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| 1 | +// SPDX-License-Identifier: GPL-2.0 |
| 2 | + |
| 3 | +#include <linux/efi.h> |
| 4 | +#include <linux/init.h> |
| 5 | +#include <linux/io.h> |
| 6 | +#include <linux/kernel.h> |
| 7 | +#include <linux/kobject.h> |
| 8 | +#include <linux/module.h> |
| 9 | +#include <linux/platform_device.h> |
| 10 | +#include <linux/sysfs.h> |
| 11 | + |
| 12 | +#define OVMF_DEBUG_LOG_MAGIC1 0x3167646d666d766f // "ovmfmdg1" |
| 13 | +#define OVMF_DEBUG_LOG_MAGIC2 0x3267646d666d766f // "ovmfmdg2" |
| 14 | + |
| 15 | +struct ovmf_debug_log_header { |
| 16 | + u64 magic1; |
| 17 | + u64 magic2; |
| 18 | + u64 hdr_size; |
| 19 | + u64 log_size; |
| 20 | + u64 lock; // edk2 spinlock |
| 21 | + u64 head_off; |
| 22 | + u64 tail_off; |
| 23 | + u64 truncated; |
| 24 | + u8 fw_version[128]; |
| 25 | +}; |
| 26 | + |
| 27 | +static struct ovmf_debug_log_header *hdr; |
| 28 | +static u8 *logbuf; |
| 29 | +static u64 logbufsize; |
| 30 | + |
| 31 | +static ssize_t ovmf_log_read(struct file *filp, struct kobject *kobj, |
| 32 | + const struct bin_attribute *attr, char *buf, |
| 33 | + loff_t offset, size_t count) |
| 34 | +{ |
| 35 | + u64 start, end; |
| 36 | + |
| 37 | + start = hdr->head_off + offset; |
| 38 | + if (hdr->head_off > hdr->tail_off && start >= hdr->log_size) |
| 39 | + start -= hdr->log_size; |
| 40 | + |
| 41 | + end = start + count; |
| 42 | + if (start > hdr->tail_off) { |
| 43 | + if (end > hdr->log_size) |
| 44 | + end = hdr->log_size; |
| 45 | + } else { |
| 46 | + if (end > hdr->tail_off) |
| 47 | + end = hdr->tail_off; |
| 48 | + } |
| 49 | + |
| 50 | + if (start > logbufsize || end > logbufsize) |
| 51 | + return 0; |
| 52 | + if (start >= end) |
| 53 | + return 0; |
| 54 | + |
| 55 | + memcpy(buf, logbuf + start, end - start); |
| 56 | + return end - start; |
| 57 | +} |
| 58 | + |
| 59 | +static struct bin_attribute ovmf_log_bin_attr = { |
| 60 | + .attr = { |
| 61 | + .name = "ovmf_debug_log", |
| 62 | + .mode = 0444, |
| 63 | + }, |
| 64 | + .read = ovmf_log_read, |
| 65 | +}; |
| 66 | + |
| 67 | +int __init ovmf_log_probe(unsigned long ovmf_debug_log_table) |
| 68 | +{ |
| 69 | + int ret = -EINVAL; |
| 70 | + u64 size; |
| 71 | + |
| 72 | + /* map + verify header */ |
| 73 | + hdr = memremap(ovmf_debug_log_table, sizeof(*hdr), MEMREMAP_WB); |
| 74 | + if (!hdr) { |
| 75 | + pr_err("OVMF debug log: header map failed\n"); |
| 76 | + return -EINVAL; |
| 77 | + } |
| 78 | + |
| 79 | + if (hdr->magic1 != OVMF_DEBUG_LOG_MAGIC1 || |
| 80 | + hdr->magic2 != OVMF_DEBUG_LOG_MAGIC2) { |
| 81 | + printk(KERN_ERR "OVMF debug log: magic mismatch\n"); |
| 82 | + goto err_unmap; |
| 83 | + } |
| 84 | + |
| 85 | + size = hdr->hdr_size + hdr->log_size; |
| 86 | + pr_info("OVMF debug log: firmware version: \"%s\"\n", hdr->fw_version); |
| 87 | + pr_info("OVMF debug log: buffer size: %lluk\n", size / 1024); |
| 88 | + |
| 89 | + /* map complete log buffer */ |
| 90 | + memunmap(hdr); |
| 91 | + hdr = memremap(ovmf_debug_log_table, size, MEMREMAP_WB); |
| 92 | + if (!hdr) { |
| 93 | + pr_err("OVMF debug log: buffer map failed\n"); |
| 94 | + return -EINVAL; |
| 95 | + } |
| 96 | + logbuf = (void *)hdr + hdr->hdr_size; |
| 97 | + logbufsize = hdr->log_size; |
| 98 | + |
| 99 | + ovmf_log_bin_attr.size = size; |
| 100 | + ret = sysfs_create_bin_file(efi_kobj, &ovmf_log_bin_attr); |
| 101 | + if (ret != 0) { |
| 102 | + pr_err("OVMF debug log: sysfs register failed\n"); |
| 103 | + goto err_unmap; |
| 104 | + } |
| 105 | + |
| 106 | + return 0; |
| 107 | + |
| 108 | +err_unmap: |
| 109 | + memunmap(hdr); |
| 110 | + return ret; |
| 111 | +} |
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