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![Stephen Boyd](/assets/img/avatar_default.png)
[ Upstream commite6b842741b
] An oops can be induced by running 'cat /proc/kcore > /dev/null' on devices using pstore with the ram backend because kmap_atomic() assumes lowmem pages are accessible with __va(). Unable to handle kernel paging request at virtual address ffffff807ff2b000 Mem abort info: ESR = 0x96000006 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x06: level 2 translation fault Data abort info: ISV = 0, ISS = 0x00000006 CM = 0, WnR = 0 swapper pgtable: 4k pages, 39-bit VAs, pgdp=0000000081d87000 [ffffff807ff2b000] pgd=180000017fe18003, p4d=180000017fe18003, pud=180000017fe18003, pmd=0000000000000000 Internal error: Oops: 96000006 [#1] PREEMPT SMP Modules linked in: dm_integrity CPU: 7 PID: 21179 Comm: perf Not tainted 5.15.67-10882-ge4eb2eb988cd #1 baa443fb8e8477896a370b31a821eb2009f9bfba Hardware name: Google Lazor (rev3 - 8) (DT) pstate: a0400009 (NzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : __memcpy+0x110/0x260 lr : vread+0x194/0x294 sp : ffffffc013ee39d0 x29: ffffffc013ee39f0 x28: 0000000000001000 x27: ffffff807ff2b000 x26: 0000000000001000 x25: ffffffc0085a2000 x24: ffffff802d4b3000 x23: ffffff80f8a60000 x22: ffffff802d4b3000 x21: ffffffc0085a2000 x20: ffffff8080b7bc68 x19: 0000000000001000 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: ffffffd3073f2e60 x14: ffffffffad588000 x13: 0000000000000000 x12: 0000000000000001 x11: 00000000000001a2 x10: 00680000fff2bf0b x9 : 03fffffff807ff2b x8 : 0000000000000001 x7 : 0000000000000000 x6 : 0000000000000000 x5 : ffffff802d4b4000 x4 : ffffff807ff2c000 x3 : ffffffc013ee3a78 x2 : 0000000000001000 x1 : ffffff807ff2b000 x0 : ffffff802d4b3000 Call trace: __memcpy+0x110/0x260 read_kcore+0x584/0x778 proc_reg_read+0xb4/0xe4 During early boot, memblock reserves the pages for the ramoops reserved memory node in DT that would otherwise be part of the direct lowmem mapping. Pstore's ram backend reuses those reserved pages to change the memory type (writeback or non-cached) by passing the pages to vmap() (see pfn_to_page() usage in persistent_ram_vmap() for more details) with specific flags. When read_kcore() starts iterating over the vmalloc region, it runs over the virtual address that vmap() returned for ramoops. In aligned_vread() the virtual address is passed to vmalloc_to_page() which returns the page struct for the reserved lowmem area. That lowmem page is passed to kmap_atomic(), which effectively calls page_to_virt() that assumes a lowmem page struct must be directly accessible with __va() and friends. These pages are mapped via vmap() though, and the lowmem mapping was never made, so accessing them via the lowmem virtual address oopses like above. Let's side-step this problem by passing VM_IOREMAP to vmap(). This will tell vread() to not include the ramoops region in the kcore. Instead the area will look like a bunch of zeros. The alternative is to teach kmap() about vmalloc areas that intersect with lowmem. Presumably such a change isn't a one-liner, and there isn't much interest in inspecting the ramoops region in kcore files anyway, so the most expedient route is taken for now. Cc: Brian Geffon <bgeffon@google.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Fixes:404a604338
("staging: android: persistent_ram: handle reserving and mapping memory") Signed-off-by: Stephen Boyd <swboyd@chromium.org> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20221205233136.3420802-1-swboyd@chromium.org Signed-off-by: Sasha Levin <sashal@kernel.org>
601 lines
15 KiB
C
601 lines
15 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2012 Google, Inc.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/errno.h>
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#include <linux/init.h>
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#include <linux/io.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/memblock.h>
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#include <linux/pstore_ram.h>
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#include <linux/rslib.h>
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include <linux/vmalloc.h>
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#include <asm/page.h>
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/**
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* struct persistent_ram_buffer - persistent circular RAM buffer
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*
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* @sig:
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* signature to indicate header (PERSISTENT_RAM_SIG xor PRZ-type value)
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* @start:
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* offset into @data where the beginning of the stored bytes begin
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* @size:
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* number of valid bytes stored in @data
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*/
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struct persistent_ram_buffer {
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uint32_t sig;
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atomic_t start;
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atomic_t size;
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uint8_t data[0];
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};
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#define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
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static inline size_t buffer_size(struct persistent_ram_zone *prz)
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{
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return atomic_read(&prz->buffer->size);
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}
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static inline size_t buffer_start(struct persistent_ram_zone *prz)
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{
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return atomic_read(&prz->buffer->start);
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}
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/* increase and wrap the start pointer, returning the old value */
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static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
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{
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int old;
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int new;
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unsigned long flags = 0;
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if (!(prz->flags & PRZ_FLAG_NO_LOCK))
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raw_spin_lock_irqsave(&prz->buffer_lock, flags);
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old = atomic_read(&prz->buffer->start);
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new = old + a;
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while (unlikely(new >= prz->buffer_size))
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new -= prz->buffer_size;
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atomic_set(&prz->buffer->start, new);
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if (!(prz->flags & PRZ_FLAG_NO_LOCK))
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raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
