lkml.org 
[lkml]   [2011]   [Nov]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
SubjectOverlapping reserved regions at boot
Date
Hello,

while working on the upcoming SLES11 SP2, I ran into an issue with booting the
panic kernel on a kernel crash. In the first iteration I found out that the
initial register backing store gets overwritten with zeroes, causing a kernel
crash shortly afterwards.

Further investigation revealed that rsvd_region[] contains overlapping
entries: find_memmap_space() returns a pointer which lies between KERNEL_START
and _end. This is correct with the EFI memmap as patched by the kexec
purgatory code. That code removes vmlinux LOAD segments from the usable map,
but there is a pretty large hole between the gate section and the per-cpu
section.

With the following patch, the panic kernel can boot and save the crash dump.

Signed-off-by: Petr Tesarik <ptesarik@suse.cz>

--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -225,6 +225,23 @@
}
}

+/* merge overlaps */
+static int __init
+merge_regions (struct rsvd_region *rsvd_region, int max)
+{
+ int i;
+ for (i = 1; i < max; ++i) {
+ if (rsvd_region[i].start >= rsvd_region[i-1].end)
+ continue;
+ if (rsvd_region[i].end > rsvd_region[i-1].end)
+ rsvd_region[i-1].end = rsvd_region[i].end;
+ --max;
+ memmove(&rsvd_region[i], &rsvd_region[i+1],
+ (max - i) * sizeof(struct rsvd_region));
+ }
+ return max;
+}
+
/*
* Request address space for all standard resources
*/
@@ -275,6 +292,7 @@
if (ret == 0 && size > 0) {
if (!base) {
sort_regions(rsvd_region, *n);
+ *n = merge_regions(rsvd_region, *n);
base = kdump_find_rsvd_region(size,
rsvd_region, *n);
}
@@ -392,6 +410,7 @@
BUG_ON(IA64_MAX_RSVD_REGIONS + 1 < n);

sort_regions(rsvd_region, num_rsvd_regions);
+ num_rsvd_regions = merge_regions(rsvd_region, num_rsvd_regions);
}



\
 
 \ /
  Last update: 2011-11-29 15:05    [W:0.054 / U:0.780 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site