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oprofile, x86: Fix nmi-unsafe callgraph support in, 2.6.27 and later

PATCH In review Robert Richter 3 participants 7 messages Jun 7, 2011 – Jul 21, 2011 6 messages not in the archive

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Robert Richter

author
#5 lore raw

PATCH 1/1 oprofile, x86: Fix nmi-unsafe callgraph support in, 2.6.27 and later

Quoted 4 lines · John Lumby

But please do send your fix along and I'll give it a try. I now have
capability for capturing un-syslog'd console messages such as these via serial console so if it happens again I should be able to provide more information.

See the fix below.

-Robert

Quoted 1 line

From c73bebe2e281ae089499d7cbc3b44a0869c8daf8 Mon Sep 17 00:00:00 2001

From: Robert Richter <[email protected]>
Date: Fri, 3 Jun 2011 16:37:47 +0200
Subject: [PATCH] oprofile, x86: Fix nmi-unsafe callgraph support

Current oprofile's x86 callgraph support may trigger page faults throwing the BUG_ON(in_nmi()) message below. This patch fixes this by using the same nmi-safe copy-from-user code as in perf.

------------[ cut here ]------------
kernel BUG at .../arch/x86/kernel/traps.c:436!
invalid opcode: 0000 [#1] SMP
last sysfs file: /sys/devices/pci0000:00/0000:00:0a.0/0000:07:00.0/0000:08:04.0/net/eth0/broadcast
CPU 5
Modules linked in:

Pid: 8611, comm: opcontrol Not tainted 2.6.39-00007-gfe47ae7 #1 Advanced Micro Device Anaheim/Anaheim

RIP: 0010:[<ffffffff813e8e35>]  [<ffffffff813e8e35>] do_nmi+0x22/0x1ee
RSP: 0000:ffff88042fd47f28  EFLAGS: 00010002
RAX: ffff88042c0a7fd8 RBX: 0000000000000001 RCX: 00000000c0000101
RDX: 00000000ffff8804 RSI: ffffffffffffffff RDI: ffff88042fd47f58
RBP: ffff88042fd47f48 R08: 0000000000000004 R09: 0000000000001484
R10: 0000000000000001 R11: 0000000000000000 R12: ffff88042fd47f58
R13: 0000000000000000 R14: ffff88042fd47d98 R15: 0000000000000020
FS:  00007fca25e56700(0000) GS:ffff88042fd40000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000074 CR3: 000000042d28b000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process opcontrol (pid: 8611, threadinfo ffff88042c0a6000, task ffff88042c532310)
Stack:
 0000000000000000 0000000000000001 ffff88042c0a7fd8 0000000000000000
 ffff88042fd47de8 ffffffff813e897a 0000000000000020 ffff88042fd47d98
 0000000000000000 ffff88042c0a7fd8 ffff88042fd47de8 0000000000000074
Call Trace:
 <NMI>
 [<ffffffff813e897a>] nmi+0x1a/0x20
 [<ffffffff813f08ab>] ? bad_to_user+0x25/0x771
 <<EOE>>
Code: ff 59 5b 41 5c 41 5d c9 c3 55 65 48 8b 04 25 88 b5 00 00 48 89 e5 41 55 41 54 49 89 fc 53 48 83 ec 08 f6 80 47 e0 ff ff 04 74 04 <0f> 0b eb fe 81 80 44 e0 ff ff 00 00 01 04 65 ff 04 25 c4 0f 01
RIP  [<ffffffff813e8e35>] do_nmi+0x22/0x1ee
 RSP <ffff88042fd47f28>
---[ end trace ed6752185092104b ]---
Kernel panic - not syncing: Fatal exception in interrupt
Pid: 8611, comm: opcontrol Tainted: G      D     2.6.39-00007-gfe47ae7 #1
Call Trace:
 <NMI>  [<ffffffff813e5e0a>] panic+0x8c/0x188
 [<ffffffff813e915c>] oops_end+0x81/0x8e
 [<ffffffff8100403d>] die+0x55/0x5e
 [<ffffffff813e8c45>] do_trap+0x11c/0x12b
 [<ffffffff810023c8>] do_invalid_op+0x91/0x9a
 [<ffffffff813e8e35>] ? do_nmi+0x22/0x1ee
 [<ffffffff8131e6fa>] ? oprofile_add_sample+0x83/0x95
 [<ffffffff81321670>] ? op_amd_check_ctrs+0x4f/0x2cf
 [<ffffffff813ee4d5>] invalid_op+0x15/0x20
 [<ffffffff813e8e35>] ? do_nmi+0x22/0x1ee
 [<ffffffff813e8e7a>] ? do_nmi+0x67/0x1ee
 [<ffffffff813e897a>] nmi+0x1a/0x20
 [<ffffffff813f08ab>] ? bad_to_user+0x25/0x771
 <<EOE>>
Cc John Lumby <[email protected]>
Cc Maynard Johnson <[email protected]>
Cc <[email protected]> # .37+
Signed-off-by Robert Richter <[email protected]>
---
 arch/x86/oprofile/backtrace.c |   56 ++++++++++++++++++++++++++++++++++------
 1 files changed, 47 insertions(+), 9 deletions(-)
arch/x86/oprofile/backtrace.c +47 -9
index 2d49d4e..88e856e 100644
@@ -11,10 +11,12 @@
 #include <linux/oprofile.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
+#include <linux/compat.h>
+#include <linux/highmem.h>
+
 #include <asm/ptrace.h>
 #include <asm/uaccess.h>
 #include <asm/stacktrace.h>
-#include <linux/compat.h>
 
 static void backtrace_warning_symbol(void *data, char *msg,
 				     unsigned long symbol)

