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x86-64: Set siginfo and context on vsyscall emulation faults

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To make this work, we teach the page fault handler how to send
signals on failed uaccess.  This only works for user addresses
(kernel addresses will never hit the page fault handler in the
first place), so we need to generate signals for those
separately.

This gets the tricky case right: if the user buffer spans
multiple pages and only the second page is invalid, we set
cr2 and si_addr correctly.  UML relies on this behavior to
"fault in" pages as needed.

We steal a bit from thread_info.uaccess_err to enable this.
Before this change, uaccess_err was a 32-bit boolean value.

This fixes issues with UML when vsyscall=emulate.

Reported-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: richard -rw- weinberger <richard.weinberger@gmail.com>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/4c8f91de7ec5cd2ef0f59521a04e1015f11e42b4.1320712291.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Andy Lutomirski
2011-11-07 16:33:40 -08:00
committed by Ingo Molnar
parent 01acc26908
commit 4fc3490114
5 changed files with 87 additions and 17 deletions
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3
arch/x86/include/asm/thread_info.h
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@@ -40,7 +40,8 @@ struct thread_info {
*/
__u8 supervisor_stack[0];
#endif
int uaccess_err;
int sig_on_uaccess_error:1;
int uaccess_err:1; /* uaccess failed */
};
#define INIT_THREAD_INFO(tsk) \