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authorPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>2006-03-31 02:30:21 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-31 12:18:52 -0800
commit972410b0232e97609fcefc8e408fe3037fcd607b (patch)
tree2de18ed5d823dc7e24c0171f720f6354a9cd57e4 /arch/um/sys-i386/ptrace.c
parentfbdf2161552a2065047e5df2dbf9ebf69d66a0e9 (diff)
[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 <blaisorblade@yahoo.it> Acked-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/um/sys-i386/ptrace.c')
-rw-r--r--arch/um/sys-i386/ptrace.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/arch/um/sys-i386/ptrace.c b/arch/um/sys-i386/ptrace.c
index ff94eded93eb..927fcd955651 100644
--- a/arch/um/sys-i386/ptrace.c
+++ b/arch/um/sys-i386/ptrace.c
@@ -15,9 +15,13 @@
#include "sysdep/sigcontext.h"
#include "sysdep/sc.h"
-void arch_switch(void)
+void arch_switch_to_tt(struct task_struct *from, struct task_struct *to)
+{
+ update_debugregs(to->thread.arch.debugregs_seq);
+}
+
+void arch_switch_to_skas(struct task_struct *from, struct task_struct *to)
{
- update_debugregs(current->thread.arch.debugregs_seq);
}
int is_syscall(unsigned long addr)