| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Wed, 5 Mar 2008 17:00:20 +0100
From: Hans Rosenfeld <hans.rosenfeld@....com>
To: Matt Mackall <mpm@...enic.com>
Cc: Dave Hansen <haveblue@...ibm.com>, linux-kernel@...r.kernel.org,
Adam Litke <aglitke@...il.com>, nacc <nacc@...ux.vnet.ibm.com>,
Jon Tollefson <kniht@...ux.vnet.ibm.com>,
Adam Litke <agl@...ux.vnet.ibm.com>
Subject: Re: [RFC][PATCH] make /proc/pid/pagemap work with huge pages and return page size
On Fri, Feb 29, 2008 at 04:46:12PM -0600, Matt Mackall wrote:
> Well in any case, step 1 should be to finalize the interface. Let's
> start with a single patch that does nothing but move the exported bits
> around and makes room for the page shift bits. Are we agreed on what
> that should look like now?
Attached is a patch that changes the current pagemap code just to use
the pseudo-pte, which can now also include swap information. The
pseudo-pte is made available through the linux/pagemap_ppte.h header.
The x86-specific huge page support has been left out for now, so the
interface will return wrong information for huge pages.
There are a few reserved bits in the pte part of the union that could be
used to extend the pfn or add more status bits in future (a ronly bit,
indicating that a page is mapped read-only, has been added, but is
currently not set anywhere). The identical parts of the two bitfields in
the union are the present and swap bits, and the page shift.
Signed-off-by: Hans Rosenfeld <hans.rosenfeld@....com>
---
fs/proc/task_mmu.c | 41 ++++++++++++++++--------------------
include/linux/pagemap_ppte.h | 47 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 65 insertions(+), 23 deletions(-)
create mode 100644 include/linux/pagemap_ppte.h
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 49958cf..958a37a 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -5,6 +5,7 @@
#include <linux/highmem.h>
#include <linux/ptrace.h>
#include <linux/pagemap.h>
+#include <linux/pagemap_ppte.h>
#include <linux/ptrace.h>
#include <linux/mempolicy.h>
#include <linux/swap.h>
@@ -527,16 +528,10 @@ struct pagemapread {
char __user *out, *end;
};
-#define PM_ENTRY_BYTES sizeof(u64)
-#define PM_RESERVED_BITS 3
-#define PM_RESERVED_OFFSET (64 - PM_RESERVED_BITS)
-#define PM_RESERVED_MASK (((1LL<<PM_RESERVED_BITS)-1) << PM_RESERVED_OFFSET)
-#define PM_SPECIAL(nr) (((nr) << PM_RESERVED_OFFSET) | PM_RESERVED_MASK)
-#define PM_NOT_PRESENT PM_SPECIAL(1LL)
-#define PM_SWAP PM_SPECIAL(2LL)
-#define PM_END_OF_BUFFER 1
+#define PM_ENTRY_BYTES sizeof(pagemap_ppte_t)
+#define PM_END_OF_BUFFER 1
-static int add_to_pagemap(unsigned long addr, u64 pfn,
+static int add_to_pagemap(unsigned long addr, pagemap_ppte_t ppte,
struct pagemapread *pm)
{
/*
@@ -545,13 +540,13 @@ static int add_to_pagemap(unsigned long addr, u64 pfn,
* the pfn.
*/
if (pm->out + PM_ENTRY_BYTES >= pm->end) {
- if (copy_to_user(pm->out, &pfn, pm->end - pm->out))
+ if (copy_to_user(pm->out, &ppte, pm->end - pm->out))
return -EFAULT;
pm->out = pm->end;
return PM_END_OF_BUFFER;
}
- if (put_user(pfn, pm->out))
+ if (copy_to_user(pm->out, &ppte, sizeof(ppte)))
return -EFAULT;
pm->out += PM_ENTRY_BYTES;
return 0;
@@ -571,12 +566,6 @@ static int pagemap_pte_hole(unsigned long start, unsigned long end,
return err;
}
-u64 swap_pte_to_pagemap_entry(pte_t pte)
-{
- swp_entry_t e = pte_to_swp_entry(pte);
- return PM_SWAP | swp_type(e) | (swp_offset(e) << MAX_SWAPFILES_SHIFT);
-}
-
static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
void *private)
{
@@ -585,15 +574,21 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
int err = 0;
for (; addr != end; addr += PAGE_SIZE) {
- u64 pfn = PM_NOT_PRESENT;
+ pagemap_ppte_t ppte = PM_NOT_PRESENT;
+
pte = pte_offset_map(pmd, addr);
- if (is_swap_pte(*pte))
- pfn = swap_pte_to_pagemap_entry(*pte);
- else if (pte_present(*pte))
- pfn = pte_pfn(*pte);
+ if (is_swap_pte(*pte)) {
+ swp_entry_t e = pte_to_swp_entry(*pte);
+ ppte.pm_swap = 1;
+ ppte.pm_type = swp_type(e);
+ ppte.pm_offset = swp_offset(e);
+ } else if (pte_present(*pte)) {
+ ppte.pm_present = 1;
+ ppte.pm_frame = pte_pfn(*pte);
+ }
/* unmap so we're not in atomic when we copy to userspace */
pte_unmap(pte);
- err = add_to_pagemap(addr, pfn, pm);
+ err = add_to_pagemap(addr, ppte, pm);
if (err)
return err;
}
diff --git a/include/linux/pagemap_ppte.h b/include/linux/pagemap_ppte.h
new file mode 100644
index 0000000..a983500
--- /dev/null
+++ b/include/linux/pagemap_ppte.h
@@ -0,0 +1,47 @@
+#ifndef _LINUX_PAGEMAP_PPTE_H
+#define _LINUX_PAGEMAP_PPTE_H
+
+#include <linux/types.h>
+
+/*
+ * structure used by /proc/pid/pagemap to describe mappings
+ */
+
+union pagemap_ppte {
+ struct pagemap_ppte_pte {
+ __u64 _shift:6;
+ __u64 _frame:40;
+ __u64 _resvd:15;
+ __u64 _ronly:1;
+ __u64 _swap:1;
+ __u64 _present:1;
+ } pte;
+
+ struct pagemap_ppte_swp {
+ __u64 _shift:6;
+ __u64 _offset:51;
+ __u64 _type:5;
+ __u64 _swap:1;
+ __u64 _present:1;
+ } swp;
+
+ __u64 val;
+};
+
+#define pm_shift pte._shift
+#define pm_frame pte._frame
+#define pm_offset swp._offset
+#define pm_type swp._type
+#define pm_ronly pte._ronly
+#define pm_swap pte._swap
+#define pm_present pte._present
+
+typedef union pagemap_ppte pagemap_ppte_t;
+
+#define PM_NOT_PRESENT ((pagemap_ppte_t) { .pm_present = 0, \
+ .pm_swap = 0, \
+ .pm_offset = 0, \
+ .pm_type = 0, \
+ .pm_shift = PAGE_SHIFT})
+
+#endif /* _LINUX_PAGEMAP_PPTE_H */
--
1.5.3.7
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists