Fix --mem-usage /proc/kcore

makedumpfile --mem-usage /proc/kcore has been broken after kaslr specific modifications. A kernel patch has been ACKed by Andrew Morton and has been sent to Linus now [0]. This kernel patch helps to fix the issue for both the case of kaslr enabled and disabled.

[0] http://marc.info/?l=linux-mm-commits&m=148823497215968&w=2

Changes since v1:
- One more patch..Now mem-usage with older kernel (< 4.11) will only work when that has been rightly patched and -f has been used in makedumpfile command line.

Baoquan He (2):
makedumpfile: Correct the calculation of kvaddr in
set_kcore_vmcoreinfo
makedumpfile: Discard process_dump_load

Pratyush Anand (5):
show_mem_usage(): calculate page offset after elf load initial(): call cach_init() a bit early
x86_64: check physical address in PT_LOAD for none direct mapped
regions
elf_info: kcore: check for invalid physical address
mem-usage: allow to work only with -f for kernel version < 4.11

 arch/x86_64.c  |  6 ++++--
 elf_info.c     | 25 +++++--------------------
 makedumpfile.c | 18 ++++++++++++------
 3 files changed, 21 insertions(+), 28 deletions(-)

PT_LOAD of kcore does not have valid p_paddr values for kernel version less that v4.11. Therefore, older kernel will no long work for mem-usage with current makedumpfile code. They can only work when they are patched with fix to "update physical address for kcore ram and text".

This patch fixes the makedumpfile so that it does not allow to work older kernel for --mem-usage until someone is sure that kernel is rightly patched and so uses -f in command line.

Signed-off-by Pratyush Anand <[email protected]>

---
makedumpfile.c | 6 ++++++

1 file changed, 6 insertions(+)

makedumpfile.c +0 -0

index 3b8e9810468d..bf006ea5dd5f 100644

Hello Pratyush,

Quoted 23 lines

PT_LOAD of kcore does not have valid p_paddr values for kernel version less that v4.11. Therefore, older kernel will no long work for mem-usage with current makedumpfile code. They can only work when they are patched with fix to "update physical address for kcore ram and text".

This patch fixes the makedumpfile so that it does not allow to work older kernel for --mem-usage until someone is sure that kernel is rightly patched and so uses -f in command line.

Signed-off-by Pratyush Anand <[email protected]>

---
makedumpfile.c | 6 ++++++

1 file changed, 6 insertions(+)

makedumpfile.c +1 -0

index 3b8e9810468d..bf006ea5dd5f 100644
@@ -11269,6 +11269,12 @@ main(int argc, char *argv[])
 			MSG("Try `makedumpfile --help' for more information.\n");
 			goto out;
 		}
+		if (info->kernel_version < KERNEL_VERSION(4, 11, 0) &&

makedumpfile.c main(int argc, char *argv[]) · line 11277

Quoted 5 lines

makedumpfile.c +5 -0

+				!info->flag_force) {
+			MSG("mem-usage not supported for this kernel.\n");
+			MSG("You can try with -f if your kernel's kcore has valid p_paddr\n");
+			return COMPLETED;
+		}

Should use "goto out" to prevent memory leaks since some heap blocks are allocated at the head of main().

BTW, the descriptions of -f option in man and print_usage() don't mention this usage:

-f Force existing DUMPFILE to be overwritten.
Example:
# makedumpfile -f -d 31 -x vmlinux /proc/vmcore dumpfile This command overwrites DUMPFILE even if it already exists.

so they should be updated.

Hello Pratyush,

Quoted 23 lines

PT_LOAD of kcore does not have valid p_paddr values for kernel version less that v4.11. Therefore, older kernel will no long work for mem-usage with current makedumpfile code. They can only work when they are patched with fix to "update physical address for kcore ram and text".

This patch fixes the makedumpfile so that it does not allow to work older kernel for --mem-usage until someone is sure that kernel is rightly patched and so uses -f in command line.

