[PATCH 2/4] PCI: Use ioremap, not phys_to_virt for platform rom

[Mikel Rychliski]

On some EFI systems, the video BIOS is provided by the EFI firmware.  The
boot stub code stores the physical address of the ROM image in pdev->rom.
Currently we attempt to access this pointer using phys_to_virt, which
doesn't work with CONFIG_HIGHMEM.

On these systems, attempting to load the radeon module on a x86_32 kernel
can result in the following:

    BUG: unable to handle page fault for address: 3e8ed03c
    #PF: supervisor read access in kernel mode
    #PF: error_code(0x0000) - not-present page
    *pde = 00000000
    Oops: 0000 [#1] PREEMPT SMP
    CPU: 0 PID: 317 Comm: systemd-udevd Not tainted 5.6.0-rc3-next-20200228 #2
    Hardware name: Apple Computer, Inc. MacPro1,1/Mac-F4208DC8, BIOS     MP11.88Z.005C.B08.0707021221 07/02/07
    EIP: radeon_get_bios+0x5ed/0xe50 [radeon]
    Code: 00 00 84 c0 0f 85 12 fd ff ff c7 87 64 01 00 00 00 00 00 00 8b 47 08 8b 55 b0 e8 1e 83 e1 d6 85 c0 74 1a 8b 55 c0 85 d2 74 13 <80> 38 55 75 0e 80 78 01 aa 0f 84 a4 03 00 00 8d 74 26 00 68 dc 06
    EAX: 3e8ed03c EBX: 00000000 ECX: 3e8ed03c EDX: 00010000
    ESI: 00040000 EDI: eec04000 EBP: eef3fc60 ESP: eef3fbe0
    DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 EFLAGS: 00010206
    CR0: 80050033 CR2: 3e8ed03c CR3: 2ec77000 CR4: 000006d0
    Call Trace:
     ? register_client+0x34/0xe0
     ? register_client+0xab/0xe0
     r520_init+0x26/0x240 [radeon]
     radeon_device_init+0x533/0xa50 [radeon]
     radeon_driver_load_kms+0x80/0x220 [radeon]
     drm_dev_register+0xa7/0x180 [drm]
     radeon_pci_probe+0x10f/0x1a0 [radeon]
     pci_device_probe+0xd4/0x140
     really_probe+0x13d/0x3b0
     driver_probe_device+0x56/0xd0
     device_driver_attach+0x49/0x50
     __driver_attach+0x79/0x130
     ? device_driver_attach+0x50/0x50
     bus_for_each_dev+0x5b/0xa0
     driver_attach+0x19/0x20
     ? device_driver_attach+0x50/0x50
     bus_add_driver+0x117/0x1d0
     ? pci_bus_num_vf+0x20/0x20
     driver_register+0x66/0xb0
     ? 0xf80f4000
     __pci_register_driver+0x3d/0x40
     radeon_init+0x82/0x1000 [radeon]
     do_one_initcall+0x42/0x200
     ? kvfree+0x25/0x30
     ? __vunmap+0x206/0x230
     ? kmem_cache_alloc_trace+0x16f/0x220
     ? do_init_module+0x21/0x220
     do_init_module+0x50/0x220
     load_module+0x1f26/0x2200
     sys_init_module+0x12d/0x160
     do_fast_syscall_32+0x82/0x250
     entry_SYSENTER_32+0xa5/0xf8

Fix the issue by using ioremap instead of phys_to_virt in pci_platform_rom.

Signed-off-by: Mikel Rychliski <mikel at mikelr.com>
---
 drivers/pci/rom.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/rom.c b/drivers/pci/rom.c
index 137bf0cee897..e352798eed0c 100644
--- a/drivers/pci/rom.c
+++ b/drivers/pci/rom.c
@@ -197,8 +197,7 @@ void pci_unmap_rom(struct pci_dev *pdev, void __iomem *rom)
 EXPORT_SYMBOL(pci_unmap_rom);
 
 /**
- * pci_platform_rom - provides a pointer to any ROM image provided by the
- * platform
+ * pci_platform_rom - ioremap the ROM image provided by the platform
  * @pdev: pointer to pci device struct
  * @size: pointer to receive size of pci window over ROM
  */
@@ -206,7 +205,7 @@ void __iomem *pci_platform_rom(struct pci_dev *pdev, size_t *size)
 {
 	if (pdev->rom && pdev->romlen) {
 		*size = pdev->romlen;
-		return phys_to_virt((phys_addr_t)pdev->rom);
+		return ioremap(pdev->rom, pdev->romlen);
 	}
 
 	return NULL;
-- 
2.13.7