From 972410b0232e97609fcefc8e408fe3037fcd607b Mon Sep 17 00:00:00 2001 From: Paolo 'Blaisorblade' Giarrusso Date: Fri, 31 Mar 2006 02:30:21 -0800 Subject: [PATCH] uml: clean arch_switch usage Call arch_switch also in switch_to_skas, even if it's, for now, a no-op for that case (and mark this in the comment); this will change soon. Also, arch_switch for TT mode is actually useless when the PT proxy (a complicate debugging instrumentation for TT mode) is not enabled. In fact, it only calls update_debugregs, which checks debugregs_seq against seq (to check if the registers are up-to-date - seq here means a "version number" of the registers). If the ptrace proxy is not enabled, debugregs_seq always stays 0 and update_debugregs will be a no-op. So, optimize this out (the compiler can't do it). Also, I've been disappointed by the fact that it would make a lot of sense if, after calling a successful update_debugregs(current->thread.arch.debugregs_seq), current->thread.arch.debugregs_seq were updated with the new debugregs_seq. But this is not done. Is this a bug or a feature? For all purposes, it seems a bug (otherwise the whole mechanism does not make sense, which is also a possibility to check), which causes some performance only problems (not correctness), since we write_debugregs when not needed. Also, as suggested by Jeff, remove a redundant enabling of SIGVTALRM, comprised in the subsequent local_irq_enable(). I'm just a bit dubious if ordering matters there... Signed-off-by: Paolo 'Blaisorblade' Giarrusso Acked-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/include/sysdep-i386/ptrace.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'arch/um/include/sysdep-i386') diff --git a/arch/um/include/sysdep-i386/ptrace.h b/arch/um/include/sysdep-i386/ptrace.h index c8ee9559f3a..6670cc992ec 100644 --- a/arch/um/include/sysdep-i386/ptrace.h +++ b/arch/um/include/sysdep-i386/ptrace.h @@ -14,7 +14,12 @@ #define MAX_REG_NR (UM_FRAME_SIZE / sizeof(unsigned long)) #define MAX_REG_OFFSET (UM_FRAME_SIZE) +#ifdef UML_CONFIG_PT_PROXY extern void update_debugregs(int seq); +#else +static inline void update_debugregs(int seq) {} +#endif + /* syscall emulation path in ptrace */ -- cgit v1.2.3