https://github.com/torvalds/linux
Tip revision: 88603b6dc419445847923fcb7fe5080067a30f98 authored by Linus Torvalds on 01 January 2023, 21:53:16 UTC
Linux 6.2-rc2
Linux 6.2-rc2
Tip revision: 88603b6
probe_roms.c
// SPDX-License-Identifier: GPL-2.0
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/uaccess.h>
#include <linux/mmzone.h>
#include <linux/ioport.h>
#include <linux/seq_file.h>
#include <linux/console.h>
#include <linux/init.h>
#include <linux/edd.h>
#include <linux/dmi.h>
#include <linux/pfn.h>
#include <linux/pci.h>
#include <linux/export.h>
#include <asm/probe_roms.h>
#include <asm/pci-direct.h>
#include <asm/e820/api.h>
#include <asm/mmzone.h>
#include <asm/setup.h>
#include <asm/sections.h>
#include <asm/io.h>
#include <asm/setup_arch.h>
#include <asm/sev.h>
static struct resource system_rom_resource = {
.name = "System ROM",
.start = 0xf0000,
.end = 0xfffff,
.flags = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
};
static struct resource extension_rom_resource = {
.name = "Extension ROM",
.start = 0xe0000,
.end = 0xeffff,
.flags = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
};
static struct resource adapter_rom_resources[] = { {
.name = "Adapter ROM",
.start = 0xc8000,
.end = 0,
.flags = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
.name = "Adapter ROM",
.start = 0,
.end = 0,
.flags = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
.name = "Adapter ROM",
.start = 0,
.end = 0,
.flags = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
.name = "Adapter ROM",
.start = 0,
.end = 0,
.flags = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
.name = "Adapter ROM",
.start = 0,
.end = 0,
.flags = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
}, {
.name = "Adapter ROM",
.start = 0,
.end = 0,
.flags = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
} };
static struct resource video_rom_resource = {
.name = "Video ROM",
.start = 0xc0000,
.end = 0xc7fff,
.flags = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
};
/* does this oprom support the given pci device, or any of the devices
* that the driver supports?
*/
static bool match_id(struct pci_dev *pdev, unsigned short vendor, unsigned short device)
{
struct pci_driver *drv = to_pci_driver(pdev->dev.driver);
const struct pci_device_id *id;
if (pdev->vendor == vendor && pdev->device == device)
return true;
for (id = drv ? drv->id_table : NULL; id && id->vendor; id++)
if (id->vendor == vendor && id->device == device)
break;
return id && id->vendor;
}
static bool probe_list(struct pci_dev *pdev, unsigned short vendor,
const void *rom_list)
{
unsigned short device;
do {
if (get_kernel_nofault(device, rom_list) != 0)
device = 0;
if (device && match_id(pdev, vendor, device))
break;
rom_list += 2;
} while (device);
return !!device;
}
static struct resource *find_oprom(struct pci_dev *pdev)
{
struct resource *oprom = NULL;
int i;
for (i = 0; i < ARRAY_SIZE(adapter_rom_resources); i++) {
struct resource *res = &adapter_rom_resources[i];
unsigned short offset, vendor, device, list, rev;
const void *rom;
if (res->end == 0)
break;
rom = isa_bus_to_virt(res->start);
if (get_kernel_nofault(offset, rom + 0x18) != 0)
continue;
if (get_kernel_nofault(vendor, rom + offset + 0x4) != 0)
continue;
if (get_kernel_nofault(device, rom + offset + 0x6) != 0)
continue;
if (match_id(pdev, vendor, device)) {
oprom = res;
break;
}
if (get_kernel_nofault(list, rom + offset + 0x8) == 0 &&
get_kernel_nofault(rev, rom + offset + 0xc) == 0 &&
rev >= 3 && list &&
probe_list(pdev, vendor, rom + offset + list)) {
oprom = res;
break;
}
}
return oprom;
}
void __iomem *pci_map_biosrom(struct pci_dev *pdev)
{
struct resource *oprom = find_oprom(pdev);
if (!oprom)
return NULL;
return ioremap(oprom->start, resource_size(oprom));
}
EXPORT_SYMBOL(pci_map_biosrom);
void pci_unmap_biosrom(void __iomem *image)
{
iounmap(image);
}
EXPORT_SYMBOL(pci_unmap_biosrom);
size_t pci_biosrom_size(struct pci_dev *pdev)
{
struct resource *oprom = find_oprom(pdev);
return oprom ? resource_size(oprom) : 0;
}
EXPORT_SYMBOL(pci_biosrom_size);
#define ROMSIGNATURE 0xaa55
static int __init romsignature(const unsigned char *rom)
{
const unsigned short * const ptr = (const unsigned short *)rom;
unsigned short sig;
return get_kernel_nofault(sig, ptr) == 0 && sig == ROMSIGNATURE;
}
static int __init romchecksum(const unsigned char *rom, unsigned long length)
{
unsigned char sum, c;
for (sum = 0; length && get_kernel_nofault(c, rom++) == 0; length--)
sum += c;
return !length && !sum;
}
void __init probe_roms(void)
{
unsigned long start, length, upper;
const unsigned char *rom;
unsigned char c;
int i;
/*
* The ROM memory range is not part of the e820 table and is therefore not
* pre-validated by BIOS. The kernel page table maps the ROM region as encrypted
* memory, and SNP requires encrypted memory to be validated before access.
* Do that here.
*/
snp_prep_memory(video_rom_resource.start,
((system_rom_resource.end + 1) - video_rom_resource.start),
SNP_PAGE_STATE_PRIVATE);
/* video rom */
upper = adapter_rom_resources[0].start;
for (start = video_rom_resource.start; start < upper; start += 2048) {
rom = isa_bus_to_virt(start);
if (!romsignature(rom))
continue;
video_rom_resource.start = start;
if (get_kernel_nofault(c, rom + 2) != 0)
continue;
/* 0 < length <= 0x7f * 512, historically */
length = c * 512;
/* if checksum okay, trust length byte */
if (length && romchecksum(rom, length))
video_rom_resource.end = start + length - 1;
request_resource(&iomem_resource, &video_rom_resource);
break;
}
start = (video_rom_resource.end + 1 + 2047) & ~2047UL;
if (start < upper)
start = upper;
/* system rom */
request_resource(&iomem_resource, &system_rom_resource);
upper = system_rom_resource.start;
/* check for extension rom (ignore length byte!) */
rom = isa_bus_to_virt(extension_rom_resource.start);
if (romsignature(rom)) {
length = resource_size(&extension_rom_resource);
if (romchecksum(rom, length)) {
request_resource(&iomem_resource, &extension_rom_resource);
upper = extension_rom_resource.start;
}
}
/* check for adapter roms on 2k boundaries */
for (i = 0; i < ARRAY_SIZE(adapter_rom_resources) && start < upper; start += 2048) {
rom = isa_bus_to_virt(start);
if (!romsignature(rom))
continue;
if (get_kernel_nofault(c, rom + 2) != 0)
continue;
/* 0 < length <= 0x7f * 512, historically */
length = c * 512;
/* but accept any length that fits if checksum okay */
if (!length || start + length > upper || !romchecksum(rom, length))
continue;
adapter_rom_resources[i].start = start;
adapter_rom_resources[i].end = start + length - 1;
request_resource(&iomem_resource, &adapter_rom_resources[i]);
start = adapter_rom_resources[i++].end & ~2047UL;
}
}