Re: [RFC] [PATCH] x86: Make copy_from_user_nmi() a library function

From: Robert Richter
Date: Tue Jul 05 2011 - 13:23:56 EST

On 07.06.11 19:24:13, Robert Richter wrote:
> On 07.06.11 19:18:22, Robert Richter wrote:
> > From c73bebe2e281ae089499d7cbc3b44a0869c8daf8 Mon Sep 17 00:00:00 2001
> > From: Robert Richter <robert.richter@xxxxxxx>
> > Date: Fri, 3 Jun 2011 16:37:47 +0200
> > Subject: [PATCH] oprofile, x86: Fix nmi-unsafe callgraph support
>
> While this patch was a stable fix which introduced duplicate code for
> perf and oprofile I suggest merging the code, see the patch below.
>
> -Robert
>
>
> From 3652d1b07a0cfce5b26ad186594c1bf8f9ca5898 Mon Sep 17 00:00:00 2001
> From: Robert Richter <robert.richter@xxxxxxx>
> Date: Tue, 7 Jun 2011 11:49:55 +0200
> Subject: [PATCH] x86: Make copy_from_user_nmi() a library function
>
> copy_from_user_nmi() is used in oprofile and perf. Moving it to other
> library functions like copy_from_user(). As this is x86 code for 32
> and 64 bits, create a new file usercopy.c for unified code.
>
> Signed-off-by: Robert Richter <robert.richter@xxxxxxx>
> ---
> arch/x86/include/asm/uaccess.h | 3 ++
> arch/x86/kernel/cpu/perf_event.c | 35 ------------------------------
> arch/x86/lib/Makefile | 2 +-
> arch/x86/lib/usercopy.c | 43 ++++++++++++++++++++++++++++++++++++++
> arch/x86/oprofile/backtrace.c | 39 +---------------------------------
> 5 files changed, 48 insertions(+), 74 deletions(-)
> create mode 100644 arch/x86/lib/usercopy.c

Ingo, Peter,

what about this patch? Any opinion? This one should be against
tip/perf/core now.

