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Document pagemap futher

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Ciro Santilli
2017-08-04 08:21:20 +01:00
parent bb419de1fe
commit 1f4f7faeba
2 changed files with 23 additions and 6 deletions
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13
kernel_module/user/common.h
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@@ -7,12 +7,15 @@
#include <stdlib.h> /* size_t */ #include <stdlib.h> /* size_t */
#include <unistd.h> /* pread, sysconf */ #include <unistd.h> /* pread, sysconf */
/* Format documented at:
* https://github.com/torvalds/linux/blob/v4.9/Documentation/vm/pagemap.txt
**/
typedef struct { typedef struct {
uint64_t pfn : 54; uint64_t pfn : 54;
unsigned int soft_dirty : 1; unsigned int soft_dirty : 1;
unsigned int file_page : 1; unsigned int file_page : 1;
unsigned int swapped : 1; unsigned int swapped : 1;
unsigned int present : 1; unsigned int present : 1;
} PagemapEntry; } PagemapEntry;
/* Parse the pagemap entry for the given virtual address. /* Parse the pagemap entry for the given virtual address.

16
kernel_module/user/pagemap_dump.c
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@@ -9,6 +9,19 @@ Adapted from: https://github.com/dwks/pagemap/blob/8a25747bc79d6080c8b94eac80807
Dump the page map of a given process PID. Dump the page map of a given process PID.
Data sources: /proc/PIC/{map,pagemap} Data sources: /proc/PIC/{map,pagemap}
This program works in two steps:
- parse the human readable lines lines from `/proc/<pid>/maps`. This files contains lines of form:
7ffff7b6d000-7ffff7bdd000 r-xp 00000000 fe:00 658 /lib/libuClibc-1.0.22.so
which gives us:
- `7f8af99f8000-7f8af99ff000`: a virtual address range that belong to the process, possibly containing multiple pages.
- `/lib/libuClibc-1.0.22.so` the name of the library that owns that memory.
- loop over each page of each address range, and ask `/proc/<pid>/pagemap` for more information about that page, including the physical address.
*/ */
#define _XOPEN_SOURCE 700 #define _XOPEN_SOURCE 700
@@ -22,7 +35,8 @@ Data sources: /proc/PIC/{map,pagemap}
#include "common.h" /* pagemap_get_entry */ #include "common.h" /* pagemap_get_entry */
int main(int argc, char **argv) { int main(int argc, char **argv)
{
char buffer[BUFSIZ]; char buffer[BUFSIZ];
char maps_file[BUFSIZ]; char maps_file[BUFSIZ];
char pagemap_file[BUFSIZ]; char pagemap_file[BUFSIZ];