From 6dd8b1a0b6cb3ed93d24110e02e67ff9d006610a Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Mon, 31 Jan 2022 16:54:55 +0000 Subject: [PATCH] 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: Catalin Marinas Acked-by: Luis Machado Reviewed-by: Mark Brown Link: https://lore.kernel.org/r/20220131165456.2160675-5-catalin.marinas@arm.com Signed-off-by: Will Deacon --- arch/arm64/Kconfig | 1 + arch/arm64/kernel/Makefile | 1 + arch/arm64/kernel/elfcore.c | 123 ++++++++++++++++++++++++++++++++++++ 3 files changed, 125 insertions(+) create mode 100644 arch/arm64/kernel/elfcore.c diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index cbcd42decb2a..b55c11796fad 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -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 diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 88b3e2a21408..986837d7ec82 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -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 diff --git a/arch/arm64/kernel/elfcore.c b/arch/arm64/kernel/elfcore.c new file mode 100644 index 000000000000..3455ee4acc04 --- /dev/null +++ b/arch/arm64/kernel/elfcore.c @@ -0,0 +1,123 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include +#include +#include +#include + +#include +#include + +#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; +}