On Wed, Sep 23, 2020 at 09:41:33AM -0700, Dan Williams wrote:
The rename replaces a single top-level memcpy_mcsafe() with either copy_mc_to_user(), or copy_mc_to_kernel().
What is "copy_mc" supposed to mean? Especially if it is called that on two arches...
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 7101ac64bb20..e876b3a087f9 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -75,7 +75,7 @@ config X86 select ARCH_HAS_PTE_DEVMAP if X86_64 select ARCH_HAS_PTE_SPECIAL select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
- select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE
- select ARCH_HAS_COPY_MC if X86_64
X86_MCE is dropped here. So if I have a build which has
# CONFIG_X86_MCE is not set
One of those quirks like:
/* * CAPID0{7:6} indicate whether this is an advanced RAS SKU * CAPID5{8:5} indicate that various NVDIMM usage modes are * enabled, so memory machine check recovery is also enabled. */ if ((capid0 & 0xc0) == 0xc0 || (capid5 & 0x1e0)) enable_copy_mc_fragile();
will still call enable_copy_mc_fragile() and none of those platforms need MCE functionality?
But there's a hunk in here which sets it in the MCE code:
if (mca_cfg.recovery) enable_copy_mc_fragile();
So which is it? They need it or they don't?
The comment over copy_mc_to_kernel() says:
* Call into the 'fragile' version on systems that have trouble * actually do machine check recovery
If CONFIG_X86_MCE is not set, I'll say. :)
+++ b/arch/x86/lib/copy_mc.c @@ -0,0 +1,66 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright(c) 2016-2020 Intel Corporation. All rights reserved. */
+#include <linux/jump_label.h> +#include <linux/uaccess.h> +#include <linux/export.h> +#include <linux/string.h> +#include <linux/types.h>
+static DEFINE_STATIC_KEY_FALSE(copy_mc_fragile_key);
+void enable_copy_mc_fragile(void) +{
- static_branch_inc(©_mc_fragile_key);
+}
+/**
- copy_mc_to_kernel - memory copy that that handles source exceptions
One "that" is enough.
...