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vmcore: add API to collect hardware dump in second kernel

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The sequence of actions done by device drivers to append their device
specific hardware/firmware logs to /proc/vmcore are as follows:

1. During probe (before hardware is initialized), device drivers
register to the vmcore module (via vmcore_add_device_dump()), with
callback function, along with buffer size and log name needed for
firmware/hardware log collection.

2. vmcore module allocates the buffer with requested size. It adds
an Elf note and invokes the device driver's registered callback
function.

3. Device driver collects all hardware/firmware logs into the buffer
and returns control back to vmcore module.

Ensure that the device dump buffer size is always aligned to page size
so that it can be mmaped.

Also, rename alloc_elfnotes_buf() to vmcore_alloc_buf() to make it more
generic and reserve NT_VMCOREDD note type to indicate vmcore device
dump.

Suggested-by: Eric Biederman <ebiederm@xmission.com>.
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: Ganesh Goudar <ganeshgr@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Rahul Lakkireddy
2018-05-02 15:17:17 +05:30
committed by David S. Miller
parent 289e1f4e9e
commit 2724273e8f
6 changed files with 184 additions and 9 deletions
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include/uapi/linux/elf.h
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@@ -421,6 +421,7 @@ typedef struct elf64_shdr {
#define NT_ARM_SYSTEM_CALL 0x404 /* ARM system call number */
#define NT_ARM_SVE 0x405 /* ARM Scalable Vector Extension registers */
#define NT_ARC_V2 0x600 /* ARCv2 accumulator/extra registers */
#define NT_VMCOREDD 0x700 /* Vmcore Device Dump Note */
/* Note header in a PT_NOTE section */
typedef struct elf32_note {