cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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elfcore.c (2922B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2
      3#include <linux/coredump.h>
      4#include <linux/elfcore.h>
      5#include <linux/kernel.h>
      6#include <linux/mm.h>
      7
      8#include <asm/cpufeature.h>
      9#include <asm/mte.h>
     10
     11#define for_each_mte_vma(tsk, vma)					\
     12	if (system_supports_mte())					\
     13		for (vma = tsk->mm->mmap; vma; vma = vma->vm_next)	\
     14			if (vma->vm_flags & VM_MTE)
     15
     16static unsigned long mte_vma_tag_dump_size(struct vm_area_struct *vma)
     17{
     18	if (vma->vm_flags & VM_DONTDUMP)
     19		return 0;
     20
     21	return vma_pages(vma) * MTE_PAGE_TAG_STORAGE;
     22}
     23
     24/* Derived from dump_user_range(); start/end must be page-aligned */
     25static int mte_dump_tag_range(struct coredump_params *cprm,
     26			      unsigned long start, unsigned long end)
     27{
     28	int ret = 1;
     29	unsigned long addr;
     30	void *tags = NULL;
     31
     32	for (addr = start; addr < end; addr += PAGE_SIZE) {
     33		struct page *page = get_dump_page(addr);
     34
     35		/*
     36		 * get_dump_page() returns NULL when encountering an empty
     37		 * page table entry that would otherwise have been filled with
     38		 * the zero page. Skip the equivalent tag dump which would
     39		 * have been all zeros.
     40		 */
     41		if (!page) {
     42			dump_skip(cprm, MTE_PAGE_TAG_STORAGE);
     43			continue;
     44		}
     45
     46		/*
     47		 * Pages mapped in user space as !pte_access_permitted() (e.g.
     48		 * PROT_EXEC only) may not have the PG_mte_tagged flag set.
     49		 */
     50		if (!test_bit(PG_mte_tagged, &page->flags)) {
     51			put_page(page);
     52			dump_skip(cprm, MTE_PAGE_TAG_STORAGE);
     53			continue;
     54		}
     55
     56		if (!tags) {
     57			tags = mte_allocate_tag_storage();
     58			if (!tags) {
     59				put_page(page);
     60				ret = 0;
     61				break;
     62			}
     63		}
     64
     65		mte_save_page_tags(page_address(page), tags);
     66		put_page(page);
     67		if (!dump_emit(cprm, tags, MTE_PAGE_TAG_STORAGE)) {
     68			mte_free_tag_storage(tags);
     69			ret = 0;
     70			break;
     71		}
     72	}
     73
     74	if (tags)
     75		mte_free_tag_storage(tags);
     76
     77	return ret;
     78}
     79
     80Elf_Half elf_core_extra_phdrs(void)
     81{
     82	struct vm_area_struct *vma;
     83	int vma_count = 0;
     84
     85	for_each_mte_vma(current, vma)
     86		vma_count++;
     87
     88	return vma_count;
     89}
     90
     91int elf_core_write_extra_phdrs(struct coredump_params *cprm, loff_t offset)
     92{
     93	struct vm_area_struct *vma;
     94
     95	for_each_mte_vma(current, vma) {
     96		struct elf_phdr phdr;
     97
     98		phdr.p_type = PT_AARCH64_MEMTAG_MTE;
     99		phdr.p_offset = offset;
    100		phdr.p_vaddr = vma->vm_start;
    101		phdr.p_paddr = 0;
    102		phdr.p_filesz = mte_vma_tag_dump_size(vma);
    103		phdr.p_memsz = vma->vm_end - vma->vm_start;
    104		offset += phdr.p_filesz;
    105		phdr.p_flags = 0;
    106		phdr.p_align = 0;
    107
    108		if (!dump_emit(cprm, &phdr, sizeof(phdr)))
    109			return 0;
    110	}
    111
    112	return 1;
    113}
    114
    115size_t elf_core_extra_data_size(void)
    116{
    117	struct vm_area_struct *vma;
    118	size_t data_size = 0;
    119
    120	for_each_mte_vma(current, vma)
    121		data_size += mte_vma_tag_dump_size(vma);
    122
    123	return data_size;
    124}
    125
    126int elf_core_write_extra_data(struct coredump_params *cprm)
    127{
    128	struct vm_area_struct *vma;
    129
    130	for_each_mte_vma(current, vma) {
    131		if (vma->vm_flags & VM_DONTDUMP)
    132			continue;
    133
    134		if (!mte_dump_tag_range(cprm, vma->vm_start, vma->vm_end))
    135			return 0;
    136	}
    137
    138	return 1;
    139}