Commit 6dd8b1a0 authored by Catalin Marinas's avatar Catalin Marinas Committed by Will Deacon
Browse files

arm64: mte: Dump the MTE tags in the core file 



For each vma mapped with PROT_MTE (the VM_MTE flag set), generate a
PT_ARM_MEMTAG_MTE segment in the core file and dump the corresponding
tags. The in-file size for such segments is 128 bytes per page.

For pages in a VM_MTE vma which are not present in the user page tables
or don't have the PG_mte_tagged flag set (e.g. execute-only), just write
zeros in the core file.

An example of program headers for two vmas, one 2-page, the other 4-page
long:

  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

Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Acked-by: default avatarLuis Machado <luis.machado@linaro.org>
Reviewed-by: default avatarMark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220131165456.2160675-5-catalin.marinas@arm.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent ab1e435c

arch/arm64/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ config ARM64 
	select ACPI_SPCR_TABLE if ACPI

	select ACPI_PPTT if ACPI

	select ARCH_HAS_DEBUG_WX

	select ARCH_BINFMT_ELF_EXTRA_PHDRS

	select ARCH_BINFMT_ELF_STATE

	select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE

	select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION

arch/arm64/kernel/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -61,6 +61,7 @@ obj-$(CONFIG_ARM64_ACPI_PARKING_PROTOCOL) += acpi_parking_protocol.o 
obj-$(CONFIG_PARAVIRT)			+= paravirt.o

obj-$(CONFIG_RANDOMIZE_BASE)		+= kaslr.o

obj-$(CONFIG_HIBERNATION)		+= hibernate.o hibernate-asm.o

obj-$(CONFIG_ELF_CORE)			+= elfcore.o

obj-$(CONFIG_KEXEC_CORE)		+= machine_kexec.o relocate_kernel.o	\

					   cpu-reset.o

obj-$(CONFIG_KEXEC_FILE)		+= machine_kexec_file.o kexec_image.o

arch/arm64/kernel/elfcore.c

0 → 100644
+123 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only



#include <linux/coredump.h>

#include <linux/elfcore.h>

#include <linux/kernel.h>

#include <linux/mm.h>



#include <asm/cpufeature.h>

#include <asm/mte.h>



#define for_each_mte_vma(tsk, vma)					\

	if (system_supports_mte())					\

		for (vma = tsk->mm->mmap; vma; vma = vma->vm_next)	\

			if (vma->vm_flags & VM_MTE)



static unsigned long mte_vma_tag_dump_size(struct vm_area_struct *vma)

{

	if (vma->vm_flags & VM_DONTDUMP)

		return 0;



	return vma_pages(vma) * MTE_PAGE_TAG_STORAGE;

}



/* Derived from dump_user_range(); start/end must be page-aligned */

static int mte_dump_tag_range(struct coredump_params *cprm,

			      unsigned long start, unsigned long end)

{

	unsigned long addr;



	for (addr = start; addr < end; addr += PAGE_SIZE) {

		char tags[MTE_PAGE_TAG_STORAGE];

		struct page *page = get_dump_page(addr);



		/*

		 * get_dump_page() returns NULL when encountering an empty

		 * page table entry that would otherwise have been filled with

		 * the zero page. Skip the equivalent tag dump which would

		 * have been all zeros.

		 */

		if (!page) {

			dump_skip(cprm, MTE_PAGE_TAG_STORAGE);

			continue;

		}



		/*

		 * Pages mapped in user space as !pte_access_permitted() (e.g.

		 * PROT_EXEC only) may not have the PG_mte_tagged flag set.

		 */

		if (!test_bit(PG_mte_tagged, &page->flags)) {

			put_page(page);

			dump_skip(cprm, MTE_PAGE_TAG_STORAGE);

			continue;

		}



		mte_save_page_tags(page_address(page), tags);

		put_page(page);

		if (!dump_emit(cprm, tags, MTE_PAGE_TAG_STORAGE))

			return 0;

	}



	return 1;

}



Elf_Half elf_core_extra_phdrs(void)

{

	struct vm_area_struct *vma;

	int vma_count = 0;



	for_each_mte_vma(current, vma)

		vma_count++;



	return vma_count;

}



int elf_core_write_extra_phdrs(struct coredump_params *cprm, loff_t offset)

{

	struct vm_area_struct *vma;



	for_each_mte_vma(current, vma) {

		struct elf_phdr phdr;



		phdr.p_type = PT_ARM_MEMTAG_MTE;

		phdr.p_offset = offset;

		phdr.p_vaddr = vma->vm_start;

		phdr.p_paddr = 0;

		phdr.p_filesz = mte_vma_tag_dump_size(vma);

		phdr.p_memsz = vma->vm_end - vma->vm_start;

		offset += phdr.p_filesz;

		phdr.p_flags = 0;

		phdr.p_align = 0;



		if (!dump_emit(cprm, &phdr, sizeof(phdr)))

			return 0;

	}



	return 1;

}



size_t elf_core_extra_data_size(void)

{

	struct vm_area_struct *vma;

	size_t data_size = 0;



	for_each_mte_vma(current, vma)

		data_size += mte_vma_tag_dump_size(vma);



	return data_size;

}



int elf_core_write_extra_data(struct coredump_params *cprm)

{

	struct vm_area_struct *vma;



	for_each_mte_vma(current, vma) {

		if (vma->vm_flags & VM_DONTDUMP)

			continue;



		if (!mte_dump_tag_range(cprm, vma->vm_start, vma->vm_end))

			return 0;

	}



	return 1;

}