Re: [BUG?] x86_64 : Can not read /dev/kmem ?
On Mon, Mar 14, 2005 at 11:37:19AM +0100, Eric Dumazet wrote:
>
> Hi Andi
>
> I tried to mmap /dev/kmem on x86_64 (linux-2.6.11) and got no success.
>
Here's a patch that fixes the problem to me.
Fix mmap of /dev/kmem. It cannot ever have worked before.
vmalloc is still not supported because that would be more
complicated.
Signed-off-by: Andi Kleen <[EMAIL PROTECTED]>
diff -u linux-2.6.11/drivers/char/mem.c-o linux-2.6.11/drivers/char/mem.c
--- linux-2.6.11/drivers/char/mem.c-o 2004-12-24 22:34:47.0 +0100
+++ linux-2.6.11/drivers/char/mem.c 2005-03-22 12:36:33.852319000 +0100
@@ -211,6 +211,23 @@
return 0;
}
+static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
+{
+unsigned long long val;
+ /*
+* RED-PEN: on some architectures there is more mapped memory
+* than available in mem_map which pfn_valid checks
+* for. Perhaps should add a new macro here.
+*
+* RED-PEN: vmalloc is not supported right now.
+*/
+ if (!pfn_valid(vma->vm_pgoff))
+ return -EIO;
+ val = (u64)vma->vm_pgoff << PAGE_SHIFT;
+ vma->vm_pgoff = __pa(val) >> PAGE_SHIFT;
+ return mmap_mem(file, vma);
+}
+
extern long vread(char *buf, char *addr, unsigned long count);
extern long vwrite(char *buf, char *addr, unsigned long count);
@@ -567,7 +584,6 @@
return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
}
-#define mmap_kmem mmap_mem
#define zero_lseek null_lseek
#define full_lseek null_lseek
#define write_zero write_null
-
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Re: [BUG?] x86_64 : Can not read /dev/kmem ?
On Mon, Mar 14, 2005 at 11:37:19AM +0100, Eric Dumazet wrote:
Hi Andi
I tried to mmap /dev/kmem on x86_64 (linux-2.6.11) and got no success.
Here's a patch that fixes the problem to me.
Fix mmap of /dev/kmem. It cannot ever have worked before.
vmalloc is still not supported because that would be more
complicated.
Signed-off-by: Andi Kleen [EMAIL PROTECTED]
diff -u linux-2.6.11/drivers/char/mem.c-o linux-2.6.11/drivers/char/mem.c
--- linux-2.6.11/drivers/char/mem.c-o 2004-12-24 22:34:47.0 +0100
+++ linux-2.6.11/drivers/char/mem.c 2005-03-22 12:36:33.852319000 +0100
@@ -211,6 +211,23 @@
return 0;
}
+static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
+{
+unsigned long long val;
+ /*
+* RED-PEN: on some architectures there is more mapped memory
+* than available in mem_map which pfn_valid checks
+* for. Perhaps should add a new macro here.
+*
+* RED-PEN: vmalloc is not supported right now.
+*/
+ if (!pfn_valid(vma-vm_pgoff))
+ return -EIO;
+ val = (u64)vma-vm_pgoff PAGE_SHIFT;
+ vma-vm_pgoff = __pa(val) PAGE_SHIFT;
+ return mmap_mem(file, vma);
+}
+
extern long vread(char *buf, char *addr, unsigned long count);
extern long vwrite(char *buf, char *addr, unsigned long count);
@@ -567,7 +584,6 @@
return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
}
-#define mmap_kmem mmap_mem
#define zero_lseek null_lseek
#define full_lseek null_lseek
#define write_zero write_null
-
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Re: [BUG?] x86_64 : Can not read /dev/kmem ?
Sorry for the late answer. On Mon, Mar 14, 2005 at 11:37:19AM +0100, Eric Dumazet wrote: > > Hi Andi > > I tried to read /dev/kmem on x86_64 (linux-2.6.11) and got no success. > > read() or pread() returns EINVAL Yes. I fixed this once for 2.4, but somehow the changes never made it into 2.6. The VFS code doesn't like negative offsets, and the kernel addresses are negative. > > I tried mmap() too : mmap() calls succeed, but as soon the user process > dereference memory, we get : Hmm, looks like a bug yes. I can reproduce it. Thanks for the report. Will investigate later. -Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [BUG?] x86_64 : Can not read /dev/kmem ?
Sorry for the late answer. On Mon, Mar 14, 2005 at 11:37:19AM +0100, Eric Dumazet wrote: Hi Andi I tried to read /dev/kmem on x86_64 (linux-2.6.11) and got no success. read() or pread() returns EINVAL Yes. I fixed this once for 2.4, but somehow the changes never made it into 2.6. The VFS code doesn't like negative offsets, and the kernel addresses are negative. I tried mmap() too : mmap() calls succeed, but as soon the user process dereference memory, we get : Hmm, looks like a bug yes. I can reproduce it. Thanks for the report. Will investigate later. -Andi - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[BUG?] x86_64 : Can not read /dev/kmem ?