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return old;
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}
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/* increase the size counter until it hits the max size */
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static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
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{
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size_t old;
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size_t new;
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unsigned long flags = 0;
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if (!(prz->flags & PRZ_FLAG_NO_LOCK))
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raw_spin_lock_irqsave(&prz->buffer_lock, flags);
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old = atomic_read(&prz->buffer->size);
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if (old == prz->buffer_size)
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goto exit;
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new = old + a;
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if (new > prz->buffer_size)
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new = prz->buffer_size;
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atomic_set(&prz->buffer->size, new);
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exit:
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if (!(prz->flags & PRZ_FLAG_NO_LOCK))
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raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
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}
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static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
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uint8_t *data, size_t len, uint8_t *ecc)
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{
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int i;
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/* Initialize the parity buffer */
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memset(prz->ecc_info.par, 0,
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prz->ecc_info.ecc_size * sizeof(prz->ecc_info.par[0]));
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encode_rs8(prz->rs_decoder, data, len, prz->ecc_info.par, 0);
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for (i = 0; i < prz->ecc_info.ecc_size; i++)
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ecc[i] = prz->ecc_info.par[i];
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}
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static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
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void *data, size_t len, uint8_t *ecc)
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{
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int i;
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for (i = 0; i < prz->ecc_info.ecc_size; i++)
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prz->ecc_info.par[i] = ecc[i];
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return decode_rs8(prz->rs_decoder, data, prz->ecc_info.par, len,
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NULL, 0, NULL, 0, NULL);
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}
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static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
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unsigned int start, unsigned int count)
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{
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struct persistent_ram_buffer *buffer = prz->buffer;
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uint8_t *buffer_end = buffer->data + prz->buffer_size;
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uint8_t *block;
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uint8_t *par;
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int ecc_block_size = prz->ecc_info.block_size;
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int ecc_size = prz->ecc_info.ecc_size;
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int size = ecc_block_size;
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if (!ecc_size)
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return;
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block = buffer->data + (start & ~(ecc_block_size - 1));
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par = prz->par_buffer + (start / ecc_block_size) * ecc_size;
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do {
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if (block + ecc_block_size > buffer_end)
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size = buffer_end - block;
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persistent_ram_encode_rs8(prz, block, size, par);
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block += ecc_block_size;
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par += ecc_size;
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} while (block < buffer->data + start + count);
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}
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static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
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{
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struct persistent_ram_buffer *buffer = prz->buffer;
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if (!prz->ecc_info.ecc_size)
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return;
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persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
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prz->par_header);
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}
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static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
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{
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struct persistent_ram_buffer *buffer = prz->buffer;
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uint8_t *block;
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uint8_t *par;
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if (!prz->ecc_info.ecc_size)
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return;
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block = buffer->data;
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par = prz->par_buffer;
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while (block < buffer->data + buffer_size(prz)) {
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int numerr;
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int size = prz->ecc_info.block_size;
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if (block + size > buffer->data + prz->buffer_size)
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size = buffer->data + prz->buffer_size - block;
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numerr = persistent_ram_decode_rs8(prz, block, size, par);
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if (numerr > 0) {
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pr_devel("error in block %p, %d\n", block, numerr);
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prz->corrected_bytes += numerr;
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} else if (numerr < 0) {
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pr_devel("uncorrectable error in block %p\n", block);
