linux-kernel - radeon: RFC speed cap detection on ppc64

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <50819140.8030806@linux.vnet.ibm.com>
Date:	Fri, 19 Oct 2012 14:43:28 -0300
From:	Lucas Kannebley Tavares <lucaskt@...ux.vnet.ibm.com>
To:	dri-devel@...ts.freedesktop.org
CC:	David Airlie <airlied@...ux.ie>,
	Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Brian King <brking@...ux.vnet.ibm.com>,
	Benjamin Herrenschmidt <benh@....ibm.com>,
	Nishanth Aravamudan <nacc@...ux.vnet.ibm.com>
Subject: radeon: RFC speed cap detection on ppc64

The radeon driver does speed cap detection on the root PCI device for 
the maximum speed with which the adapter can communicate. On ppc64 
systems, however, the root device belongs to the Hypervisor, so the 
current code would case a null pointer dereference.

I propose to look for the outmost bus with a parent node and get speed 
caps from it, though I suppose the cleaner way would be to inspect all 
devices along the way and choose the smallest speed cap.

Does anyone have suggestions for this?

Thanks

--
--- 
/home/lucaskt/work/devdrivers/kernel/linux/drivers/gpu/drm/drm_pci.c 
2012-09-26 10:06:00.280549928 -0300
+++ drm_pci.c	2012-09-26 15:38:51.121786353 -0300
@@ -466,6 +466,19 @@
  }
  EXPORT_SYMBOL(drm_pci_exit);

+static struct pci_dev *drm_get_pcie_root_dev(struct pci_dev *dev)
+{
+	// Go up through all possible busses to get the info for the outmost bus
+	while (!pci_is_root_bus(dev->bus))
+		dev = dev->bus->parent->self;
+	
+	// In POWER architectures there's no PCI root device, so it should 
just read
+	// the caps from the device itself
+	if (dev->bus->self != NULL)
+		return dev->bus->self;
+	else
+		return dev;
+}
+
  int drm_pcie_get_speed_cap_mask(struct drm_device *dev, u32 *mask)
  {
  	struct pci_dev *root;
@@ -479,7 +492,7 @@
  	if (!pci_is_pcie(dev->pdev))
  		return -EINVAL;

-	root = dev->pdev->bus->self;
+	root = drm_get_pcie_root_dev(dev->pdev);

  	pos = pci_pcie_cap(root);
  	if (!pos)


-- 
Lucas Kannebley Tavares
Software Engineer
IBM Linux Technology Center

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/