Hi Andi
I tried to read /dev/kmem on x86_64 (linux-2.6.11) and got no success.
read() or pread() returns EINVAL
I tried mmap() too : mmap() calls succeed, but as soon the user process
dereference memory, we get :
tinfo: Corrupted page table at address 2aabf800
PGD 8a983067 PUD c7e5a067 PMD 91588067 PTE 8048a025
Bad pagetable: 000d [1] SMP
CPU 0
Modules linked in: ipt_REJECT
Pid: 10892, comm: tinfo Not tainted 2.6.11
RIP: 0033:[<00100562>] [<00100562>]
RSP: 002b:7790 EFLAGS: 00010217
RAX: 2aabf000 RBX: 2abbe000 RCX: 2ac8fc0c
RDX: 0001 RSI: 1000 RDI:
RBP: 77f8 R08: 0003 R09: 8048a000
R10: 0001 R11: 0206 R12: 001005b0
R13: 0001 R14: 2adfdfe8 R15: 00100530
FS: 2abcb970() GS:804866c0() knlGS:
CS: 0010 DS: ES: CR0: 8005003b
CR2: 2aabf800 CR3: 90368000 CR4: 06e0
Process tinfo (pid: 10892, threadinfo 8100901b, task
8100c7d976c0)
RIP [<00100562>] RSP <7790>
Thank you
Eric Dumazet
# cat tinfo.c
#define _XOPEN_SOURCE 500
#include
#include
#include
struct tcp_hashinfo {
struct tcp_ehash_bucket *__tcp_ehash;
struct tcp_bind_hashbucket *__tcp_bhash;
int __tcp_bhash_size;
int __tcp_ehash_size;
} tcp_hashinfo;
#define TCPINFO_ADDR 0x8048a000 /* tcp_hashinfo */
int main()
{
int fd = open("/dev/kmem", O_RDONLY) ;
if (pread(fd, _hashinfo, sizeof(tcp_hashinfo), TCPINFO_ADDR) == -1) {
lseek(fd, TCPINFO_ADDR, 0) ;
if (read(fd, _hashinfo, sizeof(tcp_hashinfo)) == -1) {
perror("Can not read /dev/kmem ?") ;
return 1 ;
}
}
printf("ehash=%p esize=%d bhash=%p bsize=%d\n",
tcp_hashinfo.__tcp_ehash,
tcp_hashinfo.__tcp_ehash_size,
tcp_hashinfo.__tcp_bhash,
tcp_hashinfo.__tcp_bhash_size) ;
return 0 ;
}
-
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[BUG?] x86_64 : Can not read /dev/kmem ?
Hi Andi
I tried to read /dev/kmem on x86_64 (linux-2.6.11) and got no success.
read() or pread() returns EINVAL
I tried mmap() too : mmap() calls succeed, but as soon the user process
dereference memory, we get :
tinfo: Corrupted page table at address 2aabf800
PGD 8a983067 PUD c7e5a067 PMD 91588067 PTE 8048a025
Bad pagetable: 000d [1] SMP
CPU 0
Modules linked in: ipt_REJECT
Pid: 10892, comm: tinfo Not tainted 2.6.11
RIP: 0033:[00100562] [00100562]
RSP: 002b:7790 EFLAGS: 00010217
RAX: 2aabf000 RBX: 2abbe000 RCX: 2ac8fc0c
RDX: 0001 RSI: 1000 RDI:
RBP: 77f8 R08: 0003 R09: 8048a000
R10: 0001 R11: 0206 R12: 001005b0
R13: 0001 R14: 2adfdfe8 R15: 00100530
FS: 2abcb970() GS:804866c0() knlGS:
CS: 0010 DS: ES: CR0: 8005003b
CR2: 2aabf800 CR3: 90368000 CR4: 06e0
Process tinfo (pid: 10892, threadinfo 8100901b, task
8100c7d976c0)
RIP [00100562] RSP 7790
Thank you
Eric Dumazet
# cat tinfo.c
#define _XOPEN_SOURCE 500
#include unistd.h
#include stdio.h
#include fcntl.h
struct tcp_hashinfo {
struct tcp_ehash_bucket *__tcp_ehash;
struct tcp_bind_hashbucket *__tcp_bhash;
int __tcp_bhash_size;
int __tcp_ehash_size;
} tcp_hashinfo;
#define TCPINFO_ADDR 0x8048a000 /* tcp_hashinfo */
int main()
{
int fd = open(/dev/kmem, O_RDONLY) ;
if (pread(fd, tcp_hashinfo, sizeof(tcp_hashinfo), TCPINFO_ADDR) == -1) {
lseek(fd, TCPINFO_ADDR, 0) ;
if (read(fd, tcp_hashinfo, sizeof(tcp_hashinfo)) == -1) {
perror(Can not read /dev/kmem ?) ;
return 1 ;
}
}
printf(ehash=%p esize=%d bhash=%p bsize=%d\n,
tcp_hashinfo.__tcp_ehash,
tcp_hashinfo.__tcp_ehash_size,
tcp_hashinfo.__tcp_bhash,
tcp_hashinfo.__tcp_bhash_size) ;
return 0 ;
}
-
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