[Xen-devel] [PATCH v3 05/18] arm: poison initmem when it is freed.

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

The current byte sequence is '0xcc' which makes sense on x86,
but on ARM it is:

cccccccc        stclgt  12, cr12, [ip], {204}   ; 0xcc

Picking something more ARM applicable such as:

efefefef        svc     0x00efefef

Creates a nice crash if one executes that code:
(XEN) CPU1: Unexpected Trap: Supervisor Call

We don't have to worry about Thumb code so this instruction
is a safe to execute.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
Cc: Julien Grall <julien.grall@xxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
---
 xen/arch/arm/mm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 07e2037..0fa5623 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -995,7 +995,7 @@ void free_init_memory(void)
     paddr_t pa = virt_to_maddr(__init_begin);
     unsigned long len = __init_end - __init_begin;
     set_pte_flags_on_range(__init_begin, len, mg_rw);
-    memset(__init_begin, 0xcc, len);
+    memset(__init_begin, 0xef, len);
     set_pte_flags_on_range(__init_begin, len, mg_clear);
     init_domheap_pages(pa, pa + len);
     printk("Freed %ldkB init memory.\n", (long)(__init_end-__init_begin)>>10);
-- 
2.4.11


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