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ARC: [Review] Prevent incorrect syscall restarts

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Per Al Viro's "signals for dummies" https://lkml.org/lkml/2012/12/6/366
there are 3 golden rules for (not) restarting syscalls:

"	What we need to guarantee is
* restarts do not happen on signals caught in interrupts or exceptions
* restarts do not happen on signals caught in sigreturn()
* restart should happen only once, even if we get through do_signal()
  many times."

ARC Port already handled #1, this patch fixes #2 and #3.

We use the additional state in pt_regs->orig_r8 to ckh if restarting
has already been done once.

Thanks to Al Viro for spotting this.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
This commit is contained in:
Vineet Gupta
2013-01-18 15:12:19 +05:30
parent 5c39c0ab5e
commit 55bb9480f9
2 changed files with 11 additions and 4 deletions
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3
arch/arc/include/asm/ptrace.h
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@@ -100,6 +100,9 @@ struct callee_regs {
#define in_syscall(regs) (regs->event & orig_r8_IS_SCALL)
#define in_brkpt_trap(regs) (regs->event & orig_r8_IS_BRKPT)
#define syscall_wont_restart(regs) (regs->event |= orig_r8_IS_SCALL_RESTARTED)
#define syscall_restartable(regs) !(regs->event & orig_r8_IS_SCALL_RESTARTED)
#define current_pt_regs() \
({ \
/* open-coded current_thread_info() */ \