland
2017-12-01 12:15 ` Mark Rutland
2017-12-01 16:49 ` Will Deacon
2017-12-01 16:49 ` Will Deacon
2017-12-01 16:26 ` Stephen Boyd
2017-12-01 16:26 ` Stephen Boyd
2017-12-01 14:04 ` [PATCH v2 00/18] arm64: Unmap the kernel whilst running in userspace (KAISER) Mark Rutland
2017-12-01 14:04 ` Mark Rutland
2017-12-01 17:50 ` Will Deacon
2017-12-01 17:50 ` Will Deacon
2017-12-01 17:58 ` Mark Rutland
2017-12-01 17:58 ` Mark Rutland
2017-12-01 18:02 ` Dave Hansen
2017-12-01 18:02 ` Dave Hansen
2017-12-01 18:14 ` Will Deacon
2017-12-01 18:14 ` Will Deacon
2017-12-11 2:24 ` Shanker Donthineni
2017-12-11 2:24 ` Shanker Donthineni
2017-12-04 23:47 ` Laura Abbott
2017-12-04 23:47 ` Laura Abbott
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