From fe40c0af3cff3ea461cf25bddb979abc7279d4df Mon Sep 17 00:00:00 2001 From: Hiroshi Shimamoto Date: Fri, 23 Jan 2009 15:49:41 -0800 Subject: x86: uaccess: introduce try and catch framework Impact: introduce new uaccess exception handling framework Introduce {get|put}_user_try and {get|put}_user_catch as new uaccess exception handling framework. {get|put}_user_try begins exception block and {get|put}_user_catch(err) ends the block and gets err if an exception occured in {get|put}_user_ex() in the block. The exception is stored thread_info->uaccess_err. The example usage of this framework is below; int func() { int err = 0; get_user_try { get_user_ex(...); get_user_ex(...); : } get_user_catch(err); return err; } Note: get_user_ex() is not clear the value when an exception occurs, it's different from the behavior of __get_user(), but I think it doesn't matter. Signed-off-by: Hiroshi Shimamoto Signed-off-by: H. Peter Anvin --- arch/x86/mm/extable.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'arch/x86/mm') diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c index 7e8db53528a..61b41ca3b5a 100644 --- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -23,6 +23,12 @@ int fixup_exception(struct pt_regs *regs) fixup = search_exception_tables(regs->ip); if (fixup) { + /* If fixup is less than 16, it means uaccess error */ + if (fixup->fixup < 16) { + current_thread_info()->uaccess_err = -EFAULT; + regs->ip += fixup->fixup; + return 1; + } regs->ip = fixup->fixup; return 1; } -- cgit v1.2.3