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

[Robert Richter <robert.richter@amd.com>]

On 07.06.11 19:18:22, Robert Richter wrote:
> From c73bebe2e281ae089499d7cbc3b44a0869c8daf8 Mon Sep 17 00:00:00 2001
> From: Robert Richter <robert.richter@amd.com>
> 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@amd.com>
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@amd.com>
---
 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

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



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Operating System Research Center