[Lguest] [PATCH] Fix lguest bzImage loading with CONFIG_RELOCATABLE=y
Rusty Russell
rusty at rustcorp.com.au
Fri Jul 27 13:35:43 EST 2007
Jason Yeh sent his crashing .config: bzImages made with
CONFIG_RELOCATABLE=y put the relocs where the BSS is expected, and we
crash with unusual results such as:
lguest: unhandled trap 14 at 0xc0122ae1 (0xa9)
Relying on BSS being zero was merely laziness on my part.
Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
diff -r cf2bfb364110 drivers/lguest/lguest.c
--- a/drivers/lguest/lguest.c Fri Jul 27 13:04:22 2007 +1000
+++ b/drivers/lguest/lguest.c Fri Jul 27 13:15:22 2007 +1000
@@ -1039,6 +1039,11 @@ __init void lguest_init(void *boot)
* the normal data segment to get through booting. */
asm volatile ("mov %0, %%fs" : : "r" (__KERNEL_DS) : "memory");
+ /* Clear the part of the kernel data which is expected to be zero.
+ * Normally it will be anyway, but if we're loading from a bzImage with
+ * CONFIG_RELOCATALE=y, the relocations will be sitting here. */
+ memset(__bss_start, 0, __bss_stop - __bss_start);
+
/* The Host uses the top of the Guest's virtual address space for the
* Host<->Guest Switcher, and it tells us how much it needs in
* lguest_data.reserve_mem, set up on the LGUEST_INIT hypercall. */
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