[PATCH 3/11] ACPI: Fix acpi_os_read_memory() and acpi_os_write_memory()
From: Rafael J. Wysocki <hidden>
Date: 2011-01-20 11:30:09
From: Rafael J. Wysocki <redacted> The functions acpi_os_read_memory() and acpi_os_write_memory() do two wrong things. First, they shouldn't call rcu_read_unlock() before the looked up address is actually used for I/O, because in that case the mapping it belongs to may be removed before the I/O is done. Second, they shouldn't use the physical address if there's no mapping for it, because that may lead to problems (at least for the "write" case it's like sending data to a random physical address in the hope it's going to work). Make the rcu_read_unlock() be called by these functions when the I/O is complete and modify them to dump stack and return error code if the requested physical address is not present in the ACPI iomaps. Signed-off-by: Rafael J. Wysocki <redacted> --- drivers/acpi/osl.c | 31 +++++++++++++------------------ 1 file changed, 13 insertions(+), 18 deletions(-) Index: linux-2.6/drivers/acpi/osl.c ===================================================================
--- linux-2.6.orig/drivers/acpi/osl.c
+++ linux-2.6/drivers/acpi/osl.c@@ -638,17 +638,17 @@ acpi_os_read_memory(acpi_physical_addres { u32 dummy; void __iomem *virt_addr; - int size = width / 8, unmap = 0; + + if (!value) + value = &dummy; rcu_read_lock(); - virt_addr = acpi_map_vaddr_lookup(phys_addr, size); - rcu_read_unlock(); + virt_addr = acpi_map_vaddr_lookup(phys_addr, width / 8); if (!virt_addr) { - virt_addr = acpi_os_ioremap(phys_addr, size); - unmap = 1; + rcu_read_unlock(); + WARN(true, "Address not mapped: %llx\n", phys_addr); + return AE_BAD_ADDRESS; } - if (!value) - value = &dummy; switch (width) { case 8:
@@ -663,9 +663,7 @@ acpi_os_read_memory(acpi_physical_addres default: BUG(); } - - if (unmap) - iounmap(virt_addr); + rcu_read_unlock(); return AE_OK; }
@@ -674,14 +672,13 @@ acpi_status acpi_os_write_memory(acpi_physical_address phys_addr, u32 value, u32 width) { void __iomem *virt_addr; - int size = width / 8, unmap = 0; rcu_read_lock(); - virt_addr = acpi_map_vaddr_lookup(phys_addr, size); - rcu_read_unlock(); + virt_addr = acpi_map_vaddr_lookup(phys_addr, width / 8); if (!virt_addr) { - virt_addr = acpi_os_ioremap(phys_addr, size); - unmap = 1; + rcu_read_unlock(); + WARN(true, "Address not mapped: %llx\n", phys_addr); + return AE_BAD_ADDRESS; } switch (width) {
@@ -697,9 +694,7 @@ acpi_os_write_memory(acpi_physical_addre default: BUG(); } - - if (unmap) - iounmap(virt_addr); + rcu_read_unlock(); return AE_OK; }