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prz->bad_blocks++;
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}
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block += prz->ecc_info.block_size;
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par += prz->ecc_info.ecc_size;
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}
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}
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static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
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struct persistent_ram_ecc_info *ecc_info)
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{
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int numerr;
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struct persistent_ram_buffer *buffer = prz->buffer;
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int ecc_blocks;
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size_t ecc_total;
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if (!ecc_info || !ecc_info->ecc_size)
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return 0;
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prz->ecc_info.block_size = ecc_info->block_size ?: 128;
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prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16;
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prz->ecc_info.symsize = ecc_info->symsize ?: 8;
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prz->ecc_info.poly = ecc_info->poly ?: 0x11d;
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ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size,
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prz->ecc_info.block_size +
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prz->ecc_info.ecc_size);
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ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size;
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if (ecc_total >= prz->buffer_size) {
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pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
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__func__, prz->ecc_info.ecc_size,
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ecc_total, prz->buffer_size);
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return -EINVAL;
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}
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prz->buffer_size -= ecc_total;
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prz->par_buffer = buffer->data + prz->buffer_size;
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prz->par_header = prz->par_buffer +
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ecc_blocks * prz->ecc_info.ecc_size;
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/*
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* first consecutive root is 0
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* primitive element to generate roots = 1
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*/
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prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly,
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0, 1, prz->ecc_info.ecc_size);
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if (prz->rs_decoder == NULL) {
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pr_info("init_rs failed\n");
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return -EINVAL;
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}
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/* allocate workspace instead of using stack VLA */
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prz->ecc_info.par = kmalloc_array(prz->ecc_info.ecc_size,
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sizeof(*prz->ecc_info.par),
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GFP_KERNEL);
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if (!prz->ecc_info.par) {
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pr_err("cannot allocate ECC parity workspace\n");
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return -ENOMEM;
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}
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prz->corrected_bytes = 0;
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prz->bad_blocks = 0;
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numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
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prz->par_header);
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if (numerr > 0) {
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pr_info("error in header, %d\n", numerr);
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prz->corrected_bytes += numerr;
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} else if (numerr < 0) {
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pr_info("uncorrectable error in header\n");
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prz->bad_blocks++;
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}
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return 0;
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}
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ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
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char *str, size_t len)
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{
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ssize_t ret;
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if (!prz->ecc_info.ecc_size)
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return 0;
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if (prz->corrected_bytes || prz->bad_blocks)
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ret = snprintf(str, len, ""
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"\n%d Corrected bytes, %d unrecoverable blocks\n",
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prz->corrected_bytes, prz->bad_blocks);
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else
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ret = snprintf(str, len, "\nNo errors detected\n");
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return ret;
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}
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static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
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const void *s, unsigned int start, unsigned int count)
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{
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struct persistent_ram_buffer *buffer = prz->buffer;
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memcpy_toio(buffer->data + start, s, count);
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persistent_ram_update_ecc(prz, start, count);
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}
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static int notrace persistent_ram_update_user(struct persistent_ram_zone *prz,
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const void __user *s, unsigned int start, unsigned int count)
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{
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struct persistent_ram_buffer *buffer = prz->buffer;
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int ret = unlikely(__copy_from_user(buffer->data + start, s, count)) ?
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-EFAULT : 0;
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persistent_ram_update_ecc(prz, start, count);
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return ret;
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}
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void persistent_ram_save_old(struct persistent_ram_zone *prz)
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{
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struct persistent_ram_buffer *buffer = prz->buffer;
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size_t size = buffer_size(prz);
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size_t start = buffer_start(prz);
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if (!size)
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return;
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if (!prz->old_log) {
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persistent_ram_ecc_old(prz);
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prz->old_log = kmalloc(size, GFP_KERNEL);
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}
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if (!prz->old_log) {
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pr_err("failed to allocate buffer\n");
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return;
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}
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prz->old_log_size = size;
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memcpy_fromio(prz->old_log, &buffer->data[start], size - start);
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memcpy_fromio(prz->old_log + size - start, &buffer->data[0], start);
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}
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int notrace persistent_ram_write(struct persistent_ram_zone *prz,
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const void *s, unsigned int count)
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{
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int rem;
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int c = count;
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size_t start;
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if (unlikely(c > prz->buffer_size)) {
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s += c - prz->buffer_size;
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c = prz->buffer_size;
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}
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buffer_size_add(prz, c);
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start = buffer_start_add(prz, c);
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rem = prz->buffer_size - start;
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if (unlikely(rem < c)) {
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persistent_ram_update(prz, s, start, rem);
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s += rem;
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c -= rem;
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start = 0;
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}
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persistent_ram_update(prz, s, start, c);
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persistent_ram_update_header_ecc(prz);
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return count;
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}
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int notrace persistent_ram_write_user(struct persistent_ram_zone *prz,
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const void __user *s, unsigned int count)
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{
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int rem, ret = 0, c = count;
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size_t start;
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if (unlikely(!access_ok(s, count)))
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return -EFAULT;
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if (unlikely(c > prz->buffer_size)) {
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s += c - prz->buffer_size;
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c = prz->buffer_size;
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}
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buffer_size_add(prz, c);
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start = buffer_start_add(prz, c);
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rem = prz->buffer_size - start;
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if (unlikely(rem < c)) {
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ret = persistent_ram_update_user(prz, s, start, rem);
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s += rem;
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c -= rem;
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start = 0;
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}
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if (likely(!ret))
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ret = persistent_ram_update_user(prz, s, start, c);
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persistent_ram_update_header_ecc(prz);
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return unlikely(ret) ? ret : count;
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}
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size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
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{
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return prz->old_log_size;
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}
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void *persistent_ram_old(struct persistent_ram_zone *prz)
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{
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return prz->old_log;
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}
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void persistent_ram_free_old(struct persistent_ram_zone *prz)
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{
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kfree(prz->old_log);
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prz->old_log = NULL;
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prz->old_log_size = 0;
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}
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void persistent_ram_zap(struct persistent_ram_zone *prz)
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{
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atomic_set(&prz->buffer->start, 0);
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atomic_set(&prz->buffer->size, 0);
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persistent_ram_update_header_ecc(prz);
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}
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static void *persistent_ram_vmap(phys_addr_t start, size_t size,
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unsigned int memtype)
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{
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struct page **pages;
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phys_addr_t page_start;
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unsigned int page_count;
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pgprot_t prot;
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unsigned int i;
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void *vaddr;
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page_start = start - offset_in_page(start);
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page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
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if (memtype)
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prot = pgprot_noncached(PAGE_KERNEL);
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else
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prot = pgprot_writecombine(PAGE_KERNEL);
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pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
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if (!pages) {
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pr_err("%s: Failed to allocate array for %u pages\n",
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__func__, page_count);
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return NULL;
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}
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for (i = 0; i < page_count; i++) {
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phys_addr_t addr = page_start + i * PAGE_SIZE;
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pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
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}
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/*
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* VM_IOREMAP used here to bypass this region during vread()
|
|
* and kmap_atomic() (i.e. kcore) to avoid __va() failures.
|
|
*/
|
|
vaddr = vmap(pages, page_count, VM_MAP | VM_IOREMAP, prot);
|
|
kfree(pages);
|
|
|
|
/*
|
|
* Since vmap() uses page granularity, we must add the offset
|
|
* into the page here, to get the byte granularity address
|
|
* into the mapping to represent the actual "start" location.
|
|
*/
|
|
return vaddr + offset_in_page(start);
|
|
}
|
|
|
|
static void *persistent_ram_iomap(phys_addr_t start, size_t size,
|
|
unsigned int memtype, char *label)
|
|
{
|
|
void *va;
|
|
|
|
if (!request_mem_region(start, size, label ?: "ramoops")) {
|
|
pr_err("request mem region (%s 0x%llx@0x%llx) failed\n",
|
|
label ?: "ramoops",
|
|
(unsigned long long)size, (unsigned long long)start);
|
|
return NULL;
|
|
}
|
|
|
|
if (memtype)
|
|
va = ioremap(start, size);
|
|
else
|
|
va = ioremap_wc(start, size);
|
|
|
|
/*
|
|
* Since request_mem_region() and ioremap() are byte-granularity
|
|
* there is no need handle anything special like we do when the
|
|
* vmap() case in persistent_ram_vmap() above.
