[PATCH v3] PCI: Use ioremap(), not phys_to_virt() for platform ROM

[Mikel Rychliski <mikel@mikelr.com>]

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 updating all drivers which can access a platform
provided ROM. Instead of calling the helper function pci_platform_rom()
which uses phys_to_virt(), call ioremap() directly on the pdev->rom.

radeon_read_platform_bios() previously directly accessed an __iomem
pointer. Avoid this by calling memcpy_fromio() instead of kmemdup().

pci_platform_rom() now has no remaining callers, so remove it.

Signed-off-by: Mikel Rychliski <mikel@mikelr.com>
---

Tested on a MacPro 1,1 with a Radeon X1900 XT card and 32-bit kernel.

Changes in v3:
 - Inline pci_platform_rom()

Changes in v2:
 - Add iounmap() call in nouveau
 - Update function comment for pci_platform_rom()
 - Minor changes to commit messages

 drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c           | 31 +++++++++++++---------
 .../gpu/drm/nouveau/nvkm/subdev/bios/shadowpci.c   | 17 ++++++++++--
 drivers/gpu/drm/radeon/radeon_bios.c               | 30 +++++++++++++--------
 drivers/pci/rom.c                                  | 17 ------------
 include/linux/pci.h                                |  1 -
 5 files changed, 52 insertions(+), 44 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c
index 50dff69a0f6e..b1172d93c99c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c
@@ -192,30 +192,35 @@ static bool amdgpu_read_bios_from_rom(struct amdgpu_device *adev)
 
 static bool amdgpu_read_platform_bios(struct amdgpu_device *adev)
 {
-	uint8_t __iomem *bios;
-	size_t size;
+	phys_addr_t rom = adev->pdev->rom;
+	size_t romlen = adev->pdev->romlen;
+	void __iomem *bios;
 
 	adev->bios = NULL;
 
-	bios = pci_platform_rom(adev->pdev, &size);
-	if (!bios) {
+	if (!rom || romlen == 0)
 		return false;
-	}
 
-	adev->bios = kzalloc(size, GFP_KERNEL);
-	if (adev->bios == NULL)
+	adev->bios = kzalloc(romlen, GFP_KERNEL);
+	if (!adev->bios)
 		return false;
 
-	memcpy_fromio(adev->bios, bios, size);
+	bios = ioremap(rom, romlen);
+	if (!bios)
+		goto free_bios;
 
-	if (!check_atom_bios(adev->bios, size)) {
-		kfree(adev->bios);
-		return false;
-	}
+	memcpy_fromio(adev->bios, bios, romlen);
+	iounmap(bios);
 
-	adev->bios_size = size;
+	if (!check_atom_bios(adev->bios, romlen))
+		goto free_bios;
+
+	adev->bios_size = romlen;
 
 	return true;
+free_bios:
+	kfree(adev->bios);
+	return false;
 }
 
 #ifdef CONFIG_ACPI
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/shadowpci.c b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/shadowpci.c
index 9b91da09dc5f..8d9812a51ef6 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/bios/shadowpci.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/bios/shadowpci.c
@@ -101,9 +101,13 @@ platform_init(struct nvkm_bios *bios, const char *name)
 	else
 		return ERR_PTR(-ENODEV);
 
+	if (!pdev->rom || pdev->romlen == 0)
+		return ERR_PTR(-ENODEV);
+
 	if ((priv = kmalloc(sizeof(*priv), GFP_KERNEL))) {
+		priv->size = pdev->romlen;
 		if (ret = -ENODEV,
-		    (priv->rom = pci_platform_rom(pdev, &priv->size)))
+		    (priv->rom = ioremap(pdev->rom, pdev->romlen)))
 			return priv;
 		kfree(priv);
 	}
@@ -111,11 +115,20 @@ platform_init(struct nvkm_bios *bios, const char *name)
 	return ERR_PTR(ret);
 }
 
+static void
+platform_fini(void *data)
+{
+	struct priv *priv = data;
+
+	iounmap(priv->rom);
+	kfree(priv);
+}
+
 const struct nvbios_source
 nvbios_platform = {
 	.name = "PLATFORM",
 	.init = platform_init,
-	.fini = (void(*)(void *))kfree,
+	.fini = platform_fini,
 	.read = pcirom_read,
 	.rw = true,
 };
diff --git a/drivers/gpu/drm/radeon/radeon_bios.c b/drivers/gpu/drm/radeon/radeon_bios.c
index c42f73fad3e3..bb29cf02974d 100644
--- a/drivers/gpu/drm/radeon/radeon_bios.c
+++ b/drivers/gpu/drm/radeon/radeon_bios.c
@@ -108,25 +108,33 @@ static bool radeon_read_bios(struct radeon_device *rdev)
 
 static bool radeon_read_platform_bios(struct radeon_device *rdev)
 {
-	uint8_t __iomem *bios;
-	size_t size;
+	phys_addr_t rom = rdev->pdev->rom;
+	size_t romlen = rdev->pdev->romlen;
+	void __iomem *bios;
 
 	rdev->bios = NULL;
 
-	bios = pci_platform_rom(rdev->pdev, &size);
-	if (!bios) {
+	if (!rom || romlen == 0)
 		return false;
-	}
 
-	if (size == 0 || bios[0] != 0x55 || bios[1] != 0xaa) {
+	rdev->bios = kzalloc(romlen, GFP_KERNEL);
+	if (!rdev->bios)
 		return false;
-	}
-	rdev->bios = kmemdup(bios, size, GFP_KERNEL);
-	if (rdev->bios == NULL) {
-		return false;
-	}
+
+	bios = ioremap(rom, romlen);
+	if (!bios)
+		goto free_bios;
+
+	memcpy_fromio(rdev->bios, bios, romlen);
+	iounmap(bios);
+
+	if (rdev->bios[0] != 0x55 || rdev->bios[1] != 0xaa)
+		goto free_bios;
 
 	return true;
+free_bios:
+	kfree(rdev->bios);
+	return false;
 }
 
 #ifdef CONFIG_ACPI
diff --git a/drivers/pci/rom.c b/drivers/pci/rom.c
index 137bf0cee897..8fc9a4e911e3 100644
--- a/drivers/pci/rom.c
+++ b/drivers/pci/rom.c
@@ -195,20 +195,3 @@ void pci_unmap_rom(struct pci_dev *pdev, void __iomem *rom)
 		pci_disable_rom(pdev);
 }
 EXPORT_SYMBOL(pci_unmap_rom);
-
-/**
- * pci_platform_rom - provides a pointer to any ROM image provided by the
- * platform
- * @pdev: pointer to pci device struct
- * @size: pointer to receive size of pci window over ROM
- */
-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 NULL;
-}
-EXPORT_SYMBOL(pci_platform_rom);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 3840a541a9de..7268dcf1f23e 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1214,7 +1214,6 @@ int pci_enable_rom(struct pci_dev *pdev);
 void pci_disable_rom(struct pci_dev *pdev);
 void __iomem __must_check *pci_map_rom(struct pci_dev *pdev, size_t *size);
 void pci_unmap_rom(struct pci_dev *pdev, void __iomem *rom);
-void __iomem __must_check *pci_platform_rom(struct pci_dev *pdev, size_t *size);
 
 /* Power management related routines */
 int pci_save_state(struct pci_dev *dev);
-- 
2.13.7

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