[RFC 1/1] mm: add virt to phys debug
From: Jiri Slaby
Date: Thu May 01 2008 - 15:47:57 EST
Christoph Lameter wrote:
> --- linux-2.6.25-mm1.orig/include/asm-x86/page_32.h 2008-04-25 23:17:31.882389317 -0700
>
> +++ linux-2.6.25-mm1/include/asm-x86/page_32.h 2008-04-25 23:37:43.202391820 -0700
>
> @@ -64,8 +64,13 @@
>
> typedef·struct·page·*pgtable_t;
> #endif
> #ifndef·__ASSEMBLY__
> -#define·__phys_addr(x)» » ((x)·-·PAGE_OFFSET)
> +static·inline·unsigned·long·__phys_addr(unsigned·long·x)
> +{
> + VM_BUG_ON(is_vmalloc_addr((void·*)x));
> + return·x·-·PAGE_OFFSET;
> +}
> +
> #define·__phys_reloc_hide(x)» RELOC_HIDE((x),·0)
> #ifdef·CONFIG_FLATMEM
Christoph, was you able to compile this somehow? I had to move the code
into ioremap along 64-bit variant to allow the checking.
A pacth which I created is attached, I've successfully tested it by this
module:
static int init1(void)
{
static int data;
struct module *mod = THIS_MODULE;
char *k = (void *)PAGE_OFFSET;
char *m = mod->module_core;
char *sl = kmalloc(1000, GFP_KERNEL);
char *pg = (void *)__get_free_page(GFP_KERNEL);
char *rnd;
printk(KERN_WARNING "OK\n");
printk(KERN_WARNING "%p -> %lx\n", &data, vmalloc_to_pfn(&data));
printk(KERN_WARNING "%p -> %lx\n", m, vmalloc_to_pfn(m));
printk(KERN_WARNING "%p -> %lx\n", k, virt_to_phys(k));
printk(KERN_WARNING "%p -> %lx\n", sl, virt_to_phys(sl));
printk(KERN_WARNING "%p -> %lx\n", pg, virt_to_phys(pg));
printk(KERN_WARNING "failing\n");
printk(KERN_WARNING "%p -> %lx\n", &data, virt_to_phys(&data));
printk(KERN_WARNING "%p -> %lx\n", m, virt_to_phys(m));
printk(KERN_WARNING "%p -> %lx\n", k, vmalloc_to_pfn(k));
printk(KERN_WARNING "%p -> %lx\n", sl, vmalloc_to_pfn(sl));
printk(KERN_WARNING "%p -> %lx\n", pg, vmalloc_to_pfn(pg));
#ifdef CONFIG_X86_64
rnd = (void *)0xffffc10000000000;
printk(KERN_WARNING "%p -> %lx\n", rnd, vmalloc_to_pfn(rnd));
printk(KERN_WARNING "%p -> %lx\n", rnd, virt_to_phys(rnd));
rnd = (void *)0xffff800000000000;
printk(KERN_WARNING "%p -> %lx\n", rnd, vmalloc_to_pfn(rnd));
printk(KERN_WARNING "%p -> %lx\n", rnd, virt_to_phys(rnd));
rnd = (void *)0xffffe2ffffffffff + 1;
printk(KERN_WARNING "%p -> %lx\n", rnd, vmalloc_to_pfn(rnd));
printk(KERN_WARNING "%p -> %lx\n", rnd, virt_to_phys(rnd));
rnd = (void *)0xffffe20000000000;
printk(KERN_WARNING "%p -> %lx\n", rnd, virt_to_phys(rnd));
#endif
kfree(sl);
free_page((ulong)pg);
return -EIO;
}
Please comment. (At least if leave 2 debug macros or only single one.)
--
Add some (configurable) expensive sanity checking to catch wrong address
translations on x86.
