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Change the default alingment handling to not be silent failure
Index: linux-2.6.21gum/arch/arm/mm/alignment.c
===================================================================
--- linux-2.6.21gum.orig/arch/arm/mm/alignment.c
+++ linux-2.6.21gum/arch/arm/mm/alignment.c
@@ -797,6 +797,8 @@ static int __init alignment_init(void)
res->write_proc = proc_alignment_write;
#endif
+ ai_usermode = CONFIG_ALIGNMENT_HANDLING;
+
hook_fault_code(1, do_alignment, SIGILL, "alignment exception");
hook_fault_code(3, do_alignment, SIGILL, "alignment exception");
Index: linux-2.6.21gum/arch/arm/Kconfig
===================================================================
--- linux-2.6.21gum.orig/arch/arm/Kconfig
+++ linux-2.6.21gum/arch/arm/Kconfig
@@ -709,6 +709,19 @@ config ALIGNMENT_TRAP
correct operation of some network protocols. With an IP-only
configuration it is safe to say N, otherwise say Y.
+config ALIGNMENT_HANDLING
+ hex "Userspace alignment trap handling"
+ default "0x3"
+ depends on ALIGNMENT_TRAP
+ help
+ How should we handle alignment errors in userspace by default? This is a bitfield where:
+ 0 - silently ignore alignment errors (will lead to unexpected results)
+ 1 - report alignment errors through printk (will lead to unexpected results, but you'll know about them)
+ 2 - fix the alignment and make things work properly (performance degradation for un-aligned code)
+ 4 - raise SIGBUS on alignment traps
+ A good number to choose is probably either 3 (work slowly but log message) or 5 (log message and SIGBUS).
+ You can change the behavior at runtime through /proc/cpu/alignment if you have PROC_FS enabled.
+
endmenu
menu "Boot options"
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