From: Dan Williams <dan.j.williams@intel.com> To: linux-nvdimm@lists.01.org Cc: tony.luck@intel.com, Peter Zijlstra <peterz@infradead.org>, linux-kernel@vger.kernel.org, x86@kernel.org, hch@lst.de, Andy Lutomirski <luto@amacapital.net>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, Al Viro <viro@zeniv.linux.org.uk>, linux-fsdevel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>, Linus Torvalds <torvalds@linux-foundation.org>, Andrew Morton <akpm@linux-foundation.org> Subject: [PATCH v2 4/9] x86, memcpy_mcsafe: add write-protection-fault handling Date: Wed, 02 May 2018 21:59:02 -0700 [thread overview] Message-ID: <152532354268.17218.11923624861859552990.stgit@dwillia2-desk3.amr.corp.intel.com> (raw) In-Reply-To: <152532351517.17218.3583455156840230837.stgit@dwillia2-desk3.amr.corp.intel.com> In preparation for using memcpy_mcsafe() to handle user copies it needs to be to handle write-protection faults while writing user pages. Add MMU-fault handlers alongside the machine-check exception handlers. Note that the machine check fault exception handling makes assumptions about source buffer alignment and poison alignment. In the write fault case, given the destination buffer is arbitrarily aligned, it needs a separate / additional fault handling approach. The mcsafe_handle_tail() helper is reused. The @limit argument is set to @len since there is no safety concern about retriggering an MMU fault, and this simplifies the assembly. Cc: <x86@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Tony Luck <tony.luck@intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Co-developed-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> --- arch/x86/include/asm/uaccess_64.h | 3 +++ arch/x86/lib/memcpy_64.S | 14 ++++++++++++++ arch/x86/lib/usercopy_64.c | 17 +++++++++++++++++ 3 files changed, 34 insertions(+) diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h index 62546b3a398e..c63efc07891f 100644 --- a/arch/x86/include/asm/uaccess_64.h +++ b/arch/x86/include/asm/uaccess_64.h @@ -194,4 +194,7 @@ __copy_from_user_flushcache(void *dst, const void __user *src, unsigned size) unsigned long copy_user_handle_tail(char *to, char *from, unsigned len); +unsigned long +mcsafe_handle_tail(char *to, char *from, unsigned len); + #endif /* _ASM_X86_UACCESS_64_H */ diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S index f01a88391c98..c3b527a9f95d 100644 --- a/arch/x86/lib/memcpy_64.S +++ b/arch/x86/lib/memcpy_64.S @@ -265,9 +265,23 @@ EXPORT_SYMBOL_GPL(__memcpy_mcsafe) mov %ecx, %eax ret + /* + * For write fault handling, given the destination is unaligned, + * we handle faults on multi-byte writes with a byte-by-byte + * copy up to the write-protected page. + */ +.E_write_words: + shll $3, %ecx + addl %edx, %ecx + movl %ecx, %edx + jmp mcsafe_handle_tail + .previous _ASM_EXTABLE_FAULT(.L_read_leading_bytes, .E_leading_bytes) _ASM_EXTABLE_FAULT(.L_read_words, .E_read_words) _ASM_EXTABLE_FAULT(.L_read_trailing_bytes, .E_trailing_bytes) + _ASM_EXTABLE(.L_write_leading_bytes, .E_leading_bytes) + _ASM_EXTABLE(.L_write_words, .E_write_words) + _ASM_EXTABLE(.L_write_trailing_bytes, .E_trailing_bytes) #endif diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c index 75d3776123cc..9787f5ee0cf9 100644 --- a/arch/x86/lib/usercopy_64.c +++ b/arch/x86/lib/usercopy_64.c @@ -75,6 +75,23 @@ copy_user_handle_tail(char *to, char *from, unsigned len) return len; } +/* + * Similar to copy_user_handle_tail, probe for the write fault point, + * but reuse __memcpy_mcsafe in case a new read error is encountered. + * clac() is handled in _copy_to_iter_mcsafe(). + */ +__visible unsigned long +mcsafe_handle_tail(char *to, char *from, unsigned len) +{ + for (; len; --len, to++) { + unsigned long rem = memcpy_mcsafe(to, from, 1); + + if (rem) + break; + } + return len; +} + #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE /** * clean_cache_range - write back a cache range with CLWB _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm
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From: Dan Williams <dan.j.williams@intel.com> To: linux-nvdimm@lists.01.org Cc: x86@kernel.org, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, Tony Luck <tony.luck@intel.com>, Al Viro <viro@zeniv.linux.org.uk>, Thomas Gleixner <tglx@linutronix.de>, Andy Lutomirski <luto@amacapital.net>, Peter Zijlstra <peterz@infradead.org>, Andrew Morton <akpm@linux-foundation.org>, Linus Torvalds <torvalds@linux-foundation.org>, hch@lst.de, linux-kernel@vger.kernel.org, tony.luck@intel.com, linux-fsdevel@vger.kernel.org Subject: [PATCH v2 4/9] x86, memcpy_mcsafe: add write-protection-fault handling Date: Wed, 02 May 2018 21:59:02 -0700 [thread overview] Message-ID: <152532354268.17218.11923624861859552990.stgit@dwillia2-desk3.amr.corp.intel.com> (raw) In-Reply-To: <152532351517.17218.3583455156840230837.stgit@dwillia2-desk3.amr.corp.intel.com> In preparation for using memcpy_mcsafe() to handle user copies it needs to be to handle write-protection faults while writing user pages. Add MMU-fault handlers alongside the machine-check exception handlers. Note that the machine check fault exception handling makes assumptions about source buffer alignment and poison alignment. In the write fault case, given the destination buffer is arbitrarily aligned, it needs a separate / additional fault handling approach. The mcsafe_handle_tail() helper is reused. The @limit argument is set to @len since there is no safety concern about retriggering an MMU fault, and this simplifies the assembly. Cc: <x86@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Tony Luck <tony.luck@intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Co-developed-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> --- arch/x86/include/asm/uaccess_64.h | 3 +++ arch/x86/lib/memcpy_64.S | 14 ++++++++++++++ arch/x86/lib/usercopy_64.c | 17 +++++++++++++++++ 3 files changed, 34 insertions(+) diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h index 62546b3a398e..c63efc07891f 100644 --- a/arch/x86/include/asm/uaccess_64.h +++ b/arch/x86/include/asm/uaccess_64.h @@ -194,4 +194,7 @@ __copy_from_user_flushcache(void *dst, const void __user *src, unsigned size) unsigned long copy_user_handle_tail(char *to, char *from, unsigned len); +unsigned long +mcsafe_handle_tail(char *to, char *from, unsigned len); + #endif /* _ASM_X86_UACCESS_64_H */ diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S index f01a88391c98..c3b527a9f95d 100644 --- a/arch/x86/lib/memcpy_64.S +++ b/arch/x86/lib/memcpy_64.S @@ -265,9 +265,23 @@ EXPORT_SYMBOL_GPL(__memcpy_mcsafe) mov %ecx, %eax ret + /* + * For write fault handling, given the destination is unaligned, + * we handle faults on multi-byte writes with a byte-by-byte + * copy up to the write-protected page. + */ +.E_write_words: + shll $3, %ecx + addl %edx, %ecx + movl %ecx, %edx + jmp mcsafe_handle_tail + .previous _ASM_EXTABLE_FAULT(.L_read_leading_bytes, .E_leading_bytes) _ASM_EXTABLE_FAULT(.L_read_words, .E_read_words) _ASM_EXTABLE_FAULT(.L_read_trailing_bytes, .E_trailing_bytes) + _ASM_EXTABLE(.L_write_leading_bytes, .E_leading_bytes) + _ASM_EXTABLE(.L_write_words, .E_write_words) + _ASM_EXTABLE(.L_write_trailing_bytes, .E_trailing_bytes) #endif diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c index 75d3776123cc..9787f5ee0cf9 100644 --- a/arch/x86/lib/usercopy_64.c +++ b/arch/x86/lib/usercopy_64.c @@ -75,6 +75,23 @@ copy_user_handle_tail(char *to, char *from, unsigned len) return len; } +/* + * Similar to copy_user_handle_tail, probe for the write fault point, + * but reuse __memcpy_mcsafe in case a new read error is encountered. + * clac() is handled in _copy_to_iter_mcsafe(). + */ +__visible unsigned long +mcsafe_handle_tail(char *to, char *from, unsigned len) +{ + for (; len; --len, to++) { + unsigned long rem = memcpy_mcsafe(to, from, 1); + + if (rem) + break; + } + return len; +} + #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE /** * clean_cache_range - write back a cache range with CLWB
next prev parent reply other threads:[~2018-05-03 5:08 UTC|newest] Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-05-03 4:58 [PATCH v2 0/9] use memcpy_mcsafe() for copy_to_iter() Dan Williams 2018-05-03 4:58 ` Dan Williams 2018-05-03 4:58 ` [PATCH v2 1/9] x86, memcpy_mcsafe: remove loop unrolling Dan Williams 2018-05-03 4:58 ` Dan Williams 2018-05-03 4:58 ` [PATCH v2 2/9] x86, memcpy_mcsafe: add labels for write fault handling Dan Williams 2018-05-03 4:58 ` Dan Williams 2018-05-03 4:58 ` [PATCH v2 3/9] x86, memcpy_mcsafe: return bytes remaining Dan Williams 2018-05-03 4:58 ` Dan Williams 2018-05-03 4:59 ` Dan Williams [this message] 2018-05-03 4:59 ` [PATCH v2 4/9] x86, memcpy_mcsafe: add write-protection-fault handling Dan Williams 2018-05-03 5:29 ` Mika Penttilä 2018-05-03 5:29 ` Mika Penttilä 2018-05-03 5:29 ` Mika Penttilä 2018-05-03 14:19 ` Dan Williams 2018-05-03 14:19 ` Dan Williams 2018-05-03 4:59 ` [PATCH v2 5/9] x86, memcpy_mcsafe: define copy_to_iter_mcsafe() Dan Williams 2018-05-03 4:59 ` Dan Williams 2018-05-03 4:59 ` [PATCH v2 6/9] dax: introduce a ->copy_to_iter dax operation Dan Williams 2018-05-03 4:59 ` Dan Williams 2018-05-03 4:59 ` [PATCH v2 7/9] dax: report bytes remaining in dax_iomap_actor() Dan Williams 2018-05-03 4:59 ` Dan Williams 2018-05-03 4:59 ` [PATCH v2 8/9] pmem: switch to copy_to_iter_mcsafe() Dan Williams 2018-05-03 4:59 ` Dan Williams 2018-05-03 4:59 ` [PATCH v2 9/9] x86, nfit_test: unit test for memcpy_mcsafe() Dan Williams 2018-05-03 4:59 ` Dan Williams
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