Signed-off-by Pratyush Anand <[email protected]>

---
makedumpfile.c | 6 ++++++

1 file changed, 6 insertions(+)

makedumpfile.c +1 -0

index 3b8e9810468d..bf006ea5dd5f 100644
@@ -11269,6 +11269,12 @@ main(int argc, char *argv[])
 			MSG("Try `makedumpfile --help' for more information.\n");
 			goto out;
 		}
+		if (info->kernel_version < KERNEL_VERSION(4, 11, 0) &&

makedumpfile.c main(int argc, char *argv[]) · line 11277

Quoted 5 lines

makedumpfile.c +5 -0

+				!info->flag_force) {
+			MSG("mem-usage not supported for this kernel.\n");
+			MSG("You can try with -f if your kernel's kcore has valid p_paddr\n");
+			return COMPLETED;
+		}

Should use "goto out" to prevent memory leaks since some heap blocks are allocated at the head of main().

BTW, the descriptions of -f option in man and print_usage() don't mention this usage:

-f Force existing DUMPFILE to be overwritten.
Example:
# makedumpfile -f -d 31 -x vmlinux /proc/vmcore dumpfile This command overwrites DUMPFILE even if it already exists.

so they should be updated.

Hi Atsushi,

Quoted 25 lines · Atsushi Kumagai

Hello Pratyush,

Quoted 23 lines

PT_LOAD of kcore does not have valid p_paddr values for kernel version less that v4.11. Therefore, older kernel will no long work for mem-usage with current makedumpfile code. They can only work when they are patched with fix to "update physical address for kcore ram and text".

This patch fixes the makedumpfile so that it does not allow to work older kernel for --mem-usage until someone is sure that kernel is rightly patched and so uses -f in command line.

Signed-off-by Pratyush Anand <[email protected]>

---
makedumpfile.c | 6 ++++++

1 file changed, 6 insertions(+)

makedumpfile.c +1 -0

index 3b8e9810468d..bf006ea5dd5f 100644
@@ -11269,6 +11269,12 @@ main(int argc, char *argv[])
 			MSG("Try `makedumpfile --help' for more information.\n");
 			goto out;
 		}
+		if (info->kernel_version < KERNEL_VERSION(4, 11, 0) &&

Quoted 8 lines

makedumpfile.c main(int argc, char *argv[]) · line 11277

Quoted 5 lines

makedumpfile.c +5 -0

+				!info->flag_force) {
+			MSG("mem-usage not supported for this kernel.\n");
+			MSG("You can try with -f if your kernel's kcore has valid p_paddr\n");
+			return COMPLETED;
+		}

Should use "goto out" to prevent memory leaks since some heap blocks are allocated at the head of main().

OK

Quoted 3 lines

BTW, the descriptions of -f option in man and print_usage() don't mention this usage:

Quoted 6 lines

-f Force existing DUMPFILE to be overwritten.
Example:
# makedumpfile -f -d 31 -x vmlinux /proc/vmcore dumpfile This command overwrites DUMPFILE even if it already exists.

so they should be updated.

Does following looks fine to you?

$ makedumpfile --help | grep -A3 "\-f"
  [-f]:
      Overwrite DUMPFILE even if it already exists
      Force mem-usage to work with older kernel as well.

$ man makedumpfile | grep -w "\-f  " -A6
       -f     Force existing DUMPFILE to be overwritten and mem-usage
to work with older kernel as well.
              Example:
              # makedumpfile -f -d 31 -x vmlinux /proc/vmcore dumpfile
              This command overwrites DUMPFILE even if it already exists.
              # makedumpfile -f --mem-usage /proc/kcore
              Kernel version lesser than v4.11 will not work with
--mem-usage functionality until it has been  patched  with  upstream  commit
              464920104bf7.  Therefore if you have patched your older
kernel then use -f.

Thanks for the review.

~Pratyush