@@ -49,17 +51,53 @@ 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)
 {
+	/* Also check accessibility of one struct frame_head beyond: */
 	struct stack_frame_ia32 bufhead[2];
 	struct stack_frame_ia32 *fp;
+	unsigned long bytes;
 
-	/* Also check accessibility of one struct frame_head beyond */
-	if (!access_ok(VERIFY_READ, head, sizeof(bufhead)))
-		return NULL;
-	if (__copy_from_user_inatomic(bufhead, head, sizeof(bufhead)))
+	bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead));
+	if (bytes != sizeof(bufhead))
 		return NULL;
 
 	fp = (struct stack_frame_ia32 *) compat_ptr(bufhead[0].next_frame);

@@ -100,12 +138,12 @@ x86_backtrace_32(struct pt_regs * const regs, unsigned int depth)
 
 static struct stack_frame *dump_user_backtrace(struct stack_frame *head)
 {
+	/* Also check accessibility of one struct frame_head beyond: */
 	struct stack_frame bufhead[2];
+	unsigned long bytes;
 
-	/* Also check accessibility of one struct stack_frame beyond */
-	if (!access_ok(VERIFY_READ, head, sizeof(bufhead)))
-		return NULL;
-	if (__copy_from_user_inatomic(bufhead, head, sizeof(bufhead)))
+	bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead));
+	if (bytes != sizeof(bufhead))
 		return NULL;
 
 	oprofile_add_trace(bufhead[0].return_address);
Signature · 7 lines
1.7.5.rc3



-- 
Advanced Micro Devices, Inc.
Operating System Research Center
author
#6 lore raw

RFC PATCH 1/1 x86: Make copy_from_user_nmi() a library function

Quoted 4 lines · Robert Richter

From c73bebe2e281ae089499d7cbc3b44a0869c8daf8 Mon Sep 17 00:00:00 2001
From: Robert Richter <[email protected]>
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

Quoted 1 line

From 3652d1b07a0cfce5b26ad186594c1bf8f9ca5898 Mon Sep 17 00:00:00 2001

From: Robert Richter <[email protected]>
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 <[email protected]>
---
 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
arch/x86/include/asm/uaccess.h +3 -0
index abd3e0e..c0236e9 100644
@@ -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
  */
arch/x86/kernel/cpu/perf_event.c +0 -35
index e638689..46bf36d 100644
@@ -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)];
arch/x86/lib/Makefile +1 -1
index f2479f1..6ba4773 100644
@@ -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
arch/x86/lib/usercopy.c new file +43 -0

43 lines not on this page · raw message

arch/x86/oprofile/backtrace.c +1 -38
index 88e856e..087233f 100644
@@ -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)
Signature · 7 lines
1.7.5.rc3



-- 
Advanced Micro Devices, Inc.
Operating System Research Center
#7 lore raw

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

On Tue, Jun 07, 2011 at 07:24:13PM +0200, Robert Richter wrote:
... (unrelated a bit) ...

arch/x86/lib/usercopy.c line 29

Quoted 4 lines
arch/x86/lib/usercopy.c new file +4 -0
+
+		offset = addr & (PAGE_SIZE - 1);
+		size = min(PAGE_SIZE - offset, n - len);
+

...

Robert, would not offset = addr & ~PAGE_MASK be somehow more readable? Just a thought.

Cyrill

author
#8 lore raw

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

In reply to Robert Richter
Quoted 22 lines · Robert Richter
Quoted 4 lines · Robert Richter

From c73bebe2e281ae089499d7cbc3b44a0869c8daf8 Mon Sep 17 00:00:00 2001
From: Robert Richter <[email protected]>
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 <[email protected]>
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 <[email protected]>
Quoted 8 lines
---
 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

Quoted 197 lines
arch/x86/include/asm/uaccess.h +3 -0
index abd3e0e..c0236e9 100644
@@ -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
  */
arch/x86/kernel/cpu/perf_event.c +0 -35
index e638689..46bf36d 100644
@@ -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)];
arch/x86/lib/Makefile +1 -1
index f2479f1..6ba4773 100644
@@ -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
arch/x86/lib/usercopy.c new file +43 -0
new file mode 100644
index 0000000..4ef83d3
@@ -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);
arch/x86/oprofile/backtrace.c +1 -38
index 88e856e..087233f 100644
@@ -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)
Signature · 7 lines
1.7.5.rc3



-- 
Advanced Micro Devices, Inc.
Operating System Research Center
Signature · 2 lines
Advanced Micro Devices, Inc.
Operating System Research Center
maintainer
#9 lore raw

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

Quoted 4 lines · Robert Richter

Ingo, Peter,

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

Ah, thanks for the reminder, yeah, took it with EXPORT_SYMBOL_GPL.