- create linux/mmdebug.h file to be able include this file in
asm headers to not get unsolvable loops in header files
- __phys_addr on x86_32 became a function in ioremap.c since
PAGE_OFFSET and is_vmalloc_addr is undefined if declared in
page_32.h (again circular dependencies)
- add __phys_addr_const for initializing doublefault_tss.__cr3
Tested on 386, 386pae, x86_64 and x86_64 numa=fake=2.
Signed-off-by: Jiri Slaby <jirislaby@xxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Christoph Lameter <clameter@xxxxxxx>
---
arch/x86/Kconfig.debug | 7 -------
arch/x86/kernel/doublefault_32.c | 2 +-
arch/x86/mm/ioremap.c | 31 ++++++++++++++++++++++++-------
include/asm-x86/mmzone_64.h | 6 +-----
include/asm-x86/page_32.h | 3 ++-
include/linux/mm.h | 7 +------
include/linux/mmdebug.h | 18 ++++++++++++++++++
lib/Kconfig.debug | 9 +++++++++
mm/vmalloc.c | 5 +++++
9 files changed, 61 insertions(+), 27 deletions(-)
create mode 100644 include/linux/mmdebug.h
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 33b4388..6396ee0 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -258,13 +258,6 @@ config CPA_DEBUG
help
Do change_page_attr() self-tests every 30 seconds.
-config DEBUG_VIRTUAL
- bool "Virtual memory translation debugging"
- depends on DEBUG_KERNEL && NUMA && X86_64
- help
- Enable some costly sanity checks in the NUMA virtual to page
- code. This can catch mistakes with virt_to_page() and friends.
-
endmenu
config OPTIMIZE_INLINING
diff --git a/arch/x86/kernel/doublefault_32.c b/arch/x86/kernel/doublefault_32.c
index a47798b..395acb1 100644
--- a/arch/x86/kernel/doublefault_32.c
+++ b/arch/x86/kernel/doublefault_32.c
@@ -66,6 +66,6 @@ struct tss_struct doublefault_tss __cacheline_aligned = {
.ds = __USER_DS,
.fs = __KERNEL_PERCPU,
- .__cr3 = __pa(swapper_pg_dir)
+ .__cr3 = __phys_addr_const((unsigned long)swapper_pg_dir)
}
};
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 6d96353..5ead5a8 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -23,18 +23,26 @@
#ifdef CONFIG_X86_64
-unsigned long __phys_addr(unsigned long x)
+static inline int phys_addr_valid(unsigned long addr)
{
- if (x >= __START_KERNEL_map)
- return x - __START_KERNEL_map + phys_base;
- return x - PAGE_OFFSET;
+ return addr < (1UL << boot_cpu_data.x86_phys_bits);
}
-EXPORT_SYMBOL(__phys_addr);
-static inline int phys_addr_valid(unsigned long addr)
+unsigned long __phys_addr(unsigned long x)
{
- return addr < (1UL << boot_cpu_data.x86_phys_bits);
+ if (x >= __START_KERNEL_map) {
+ x -= __START_KERNEL_map;
+ VIRTUAL_BUG_ON(x >= KERNEL_IMAGE_SIZE);
+ x += phys_base;
+ } else {
+ VIRTUAL_BUG_ON(x < PAGE_OFFSET);
+ x -= PAGE_OFFSET;
+ VIRTUAL_BUG_ON(system_state == SYSTEM_BOOTING ? x > MAXMEM :
+ !phys_addr_valid(x));
+ }
+ return x;
}
+EXPORT_SYMBOL(__phys_addr);
#else
@@ -43,6 +51,15 @@ static inline int phys_addr_valid(unsigned long addr)
return 1;
}
+unsigned long __phys_addr(unsigned long x)
+{
+ /* VMALLOC_* aren't constants; not available at the boot time */
+ VIRTUAL_BUG_ON(x < PAGE_OFFSET || (system_state != SYSTEM_BOOTING &&
