From: "Luck, Tony" <tony.luck@intel.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Tony Luck <tony.luck@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Borislav Petkov <bp@alien8.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH v13] x86, mce: Add memcpy_trap()
Date: Thu, 25 Feb 2016 11:33:49 -0800 [thread overview]
Message-ID: <56cf571d44495b2cf@agluck-desk.sc.intel.com> (raw)
In-Reply-To: <20160225085624.GA13833@gmail.com>
For reference below is what I'd hoped to be able to do with
copy_from_user() [obviously needs to not just replace that
ALTERNATIVE_2 setup in _copy_from_user ... would have to invent
an ALTERNATIVE_3 to pick the new function for people willing
to sacrifice speed for recoverability]
BUT ... there are a maze of twisty little other places that
also need to be fixed:
1) There is iov_iter_fault_in_readable() that uses fault_in_pages_readable()
to pre-fault the first (and last) page using a raw __get_user() call.
2) I tried to avoid that by injecting my error to the middle of a page,
but still ended up in a "rep mov" copy function instead of mine. Not
sure which one because no output from the core that died. :-(
-Tony
diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S
index 982ce34f4a9b..e31d8964ac09 100644
--- a/arch/x86/lib/copy_user_64.S
+++ b/arch/x86/lib/copy_user_64.S
@@ -38,11 +38,15 @@ ENTRY(_copy_from_user)
jc bad_from_user
cmpq TI_addr_limit(%rax),%rcx
ja bad_from_user
+#if 1
+ jmp copy_from_user_with_mce_check
+#else
ALTERNATIVE_2 "jmp copy_user_generic_unrolled", \
"jmp copy_user_generic_string", \
X86_FEATURE_REP_GOOD, \
"jmp copy_user_enhanced_fast_string", \
X86_FEATURE_ERMS
+#endif
ENDPROC(_copy_from_user)
.section .fixup,"ax"
diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c
index 0a42327a59d7..c377a70474e0 100644
--- a/arch/x86/lib/usercopy_64.c
+++ b/arch/x86/lib/usercopy_64.c
@@ -6,6 +6,8 @@
* Copyright 2002 Andi Kleen <ak@suse.de>
*/
#include <linux/module.h>
+#include <linux/mm.h>
+#include <asm/traps.h>
#include <asm/uaccess.h>
/*
@@ -86,3 +88,25 @@ copy_user_handle_tail(char *to, char *from, unsigned len)
memset(to, 0, len);
return len;
}
+
+__visible unsigned long
+copy_from_user_with_mce_check(void *to, const void __user *from, unsigned n)
+{
+ struct memcpy_trap_ret r;
+
+ stac();
+ r = memcpy_trap(to, (__force void *)from, n);
+ clac();
+
+ if (likely(r.bytes_left == 0))
+ return 0;
+
+ if (r.trap_nr == X86_TRAP_MC) {
+ volatile void *fault_addr = (volatile void *)from + n - r.bytes_left;
+ phys_addr_t p = virt_to_phys(fault_addr);
+
+ memory_failure(p >> PAGE_SHIFT, MCE_VECTOR, 0);
+ }
+
+ return r.bytes_left;
+}
next prev parent reply other threads:[~2016-02-25 19:33 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-17 18:20 [PATCH v11 0/4] Machine check recovery when kernel accesses poison Tony Luck
2016-02-17 18:20 ` [PATCH v11 1/4] x86: Expand exception table to allow new handling options Tony Luck
2016-02-18 10:19 ` [tip:ras/core] x86/mm: Expand the exception table logic " tip-bot for Tony Luck
2016-02-17 18:20 ` [PATCH v11 4/4] x86: Create a new synthetic cpu capability for machine check recovery Tony Luck
2016-02-18 10:19 ` [tip:x86/asm] x86/cpufeature: " tip-bot for Tony Luck
2016-02-17 18:20 ` [PATCH v11 3/4] x86, mce: Add __mcsafe_copy() Tony Luck
2016-02-18 8:21 ` Ingo Molnar
2016-02-18 9:59 ` Peter Zijlstra
2016-02-18 10:19 ` Ingo Molnar
2016-02-18 10:29 ` Borislav Petkov
2016-02-18 10:35 ` Peter Zijlstra
2016-02-18 14:59 ` Luck, Tony
2016-02-19 7:58 ` Ingo Molnar
2016-02-19 8:43 ` Peter Zijlstra
2016-02-19 9:51 ` Ingo Molnar
2016-02-18 10:29 ` Borislav Petkov
2016-02-18 10:34 ` Ingo Molnar
2016-02-18 10:36 ` Borislav Petkov
2016-02-18 18:48 ` Ingo Molnar
2016-02-18 21:14 ` [PATCH v12] x86, mce: Add memcpy_trap() Luck, Tony
2016-02-19 9:10 ` Ingo Molnar
2016-02-19 17:53 ` [PATCH v13] " Luck, Tony
2016-02-24 17:38 ` Tony Luck
2016-02-24 18:35 ` Linus Torvalds
2016-02-24 19:27 ` Tony Luck
2016-02-24 19:37 ` Linus Torvalds
2016-02-25 8:56 ` Ingo Molnar
2016-02-25 19:33 ` Luck, Tony [this message]
2016-02-25 20:39 ` Linus Torvalds
2016-02-25 22:11 ` Andy Lutomirski
2016-02-18 19:47 ` [PATCH v14] x86, mce: Add memcpy_mcsafe() Tony Luck
2016-03-02 20:47 ` Luck, Tony
2016-03-08 17:37 ` [tip:ras/core] x86/mm, x86/mce: " tip-bot for Tony Luck
2016-03-10 19:26 ` [PATCH v14] x86, mce: " Mika Penttilä
2016-03-10 19:37 ` Luck, Tony
2016-03-11 22:10 ` Tony Luck
2016-03-11 22:14 ` Dan Williams
2016-03-12 17:16 ` Ingo Molnar
2016-03-13 1:12 ` Linus Torvalds
2016-03-13 9:25 ` Ingo Molnar
2016-03-14 22:33 ` [PATCH] x86/mm, x86/mce: Fix return type/value for memcpy_mcsafe() Tony Luck
2016-03-16 8:06 ` [tip:x86/urgent] " tip-bot for Tony Luck
2016-02-26 0:58 ` [PATCH v13] x86, mce: Add memcpy_trap() Linus Torvalds
2016-02-26 1:19 ` Andy Lutomirski
2016-02-26 2:38 ` Linus Torvalds
2016-02-18 18:12 ` [PATCH v11 3/4] x86, mce: Add __mcsafe_copy() Linus Torvalds
2016-02-18 18:51 ` Ingo Molnar
2016-02-18 18:52 ` Luck, Tony
2016-02-18 20:14 ` Ingo Molnar
2016-02-18 21:33 ` Dan Williams
2016-02-17 18:20 ` [PATCH v11 2/4] x86, mce: Check for faults tagged in EXTABLE_CLASS_FAULT exception table entries Tony Luck
2016-02-18 10:19 ` [tip:ras/core] x86/mce: " tip-bot for Tony Luck
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