| Message ID | 20220131165456.2160675-1-catalin.marinas@arm.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | arm64: mte: add core dump support | expand |
On Mon, 31 Jan 2022 16:54:51 +0000, Catalin Marinas wrote: > This is the second version of the core dump support for MTE tags. > Changes since v1 > (https://lore.kernel.org/r/20211208121941.494956-1-catalin.marinas@arm.com): > > - Made the documentation slightly clearer on what the size of a segment. > - Added Luis' acks. > - Rebased to 5.17-rc2. > > [...] Applied to arm64 (for-next/mte), thanks! [1/5] elfcore: Replace CONFIG_{IA64, UML} checks with a new option https://git.kernel.org/arm64/c/b62a8486de3a [2/5] elf: Introduce the ARM MTE ELF segment type https://git.kernel.org/arm64/c/761b9b366cec [3/5] arm64: mte: Define the number of bytes for storing the tags in a page https://git.kernel.org/arm64/c/ab1e435ca791 [4/5] arm64: mte: Dump the MTE tags in the core file https://git.kernel.org/arm64/c/6dd8b1a0b6cb [5/5] arm64: mte: Document the core dump file format https://git.kernel.org/arm64/c/731451ab3c0c Cheers,
Hi, This is the second version of the core dump support for MTE tags. Changes since v1 (https://lore.kernel.org/r/20211208121941.494956-1-catalin.marinas@arm.com): - Made the documentation slightly clearer on what the size of a segment. - Added Luis' acks. - Rebased to 5.17-rc2. The arm64 Memory Tagging Extensions allow assigning a 4-bit (allocation) tag to a 16-byte memory range. Bits 56..59 of a pointer are checked against the allocation tag on access and a fault may be raised if there's a mismatch. The additional 4-bit metadata is useful for debugging hence this series to dump it to the core file. When a core file is generated and the user has mappings with PROT_MTE, segments with the PT_ARM_MEMTAG_MTE type are dumped. These correspond to the PT_LOAD segments for the same virtual addresses. The choice of an ELF segment rather than a note was made due to the 32-bit size limitation of a note which would only cover vmas up to 37-bit. The last patch documents the core file format. The tags are dumped packed, two 4-bit tags per byte (unlike ptrace where we have one tag per byte) and there is no header to define the format, it's all fixed for the PT_ARM_MEMTAG_MTE type. Below you can see the output of 'readelf -a core' for a program mapping two regions with PROT_MTE, one 2-page and the other 4-page long. Half of the first page in each range was filled with 0xa and 0xb tags respectively. Program Headers: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align ... LOAD 0x030000 0x0000ffff80034000 0x0000000000000000 0x000000 0x002000 RW 0x1000 LOAD 0x030000 0x0000ffff80036000 0x0000000000000000 0x004000 0x004000 RW 0x1000 ... LOPROC+0x1 0x05b000 0x0000ffff80034000 0x0000000000000000 0x000100 0x002000 0 LOPROC+0x1 0x05b100 0x0000ffff80036000 0x0000000000000000 0x000200 0x004000 0 The relevant 'od -tx1 core' output: 05b000 bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb * 05b040 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 * 05b100 aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa * 05b140 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 * 05b300 Catalin Marinas (5): elfcore: Replace CONFIG_{IA64,UML} checks with a new option elf: Introduce the ARM MTE ELF segment type arm64: mte: Define the number of bytes for storing the tags in a page arm64: mte: Dump the MTE tags in the core file arm64: mte: Document the core dump file format .../arm64/memory-tagging-extension.rst | 23 ++++ arch/arm64/Kconfig | 1 + arch/arm64/include/asm/mte-def.h | 1 + arch/arm64/kernel/Makefile | 1 + arch/arm64/kernel/elfcore.c | 123 ++++++++++++++++++ arch/arm64/lib/mte.S | 4 +- arch/arm64/mm/mteswap.c | 2 +- arch/ia64/Kconfig | 1 + arch/x86/um/Kconfig | 1 + fs/Kconfig.binfmt | 3 + include/linux/elfcore.h | 4 +- include/uapi/linux/elf.h | 3 + 12 files changed, 162 insertions(+), 5 deletions(-) create mode 100644 arch/arm64/kernel/elfcore.c