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authorCatalin Marinas2022-01-31 16:54:55 +0000
committerWill Deacon2022-02-15 22:53:29 +0000
commit6dd8b1a0b6cb3ed93d24110e02e67ff9d006610a (patch)
tree4bbc7dd14cbcdf8fc6b960814d796e2cea96c538 /arch/arm64/kernel
parentab1e435ca7913e384ed801210418633eee43a71b (diff)
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 <catalin.marinas@arm.com> Acked-by: Luis Machado <luis.machado@linaro.org> Reviewed-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20220131165456.2160675-5-catalin.marinas@arm.com Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/kernel')
-rw-r--r--arch/arm64/kernel/Makefile1
-rw-r--r--arch/arm64/kernel/elfcore.c123
2 files changed, 124 insertions, 0 deletions
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 <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;
+}