Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754779Ab3J3UQa (ORCPT ); Wed, 30 Oct 2013 16:16:30 -0400 Received: from merlin.infradead.org ([205.233.59.134]:53911 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752697Ab3J3UQ3 (ORCPT ); Wed, 30 Oct 2013 16:16:29 -0400 Date: Wed, 30 Oct 2013 21:16:22 +0100 From: Peter Zijlstra To: Frederic Weisbecker Cc: will.deacon@arm.com, mingo@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [BUG] perf: arch_perf_out_copy_user default Message-ID: <20131030201622.GR16117@laptop.programming.kicks-ass.net> References: <20131030143750.GT19466@laptop.lan> <20131030195013.GA2253@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131030195013.GA2253@localhost.localdomain> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6116 Lines: 177 On Wed, Oct 30, 2013 at 08:50:28PM +0100, Frederic Weisbecker wrote: > > Would it make sense to rather make copy_from_user_nmi() to use a return value > pattern that is closer to those of the existing copy_from_user_*() ? Yeah we can do that I suppose; copy_form_user_nmi() actually uses __copy_from_user_inatomic() since about a week. Something like so I suppose.. please check, I'm in fail mode. It looks like DEFINE_OUTPUT_COPY() functions already returned the bytes not copied, and all its users appear to indeed expect that. --- arch/x86/kernel/cpu/perf_event.c | 4 ++-- arch/x86/kernel/cpu/perf_event_intel_ds.c | 2 +- arch/x86/kernel/cpu/perf_event_intel_lbr.c | 2 +- arch/x86/lib/usercopy.c | 2 +- arch/x86/oprofile/backtrace.c | 4 ++-- kernel/events/internal.h | 35 ++++++++++++++++++++++-------- 6 files changed, 33 insertions(+), 16 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 94bf3010bb39..0fa7dbe756e6 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -1998,7 +1998,7 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry) frame.return_address = 0; bytes = copy_from_user_nmi(&frame, fp, sizeof(frame)); - if (bytes != sizeof(frame)) + if (bytes != 0) break; if (!valid_user_frame(fp, sizeof(frame))) @@ -2050,7 +2050,7 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs) frame.return_address = 0; bytes = copy_from_user_nmi(&frame, fp, sizeof(frame)); - if (bytes != sizeof(frame)) + if (bytes != 0) break; if (!valid_user_frame(fp, sizeof(frame))) diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c index c1760ff3c757..ae96cfa5eddd 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_ds.c +++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c @@ -789,7 +789,7 @@ static int intel_pmu_pebs_fixup_ip(struct pt_regs *regs) size = ip - to; /* Must fit our buffer, see above */ bytes = copy_from_user_nmi(buf, (void __user *)to, size); - if (bytes != size) + if (bytes != 0) return 0; kaddr = buf; diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c index 90ee6c1d0542..d82d155aca8c 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c @@ -491,7 +491,7 @@ static int branch_type(unsigned long from, unsigned long to, int abort) /* may fail if text not present */ bytes = copy_from_user_nmi(buf, (void __user *)from, size); - if (bytes != size) + if (bytes != 0) return X86_BR_NONE; addr = buf; diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c index 5465b8613944..ddf9ecb53cc3 100644 --- a/arch/x86/lib/usercopy.c +++ b/arch/x86/lib/usercopy.c @@ -31,6 +31,6 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n) ret = __copy_from_user_inatomic(to, from, n); pagefault_enable(); - return n - ret; + return ret; } EXPORT_SYMBOL_GPL(copy_from_user_nmi); diff --git a/arch/x86/oprofile/backtrace.c b/arch/x86/oprofile/backtrace.c index d6aa6e8315d1..5d04be5efb64 100644 --- a/arch/x86/oprofile/backtrace.c +++ b/arch/x86/oprofile/backtrace.c @@ -47,7 +47,7 @@ dump_user_backtrace_32(struct stack_frame_ia32 *head) unsigned long bytes; bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead)); - if (bytes != sizeof(bufhead)) + if (bytes != 0) return NULL; fp = (struct stack_frame_ia32 *) compat_ptr(bufhead[0].next_frame); @@ -93,7 +93,7 @@ static struct stack_frame *dump_user_backtrace(struct stack_frame *head) unsigned long bytes; bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead)); - if (bytes != sizeof(bufhead)) + if (bytes != 0) return NULL; oprofile_add_trace(bufhead[0].return_address); diff --git a/kernel/events/internal.h b/kernel/events/internal.h index ca6599723be5..569b218782ad 100644 --- a/kernel/events/internal.h +++ b/kernel/events/internal.h @@ -82,16 +82,16 @@ static inline unsigned long perf_data_size(struct ring_buffer *rb) } #define DEFINE_OUTPUT_COPY(func_name, memcpy_func) \ -static inline unsigned int \ +static inline unsigned long \ func_name(struct perf_output_handle *handle, \ - const void *buf, unsigned int len) \ + const void *buf, unsigned long len) \ { \ unsigned long size, written; \ \ do { \ - size = min_t(unsigned long, handle->size, len); \ - \ + size = min(handle->size, len); \ written = memcpy_func(handle->addr, buf, size); \ + written = size - written; \ \ len -= written; \ handle->addr += written; \ @@ -110,20 +110,37 @@ func_name(struct perf_output_handle *handle, \ return len; \ } -static inline int memcpy_common(void *dst, const void *src, size_t n) +static inline unsigned long +memcpy_common(void *dst, const void *src, unsigned long n) { memcpy(dst, src, n); - return n; + return 0; } DEFINE_OUTPUT_COPY(__output_copy, memcpy_common) -#define MEMCPY_SKIP(dst, src, n) (n) +static inline unsigned long +memcpy_skip(void *dst, const void *src, unsigned long n) +{ + return 0; +} -DEFINE_OUTPUT_COPY(__output_skip, MEMCPY_SKIP) +DEFINE_OUTPUT_COPY(__output_skip, memcpy_skip) #ifndef arch_perf_out_copy_user -#define arch_perf_out_copy_user __copy_from_user_inatomic +#define arch_perf_out_copy_user arch_perf_out_copy_user + +static inline unsigned long +arch_perf_out_copy_user(void *dst, const void *src, unsigned long n) +{ + unsigned long ret; + + pagefault_disable(); + ret = __copy_from_user_inatomic(dst, src, n); + pagefault_enable(); + + return ret; +} #endif DEFINE_OUTPUT_COPY(__output_copy_user, arch_perf_out_copy_user) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/