|
|
*/
|
|
return va;
|
|
}
|
|
|
|
static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
|
|
struct persistent_ram_zone *prz, int memtype)
|
|
{
|
|
prz->paddr = start;
|
|
prz->size = size;
|
|
|
|
if (pfn_valid(start >> PAGE_SHIFT))
|
|
prz->vaddr = persistent_ram_vmap(start, size, memtype);
|
|
else
|
|
prz->vaddr = persistent_ram_iomap(start, size, memtype,
|
|
prz->label);
|
|
|
|
if (!prz->vaddr) {
|
|
pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
|
|
(unsigned long long)size, (unsigned long long)start);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
prz->buffer = prz->vaddr;
|
|
prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
|
|
struct persistent_ram_ecc_info *ecc_info)
|
|
{
|
|
int ret;
|
|
bool zap = !!(prz->flags & PRZ_FLAG_ZAP_OLD);
|
|
|
|
ret = persistent_ram_init_ecc(prz, ecc_info);
|
|
if (ret) {
|
|
pr_warn("ECC failed %s\n", prz->label);
|
|
return ret;
|
|
}
|
|
|
|
sig ^= PERSISTENT_RAM_SIG;
|
|
|
|
if (prz->buffer->sig == sig) {
|
|
if (buffer_size(prz) == 0) {
|
|
pr_debug("found existing empty buffer\n");
|
|
return 0;
|
|
}
|
|
|
|
if (buffer_size(prz) > prz->buffer_size ||
|
|
buffer_start(prz) > buffer_size(prz)) {
|
|
pr_info("found existing invalid buffer, size %zu, start %zu\n",
|
|
buffer_size(prz), buffer_start(prz));
|
|
zap = true;
|
|
} else {
|
|
pr_debug("found existing buffer, size %zu, start %zu\n",
|
|
buffer_size(prz), buffer_start(prz));
|
|
persistent_ram_save_old(prz);
|
|
}
|
|
} else {
|
|
pr_debug("no valid data in buffer (sig = 0x%08x)\n",
|
|
prz->buffer->sig);
|
|
prz->buffer->sig = sig;
|
|
zap = true;
|
|
}
|
|
|
|
/* Reset missing, invalid, or single-use memory area. */
|
|
if (zap)
|
|
persistent_ram_zap(prz);
|
|
|
|
return 0;
|
|
}
|
|
|
|
void persistent_ram_free(struct persistent_ram_zone *prz)
|
|
{
|
|
if (!prz)
|
|
return;
|
|
|
|
if (prz->vaddr) {
|
|
if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
|
|
/* We must vunmap() at page-granularity. */
|
|
vunmap(prz->vaddr - offset_in_page(prz->paddr));
|
|
} else {
|
|
iounmap(prz->vaddr);
|
|
release_mem_region(prz->paddr, prz->size);
|
|
}
|
|
prz->vaddr = NULL;
|
|
}
|
|
if (prz->rs_decoder) {
|
|
free_rs(prz->rs_decoder);
|
|
prz->rs_decoder = NULL;
|
|
}
|
|
kfree(prz->ecc_info.par);
|
|
prz->ecc_info.par = NULL;
|
|
|
|
persistent_ram_free_old(prz);
|
|
kfree(prz->label);
|
|
kfree(prz);
|
|
}
|
|
|
|
struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
|
|
u32 sig, struct persistent_ram_ecc_info *ecc_info,
|
|
unsigned int memtype, u32 flags, char *label)
|
|
{
|
|
struct persistent_ram_zone *prz;
|
|
int ret = -ENOMEM;
|
|
|
|
prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
|
|
if (!prz) {
|
|
pr_err("failed to allocate persistent ram zone\n");
|
|
goto err;
|
|
}
|
|
|
|
/* Initialize general buffer state. */
|
|
raw_spin_lock_init(&prz->buffer_lock);
|
|
prz->flags = flags;
|
|
prz->label = kstrdup(label, GFP_KERNEL);
|
|
|
|
ret = persistent_ram_buffer_map(start, size, prz, memtype);
|
|
if (ret)
|
|
goto err;
|
|
|
|
ret = persistent_ram_post_init(prz, sig, ecc_info);
|
|
if (ret)
|
|
goto err;
|
|
|
|
pr_debug("attached %s 0x%zx@0x%llx: %zu header, %zu data, %zu ecc (%d/%d)\n",
|
|
prz->label, prz->size, (unsigned long long)prz->paddr,
|
|
sizeof(*prz->buffer), prz->buffer_size,
|
|
prz->size - sizeof(*prz->buffer) - prz->buffer_size,
|
|
prz->ecc_info.ecc_size, prz->ecc_info.block_size);
|
|
|
|
return prz;
|
|
err:
|
|
persistent_ram_free(prz);
|
|
return ERR_PTR(ret);
|
|
}
|