Messages in this thread | | | Date | Mon, 22 Dec 2008 21:47:52 -0800 | From | Hiroshi Shimamoto <> | Subject | Re: [RFC -tip 2/4] x86: uaccess: introduce __{get|put}_user exception handling framework |
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Brian Gerst wrote: > On Tue, Dec 23, 2008 at 12:22 AM, Hiroshi Shimamoto > <h-shimamoto@ct.jp.nec.com> wrote: >> From: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> >> >> Impact: introduce new framework >> >> Introduce exception handling framework. >> __{get|put}_user_ex_try() begins exception block and >> __{get|put}_user_ex_catch() ends block and if an exception occurred in this >> block using __{get|put}_user_ex, direct jump to __{get|put}_user_ex_catch() >> and err is set to specified value. > > You shouldn't do this. According to the gcc manual[1], "Speaking of > labels, jumps from one asm to another are not supported. The > compiler's optimizers do not know about these jumps, and therefore > they cannot take account of them when deciding how to optimize." > > [1] http://gcc.gnu.org/onlinedocs/gcc-4.3.2/gcc/Extended-Asm.html > thanks so much for this information! I didn't know about this and it's what I want to know, thinking about this series.
Thanks, Hiroshi
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