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f8fa5448fc
This patch reorganizes break_fault() to optimistically assume that a system-call is being performed from user-space (which is almost always the case). If it turns out that (a) we're not being called due to a system call or (b) we're being called from within the kernel, we fixup the no-longer-valid assumptions in non_syscall() and .break_fixup(), respectively. With this approach, there are 3 major phases: - Phase 1: Read various control & application registers, in particular the current task pointer from AR.K6. - Phase 2: Do all memory loads (load system-call entry, load current_thread_info()->flags, prefetch kernel register-backing store) and switch to kernel register-stack. - Phase 3: Call ia64_syscall_setup() and invoke syscall-handler. Good for 26-30 cycles of improvement on break-based syscall-path. Signed-off-by: David Mosberger-Tang <davidm@hpl.hp.com> Signed-off-by: Tony Luck <tony.luck@intel.com> |
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