Attachment 33133 Details for Bug 25678 – Patch: second take at allocating sparse memory maps

[patch] Patch: second take at allocating sparse memory maps

patch-libpciaccess-alpha-non-bwx-support-2.txt (text/plain), 3.59 KB, created by Michael Cree on 2010-02-06 15:56:02 UTC

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Creator: Michael Cree

Created: 2010-02-06 15:56:02 UTC

Size: 3.59 KB

patch

obsolete

>diff --git a/src/common_map.c b/src/common_map.c
>index 8757151..13f0afc 100644
>--- a/src/common_map.c
>+++ b/src/common_map.c
>@@ -51,5 +51,11 @@ _pci_hidden int
> pci_device_generic_unmap_range(struct pci_device *dev,
> 			       struct pci_device_mapping *map)
> {
>+#ifdef __alpha__
>+    if (map->pre_bwx && map->memory_sparse) {
>+	munmap(map->memory_sparse, map->size*(1<<5));
>+    }
>+#endif
>+
>     return (munmap(map->memory, map->size) == -1) ? errno : 0;
> }
>diff --git a/src/linux_sysfs.c b/src/linux_sysfs.c
>index 1832ee7..360dfe8 100644
>--- a/src/linux_sysfs.c
>+++ b/src/linux_sysfs.c
>@@ -548,10 +548,29 @@ pci_device_linux_sysfs_map_range(struct pci_device *dev,
>              map->region);
> 
>     fd = open(name, open_flags);
>+
>+#ifdef __alpha__
>+    map->pre_bwx = 0;
>+    map->memory_sparse = NULL;
>     if (fd == -1) {
>-        return errno;
>+	/* Attempt to map resourceX_dense which exists on non-BWX Alphas. */
>+	snprintf(name, 255, "%s/%04x:%02x:%02x.%1u/resource%u_dense",
>+		 SYS_BUS_PCI,
>+		 dev->domain,
>+		 dev->bus,
>+		 dev->dev,
>+		 dev->func,
>+		 map->region);
>+	fd = open(name, open_flags);
>+	if (fd != -1) {
>+	    map->pre_bwx = 1;
>+	}
>     }
>+#endif
> 
>+    if (fd == -1) {
>+	return errno;
>+    }
> 
>     map->memory = mmap(NULL, map->size, prot, MAP_SHARED, fd, offset);
>     if (map->memory == MAP_FAILED) {
>@@ -597,7 +616,60 @@ pci_device_linux_sysfs_map_range(struct pci_device *dev,
>     }
> #endif
> 
>-    close(fd);
>+#ifdef __alpha__
>+    /* The logic here for determining whether a sparse map is needed is not
>+     * ideal, but it's probably as good as we can do without extra
>+     * information from the caller telling us the intended use of the map.
>+     * If we don't allocate the map when it is needed then segmentation
>+     * violations are possible downstream; if we allocate the map when it is
>+     * not needed then we waste valuable page table entries.  The intent is
>+     * to err slightly on the side of allocating the sparse map.
>+     */
>+
>+    if (map->pre_bwx && (dev->regions[map->region].is_IO || map->size <= 131072)) {
>+	/* We map sparse for IO and small memory mappings.  This map is only
>+	 * needed when byte or word read/writes are made to IO ports.
>+	 */
>+	close(fd);
>+
>+	snprintf(name, 255, "%s/%04x:%02x:%02x.%1u/resource%u_sparse",
>+		 SYS_BUS_PCI,
>+		 dev->domain,
>+		 dev->bus,
>+		 dev->dev,
>+		 dev->func,
>+		 map->region);
>+	fd = open(name, open_flags);
>+	if (fd == -1 && dev->regions[map->region].is_IO) {
>+	    /* If this is an IO map we fail -- any attempt at a byte or word
>+	     * access to the dense mapping is likely to result in
>+	     * unpredictable behaviour.
>+	     */
>+	    int saved_errno = errno;
>+	    map->memory_sparse = NULL;
>+	    pci_device_generic_unmap_range(dev, map);
>+	    return saved_errno;
>+	}
>+
>+	/* But if a memory map doesn't have a sparse resource we continue
>+	 *  without the sparse map -- maybe it's not MMIO anyway.
>+	 */
>+	if (fd != -1) {
>+	    map->memory_sparse = mmap(NULL, map->size*(1<<5), prot,
>+				      MAP_SHARED, fd, offset*(1<<5));
>+	    if (map->memory_sparse == MAP_FAILED) {
>+		int saved_errno = errno;
>+		map->memory_sparse = NULL;
>+		pci_device_generic_unmap_range(dev, map);
>+		close(fd);
>+		return saved_errno;
>+	    }
>+	}
>+    }
>+#endif
>+
>+    if (fd != -1)
>+	close(fd);
> 
>     return 0;
> }
>diff --git a/src/pciaccess_private.h b/src/pciaccess_private.h
>index 77eb57b..e0828f6 100644
>--- a/src/pciaccess_private.h
>+++ b/src/pciaccess_private.h
>@@ -85,6 +85,10 @@ struct pci_device_mapping {
>     unsigned region;
>     unsigned flags;
>     void *memory;
>+#ifdef __alpha__
>+    void *memory_sparse;
>+    int pre_bwx;
>+#endif
> };
> 
> struct pci_io_handle {

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Attachments on bug 25678: 32126 | 32127 | 32128 | 32129 | 32130 | 33098 | 33100 | 33101 | 33124 | 33133 | 33140 | 33141

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