Thanks,

-Robert

>
> diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
> index abd3e0e..c0236e9 100644
> --- a/arch/x86/include/asm/uaccess.h
> +++ b/arch/x86/include/asm/uaccess.h
> @@ -556,6 +556,9 @@ struct __large_struct { unsigned long buf[100]; };
>
> #endif /* CONFIG_X86_WP_WORKS_OK */
>
> +extern unsigned long
> +copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
> +
> /*
> * movsl can be slow when source and dest are not both 8-byte aligned
> */
> diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
> index e638689..46bf36d 100644
> --- a/arch/x86/kernel/cpu/perf_event.c
> +++ b/arch/x86/kernel/cpu/perf_event.c
> @@ -22,7 +22,6 @@
> #include <linux/sched.h>
> #include <linux/uaccess.h>
> #include <linux/slab.h>
> -#include <linux/highmem.h>
> #include <linux/cpu.h>
> #include <linux/bitops.h>
>
> @@ -43,40 +42,6 @@ do { \
> } while (0)
> #endif
>
> -/*
> - * best effort, GUP based copy_from_user() that assumes IRQ or NMI context
> - */
> -static unsigned long
> -copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
> -{
> - unsigned long offset, addr = (unsigned long)from;
> - unsigned long size, len = 0;
> - struct page *page;
> - void *map;
> - int ret;
> -
> - do {
> - ret = __get_user_pages_fast(addr, 1, 0, &page);
> - if (!ret)
> - break;
> -
> - offset = addr & (PAGE_SIZE - 1);
> - size = min(PAGE_SIZE - offset, n - len);
> -
> - map = kmap_atomic(page);
> - memcpy(to, map+offset, size);
> - kunmap_atomic(map);
> - put_page(page);
> -
> - len += size;
> - to += size;
> - addr += size;
> -
> - } while (len < n);
> -
> - return len;
> -}
> -
> struct event_constraint {
> union {
> unsigned long idxmsk[BITS_TO_LONGS(X86_PMC_IDX_MAX)];
> diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
> index f2479f1..6ba4773 100644
> --- a/arch/x86/lib/Makefile
> +++ b/arch/x86/lib/Makefile
> @@ -18,7 +18,7 @@ obj-$(CONFIG_SMP) += msr-smp.o cache-smp.o
>
> lib-y := delay.o
> lib-y += thunk_$(BITS).o
> -lib-y += usercopy_$(BITS).o getuser.o putuser.o
> +lib-y += usercopy_$(BITS).o usercopy.o getuser.o putuser.o
> lib-y += memcpy_$(BITS).o
> lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o
>
> diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c
> new file mode 100644
> index 0000000..4ef83d3
> --- /dev/null
> +++ b/arch/x86/lib/usercopy.c
> @@ -0,0 +1,43 @@
> +/*
> + * User address space access functions.
> + *
> + * For licencing details see kernel-base/COPYING
> + */
> +
> +#include <linux/highmem.h>
> +#include <linux/module.h>
> +
> +/*
> + * best effort, GUP based copy_from_user() that assumes IRQ or NMI context
> + */
> +unsigned long
> +copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
> +{
> + unsigned long offset, addr = (unsigned long)from;
> + unsigned long size, len = 0;
> + struct page *page;
> + void *map;
> + int ret;
> +
> + do {
> + ret = __get_user_pages_fast(addr, 1, 0, &page);
> + if (!ret)
> + break;
> +
> + offset = addr & (PAGE_SIZE - 1);
> + size = min(PAGE_SIZE - offset, n - len);
> +
> + map = kmap_atomic(page);
> + memcpy(to, map+offset, size);
> + kunmap_atomic(map);
> + put_page(page);
> +
> + len += size;
> + to += size;
> + addr += size;
> +
> + } while (len < n);
> +
> + return len;
> +}
> +EXPORT_SYMBOL(copy_from_user_nmi);
> diff --git a/arch/x86/oprofile/backtrace.c b/arch/x86/oprofile/backtrace.c
> index 88e856e..087233f 100644
> --- a/arch/x86/oprofile/backtrace.c
> +++ b/arch/x86/oprofile/backtrace.c
> @@ -12,10 +12,9 @@
> #include <linux/sched.h>
> #include <linux/mm.h>
> #include <linux/compat.h>
> -#include <linux/highmem.h>
> +#include <linux/uaccess.h>
>
> #include <asm/ptrace.h>
> -#include <asm/uaccess.h>
> #include <asm/stacktrace.h>
>
> static void backtrace_warning_symbol(void *data, char *msg,
> @@ -51,42 +50,6 @@ static struct stacktrace_ops backtrace_ops = {
> .walk_stack = print_context_stack,
> };
>
> -/* from arch/x86/kernel/cpu/perf_event.c: */
> -
> -/*
> - * best effort, GUP based copy_from_user() that assumes IRQ or NMI context
> - */
> -static unsigned long
> -copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
> -{
> - unsigned long offset, addr = (unsigned long)from;
> - unsigned long size, len = 0;
> - struct page *page;
> - void *map;
> - int ret;
> -
> - do {
> - ret = __get_user_pages_fast(addr, 1, 0, &page);
> - if (!ret)
> - break;
> -
> - offset = addr & (PAGE_SIZE - 1);
> - size = min(PAGE_SIZE - offset, n - len);
> -
> - map = kmap_atomic(page);
> - memcpy(to, map+offset, size);
> - kunmap_atomic(map);
> - put_page(page);
> -
> - len += size;
> - to += size;
> - addr += size;
> -
> - } while (len < n);
> -
> - return len;
> -}
> -
> #ifdef CONFIG_COMPAT
> static struct stack_frame_ia32 *
> dump_user_backtrace_32(struct stack_frame_ia32 *head)
> --
> 1.7.5.rc3
>
>
>
> --
> Advanced Micro Devices, Inc.
> Operating System Research Center

--
Advanced Micro Devices, Inc.
Operating System Research Center

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