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68cffbbd44
Teach GDB how to dump memory tags for AArch64 when using the gcore command and how to read memory tag data back from a core file generated by GDB (via gcore) or by the Linux kernel. The format is documented in the Linux Kernel documentation [1]. Each tagged memory range (listed in /proc/<pid>/smaps) gets dumped to its own PT_AARCH64_MEMTAG_MTE segment. A section named ".memtag" is created for each of those segments when reading the core file back. To save a little bit of space, given MTE tags only take 4 bits, the memory tags are stored packed as 2 tags per byte. When reading the data back, the tags are unpacked. I've added a new testcase to exercise the feature. Build-tested with --enable-targets=all and regression tested on aarch64-linux Ubuntu 20.04. [1] Documentation/arm64/memory-tagging-extension.rst (Core Dump Support)
134 lines
3.5 KiB
C
134 lines
3.5 KiB
C
/* Common Linux target-dependent functionality for AArch64 MTE
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Copyright (C) 2021-2022 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "arch/aarch64-mte-linux.h"
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/* See arch/aarch64-mte-linux.h */
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void
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aarch64_mte_pack_tags (gdb::byte_vector &tags)
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{
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/* Nothing to pack? */
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if (tags.empty ())
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return;
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/* If the tags vector has an odd number of elements, add another
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zeroed-out element to make it even. This facilitates packing. */
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if ((tags.size () % 2) != 0)
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tags.emplace_back (0);
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for (int unpacked = 0, packed = 0; unpacked < tags.size ();
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unpacked += 2, packed++)
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tags[packed] = (tags[unpacked + 1] << 4) | tags[unpacked];
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/* Now we have half the size. */
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tags.resize (tags.size () / 2);
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}
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/* See arch/aarch64-mte-linux.h */
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void
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aarch64_mte_unpack_tags (gdb::byte_vector &tags, bool skip_first)
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{
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/* Nothing to unpack? */
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if (tags.empty ())
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return;
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/* An unpacked MTE tags vector will have twice the number of elements
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compared to an unpacked one. */
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gdb::byte_vector unpacked_tags (tags.size () * 2);
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int unpacked = 0, packed = 0;
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if (skip_first)
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{
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/* We are not interested in the first unpacked element, just discard
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it. */
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unpacked_tags[unpacked] = (tags[packed] >> 4) & 0xf;
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unpacked++;
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packed++;
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}
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for (; packed < tags.size (); unpacked += 2, packed++)
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{
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unpacked_tags[unpacked] = tags[packed] & 0xf;
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unpacked_tags[unpacked + 1] = (tags[packed] >> 4) & 0xf;
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}
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/* Update the original tags vector. */
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tags = std::move (unpacked_tags);
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}
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/* See arch/aarch64-mte-linux.h */
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size_t
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aarch64_mte_get_tag_granules (CORE_ADDR addr, size_t len, size_t granule_size)
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{
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/* An empty range has 0 tag granules. */
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if (len == 0)
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return 0;
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/* Start address */
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CORE_ADDR s_addr = align_down (addr, granule_size);
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/* End address */
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CORE_ADDR e_addr = align_down (addr + len - 1, granule_size);
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/* We always have at least 1 granule because len is non-zero at this
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point. */
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return 1 + (e_addr - s_addr) / granule_size;
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}
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/* See arch/aarch64-mte-linux.h */
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CORE_ADDR
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aarch64_mte_make_ltag_bits (CORE_ADDR value)
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{
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return value & AARCH64_MTE_LOGICAL_MAX_VALUE;
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}
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/* See arch/aarch64-mte-linux.h */
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CORE_ADDR
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aarch64_mte_make_ltag (CORE_ADDR value)
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{
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return (aarch64_mte_make_ltag_bits (value)
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<< AARCH64_MTE_LOGICAL_TAG_START_BIT);
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}
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/* See arch/aarch64-mte-linux.h */
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CORE_ADDR
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aarch64_mte_set_ltag (CORE_ADDR address, CORE_ADDR tag)
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{
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/* Remove the existing tag. */
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address &= ~aarch64_mte_make_ltag (AARCH64_MTE_LOGICAL_MAX_VALUE);
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/* Return the new tagged address. */
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return address | aarch64_mte_make_ltag (tag);
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}
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/* See arch/aarch64-mte-linux.h */
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CORE_ADDR
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aarch64_mte_get_ltag (CORE_ADDR address)
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{
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CORE_ADDR ltag_addr = address >> AARCH64_MTE_LOGICAL_TAG_START_BIT;
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return aarch64_mte_make_ltag_bits (ltag_addr);
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}
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