aperture_64.c: duplicated code, buggy?

Hi!

void __init early_gart_iommu_check(void)

contains

	for (num = 24; num < 32; num++) {
		if (!early_is_k8_nb(read_pci_config(0, num, 3, 0x00)))
			continue;

loop, with very similar loop duplicated in

void __init gart_iommu_hole_init(void)

. First copy of a loop seems to be buggy, too. It uses 0 as a "nothing
set" value, which may actually bite us in last_aper_enabled case
(because it may be often zero).

(Beware, it is hard to test this patch, because this code has about
2^8 different code paths, depending on hardware and cmdline settings).

Plus, the second loop does not check for consistency of
aper_enabled. Should it?

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/kernel/aperture_64.c b/arch/x86/kernel/aperture_64.c
index 6eea42e..e5b17f9 100644 (file)
--- a/arch/x86/kernel/aperture_64.c
+++ b/arch/x86/kernel/aperture_64.c
@@ -271,16 +271,16 @@ void __init early_gart_iommu_check(void)
         * or BIOS forget to put that in reserved.
         * try to update e820 to make that region as reserved.
         */
-       int fix, slot;
+       int i, fix, slot;
        u32 ctl;
        u32 aper_size = 0, aper_order = 0, last_aper_order = 0;
        u64 aper_base = 0, last_aper_base = 0;
-       int aper_enabled = 0, last_aper_enabled = 0;
-       int i;
+       int aper_enabled = 0, last_aper_enabled = 0, last_valid = 0;
 
        if (!early_pci_allowed())
                return;
 
+       /* This is mostly duplicate of iommu_hole_init */
        fix = 0;
        for (i = 0; i < ARRAY_SIZE(bus_dev_ranges); i++) {
                int bus;
@@ -301,19 +301,22 @@ void __init early_gart_iommu_check(void)
                        aper_base = read_pci_config(bus, slot, 3, AMD64_GARTAPERTUREBASE) & 0x7fff;
                        aper_base <<= 25;
 
-                       if ((last_aper_order && aper_order != last_aper_order) ||
-                           (last_aper_base && aper_base != last_aper_base) ||
-                           (last_aper_enabled && aper_enabled != last_aper_enabled)) {
-                               fix = 1;
-                               goto out;
+                       if (last_valid) {
+                               if ((aper_order != last_aper_order) ||
+                                   (aper_base != last_aper_base) ||
+                                   (aper_enabled != last_aper_enabled)) {
+                                       fix = 1;
+                                       break;
+                               }
                        }
+
                        last_aper_order = aper_order;
                        last_aper_base = aper_base;
                        last_aper_enabled = aper_enabled;
+                       last_valid = 1;
                }
        }
 
-out:
        if (!fix && !aper_enabled)
                return;