+ is_vmalloc_addr((void *)x)));
+ return x - PAGE_OFFSET;
+}
+EXPORT_SYMBOL(__phys_addr);
+
#endif
int page_is_ram(unsigned long pagenr)
diff --git a/include/asm-x86/mmzone_64.h b/include/asm-x86/mmzone_64.h
index 8e64d67..facde3e 100644
--- a/include/asm-x86/mmzone_64.h
+++ b/include/asm-x86/mmzone_64.h
@@ -7,11 +7,7 @@
#ifdef CONFIG_NUMA
-#ifdef CONFIG_DEBUG_VIRTUAL
-#define VIRTUAL_BUG_ON(x) BUG_ON(x)
-#else
-#define VIRTUAL_BUG_ON(x)
-#endif
+#include <linux/mmdebug.h>
#include <asm/smp.h>
diff --git a/include/asm-x86/page_32.h b/include/asm-x86/page_32.h
index 424e82f..9159bfb 100644
--- a/include/asm-x86/page_32.h
+++ b/include/asm-x86/page_32.h
@@ -64,7 +64,8 @@ typedef struct page *pgtable_t;
#endif
#ifndef __ASSEMBLY__
-#define __phys_addr(x) ((x) - PAGE_OFFSET)
+#define __phys_addr_const(x) ((x) - PAGE_OFFSET)
+extern unsigned long __phys_addr(unsigned long);
#define __phys_reloc_hide(x) RELOC_HIDE((x), 0)
#ifdef CONFIG_FLATMEM
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 438ee65..5e002dc 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -7,6 +7,7 @@
#include <linux/gfp.h>
#include <linux/list.h>
+#include <linux/mmdebug.h>
#include <linux/mmzone.h>
#include <linux/rbtree.h>
#include <linux/prio_tree.h>
@@ -210,12 +211,6 @@ struct inode;
*/
#include <linux/page-flags.h>
-#ifdef CONFIG_DEBUG_VM
-#define VM_BUG_ON(cond) BUG_ON(cond)
-#else
-#define VM_BUG_ON(condition) do { } while(0)
-#endif
-
/*
* Methods to modify the page usage count.
*
diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h
new file mode 100644
index 0000000..860ed1a
--- /dev/null
+++ b/include/linux/mmdebug.h
@@ -0,0 +1,18 @@
+#ifndef LINUX_MM_DEBUG_H
+#define LINUX_MM_DEBUG_H 1
+
+#include <linux/autoconf.h>
+
+#ifdef CONFIG_DEBUG_VM
+#define VM_BUG_ON(cond) BUG_ON(cond)
+#else
+#define VM_BUG_ON(cond) do { } while(0)
+#endif
+
+#ifdef CONFIG_DEBUG_VIRTUAL
+#define VIRTUAL_BUG_ON(cond) BUG_ON(cond)
+#else
+#define VIRTUAL_BUG_ON(cond) do { } while(0)
+#endif
+
+#endif
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index f75f6c1..eb643cb 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -472,6 +472,15 @@ config DEBUG_VM
If unsure, say N.
+config DEBUG_VIRTUAL
+ bool "Debug VM translations"
+ depends on DEBUG_KERNEL && X86
+ help
+ Enable some costly sanity checks in virtual to page code. This can
+ catch mistakes with virt_to_page() and friends.
+
+ If unsure, say N.
+
config DEBUG_WRITECOUNT
bool "Debug filesystem writers count"
depends on DEBUG_KERNEL
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 2a39cf1..c8172db 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -180,6 +180,11 @@ struct page *vmalloc_to_page(const void *vmalloc_addr)
pmd_t *pmd;
pte_t *ptep, pte;
+ /* XXX we might need to change this if we add VIRTUAL_BUG_ON for
+ * architectures that do not vmalloc module space */
+ VIRTUAL_BUG_ON(!is_vmalloc_addr(vmalloc_addr) &&
+ !is_module_address(addr));
+
if (!pgd_none(*pgd)) {
pud = pud_offset(pgd, addr);
if (!pud_none(*pud)) {
--
1.5.4.5
--
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