Messages in this thread | | | Date | Sun, 2 Jul 2006 15:37:18 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] i386: clean up user_mode() use |
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* pageexec@freemail.hu <pageexec@freemail.hu> wrote:
> on i386 there're two macros used for testing the userland execution > mode: user_mode() and user_mode_vm(), which is not intuitive as on > many (all?) other architectures there's only user_mode() and > architecture independent code is written with user_mode() only, and > even on i386 someone can make the wrong assumption that user_mode() > works as it does on other archs. > > two cases in point: > drivers/oprofile/cpu_buffer.c:oprofile_add_sample() uses user_mode() > which can lead to incorrect results if the interrupted task was in v86 > mode with a code segment fooling the user_mode() selector RPL check. > also, arch/i386/kernel/kprobes.c:kprobe_exceptions_notify() used to > use user_mode() whereas it really meant user_mode_vm(), this is in > fact incorrect until 2.6.17. > > to avoid such mistakes in the future, the suggested solution is to > make user_mode() on i386 consistent with the generic expectation and > make it detect any user mode execution context, that is, it should > take the role of user_mode_vm() and a new user_mode_novm() is > introduced for the i386 specific cases where v86 mode can be excluded. > in short, the patch simply does a > > user_mode_vm -> user_mode > user_mode -> user_mode_novm > > substitution as appropriate. > > Signed-off-by: PaX Team <pageexec@freemail.hu>
agreed!
Acked-by: Ingo Molnar <mingo@elte.hu>
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