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authorJiri Kosina <jkosina@suse.cz>2012-04-08 21:48:52 +0200
committerJiri Kosina <jkosina@suse.cz>2012-04-08 21:48:52 +0200
commite75d660672ddd11704b7f0fdb8ff21968587b266 (patch)
treeccb9c107744c10b553c0373e450bee3971d16c00 /arch/m68k/include/asm/switch_to.h
parent61282f37927143e45b03153f3e7b48d6b702147a (diff)
parent0034102808e0dbbf3a2394b82b1bb40b5778de9e (diff)
Merge branch 'master' into for-next
Merge with latest Linus' tree, as I have incoming patches that fix code that is newer than current HEAD of for-next. Conflicts: drivers/net/ethernet/realtek/r8169.c
Diffstat (limited to 'arch/m68k/include/asm/switch_to.h')
-rw-r--r--arch/m68k/include/asm/switch_to.h41
1 files changed, 41 insertions, 0 deletions
diff --git a/arch/m68k/include/asm/switch_to.h b/arch/m68k/include/asm/switch_to.h
new file mode 100644
index 00000000000..16fd6b63498
--- /dev/null
+++ b/arch/m68k/include/asm/switch_to.h
@@ -0,0 +1,41 @@
+#ifndef _M68K_SWITCH_TO_H
+#define _M68K_SWITCH_TO_H
+
+/*
+ * switch_to(n) should switch tasks to task ptr, first checking that
+ * ptr isn't the current task, in which case it does nothing. This
+ * also clears the TS-flag if the task we switched to has used the
+ * math co-processor latest.
+ */
+/*
+ * switch_to() saves the extra registers, that are not saved
+ * automatically by SAVE_SWITCH_STACK in resume(), ie. d0-d5 and
+ * a0-a1. Some of these are used by schedule() and its predecessors
+ * and so we might get see unexpected behaviors when a task returns
+ * with unexpected register values.
+ *
+ * syscall stores these registers itself and none of them are used
+ * by syscall after the function in the syscall has been called.
+ *
+ * Beware that resume now expects *next to be in d1 and the offset of
+ * tss to be in a1. This saves a few instructions as we no longer have
+ * to push them onto the stack and read them back right after.
+ *
+ * 02/17/96 - Jes Sorensen (jds@kom.auc.dk)
+ *
+ * Changed 96/09/19 by Andreas Schwab
+ * pass prev in a0, next in a1
+ */
+asmlinkage void resume(void);
+#define switch_to(prev,next,last) do { \
+ register void *_prev __asm__ ("a0") = (prev); \
+ register void *_next __asm__ ("a1") = (next); \
+ register void *_last __asm__ ("d1"); \
+ __asm__ __volatile__("jbsr resume" \
+ : "=a" (_prev), "=a" (_next), "=d" (_last) \
+ : "0" (_prev), "1" (_next) \
+ : "d0", "d2", "d3", "d4", "d5"); \
+ (last) = _last; \
+} while (0)
+
+#endif /* _M68K_SWITCH_TO_H */