78 lines
2.5 KiB
Diff
78 lines
2.5 KiB
Diff
From: Mans Rullgard <mans@mansr.com>
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Date: Sat, 16 Aug 2008 23:03:06 +0000 (+0100)
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Subject: ARM: Workaround for erratum 451034
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X-Git-Url: http://git.mansr.com/?p=linux-omap;a=commitdiff_plain;h=b84fa87873ffb68ad23930cf6cddeea8bec43ede
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ARM: Workaround for erratum 451034
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On Cortex-A8 r1p0 and r1p1, executing a NEON store with an integer
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store in the store buffer, can cause a processor deadlock under
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certain conditions.
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Executing a DMB instruction before saving NEON/VFP registers and before
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return to userspace makes it safe to run code which includes similar
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counter-measures. Userspace code can still trigger the deadlock, so
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a different workaround is required to safely run untrusted code.
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See ARM Cortex-A8 Errata Notice (PR120-PRDC-008070) for full details.
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Signed-off-by: Mans Rullgard <mans@mansr.com>
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---
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diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
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index aa475d9..41d536e 100644
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--- a/arch/arm/Kconfig
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+++ b/arch/arm/Kconfig
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@@ -1117,6 +1117,22 @@ config NEON
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Say Y to include support code for NEON, the ARMv7 Advanced SIMD
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Extension.
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+config ARM_ERRATUM_451034
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+ bool "Enable workaround for ARM erratum 451034"
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+ depends on VFPv3
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+ help
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+ On Cortex-A8 r1p0 and r1p1, executing a NEON store with an integer
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+ store in the store buffer, can cause a processor deadlock under
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+ certain conditions.
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+
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+ See ARM Cortex-A8 Errata Notice (PR120-PRDC-008070) for full details.
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+
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+ Say Y to include a partial workaround.
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+
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+ WARNING: Even with this option enabled, userspace code can trigger
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+ the deadlock. To safely run untrusted code, a different fix is
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+ required.
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+
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endmenu
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menu "Userspace binary formats"
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diff --git a/arch/arm/include/asm/vfpmacros.h b/arch/arm/include/asm/vfpmacros.h
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index 422f3cc..934798b 100644
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--- a/arch/arm/include/asm/vfpmacros.h
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+++ b/arch/arm/include/asm/vfpmacros.h
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@@ -32,6 +32,9 @@
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@ write all the working registers out of the VFP
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.macro VFPFSTMIA, base, tmp
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+#ifdef CONFIG_ARM_ERRATUM_451034
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+ dmb
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+#endif
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#if __LINUX_ARM_ARCH__ < 6
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STC p11, cr0, [\base],#33*4 @ FSTMIAX \base!, {d0-d15}
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#else
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diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
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index 060d7e2..9799a35 100644
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--- a/arch/arm/kernel/entry-common.S
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+++ b/arch/arm/kernel/entry-common.S
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@@ -69,6 +69,10 @@ no_work_pending:
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/* perform architecture specific actions before user return */
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arch_ret_to_user r1, lr
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+#ifdef CONFIG_ARM_ERRATUM_451034
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+ dmb
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+#endif
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+
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@ slow_restore_user_regs
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ldr r1, [sp, #S_PSR] @ get calling cpsr
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ldr lr, [sp, #S_PC]! @ get pc
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