---
Subject: x86: Make copy_from_user_nmi() a library function
From: Robert Richter <[email protected]>
Date: Tue, 7 Jun 2011 11:49:55 +0200

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 <[email protected]>
Signed-off-by Peter Zijlstra <[email protected]>
Link http://lkml.kernel.org/r/[email protected] open here
---
 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
arch/x86/include/asm/uaccess.h +3 -0
Index: linux-2.6/arch/x86/include/asm/uaccess.h
===================================================================
@@ -555,6 +555,9 @@ struct __large_struct { unsigned long bu
 
 #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
  */
arch/x86/kernel/cpu/perf_event.c +0 -35
Index: linux-2.6/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>
 

@@ -67,40 +66,6 @@ enum extra_reg_type {
 	EXTRA_REG_MAX		/* number of entries needed */
 };
 
-/*
- * 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)];
arch/x86/lib/Makefile +1 -1
Index: linux-2.6/arch/x86/lib/Makefile
===================================================================
@@ -18,7 +18,7 @@ obj-$(CONFIG_SMP) += msr-smp.o cache-smp
 
 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
arch/x86/lib/usercopy.c new file +43 -0

43 lines not on this page · raw message

arch/x86/oprofile/backtrace.c +1 -38
Index: linux-2.6/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 int backtrace_stack(void *data, char *name)

@@ -38,42 +37,6 @@ static struct stacktrace_ops backtrace_o
 	.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)
author
#10 lore raw

[tip:perf/core] x86, perf: Make copy_from_user_nmi() a library function

In reply to Robert Richter
Commit-ID:  1ac2e6ca44e13a087eb7438d284f887097ee7e84
Gitweb:     http://git.kernel.org/tip/1ac2e6ca44e13a087eb7438d284f887097ee7e84
Author:     Robert Richter <[email protected]>
AuthorDate: Tue, 7 Jun 2011 11:49:55 +0200
Committer:  Ingo Molnar <[email protected]>
CommitDate: Thu, 21 Jul 2011 20:41:57 +0200

x86, perf: 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 <[email protected]>
Signed-off-by Peter Zijlstra <[email protected]>
Link http://lkml.kernel.org/r/[email protected] open here
Signed-off-by Ingo Molnar <[email protected]>
---
 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(-)
arch/x86/include/asm/uaccess.h +3 -0
index 99ddd14..36361bf 100644
@@ -555,6 +555,9 @@ 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
  */
arch/x86/kernel/cpu/perf_event.c +0 -35
index b7a010f..4ee3abf 100644
@@ -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>
 

@@ -67,40 +66,6 @@ enum extra_reg_type {
 	EXTRA_REG_MAX		/* number of entries needed */
 };
 
-/*
- * 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)];
arch/x86/lib/Makefile +1 -1
index f2479f1..6ba4773 100644
@@ -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
arch/x86/lib/usercopy.c new file +43 -0

43 lines not on this page · raw message

arch/x86/oprofile/backtrace.c +1 -38
index 32f78eb..bff89df 100644
@@ -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 int backtrace_stack(void *data, char *name)

@@ -38,42 +37,6 @@ 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)

A message that is not in the archive (sent off-list or not yet received): [email protected]

author
#12 lore raw
Quoted 4 lines · John Lumby

I am also a bit confused by the kernel's statement that it's a NULL
pointer deref. I had previously found that the pointer contains
0x0000000a, not NULL. Does the kernel call it NULL for any invalid
value? Or am I misunderstanding it. Anyway ...

0x0000000a is also considered a NULL pointer access, typically this happens if a member of a struct which points to NULL is accessed.

Quoted 5 lines

Have you or anyone tried this on an intel x86? I'm just curious
whether it's everyone or only me.

From your other mail:

"EIP is at print_context_stack=0x45/0xb0

and from a machine-code listing, I found that that offset corresponds to the line

       addr = *stack;

in arch/x86/kernel/dumpstack.c"

Actually this should not happen, because of checking the stack pointer in valid_stack_ptr(). So could you apply the change below and test if this throws a bug message?

Thanks,

-Robert

arch/x86/kernel/dumpstack.c +2 -0
index e2a3f06..37693f5 100644
@@ -73,6 +73,8 @@ static inline int valid_stack_ptr(struct thread_info *tinfo,
                        void *p, unsigned int size, void *end)
 {
        void *t = tinfo;
+
+       BUG_ON(p < (void *)THREAD_SIZE);
        if (end) {
                if (p < end && p >= (end-THREAD_SIZE))
                        return 1;
Signature · 2 lines
Advanced Micro Devices, Inc.
Operating System Research Center