[MIPS] MT: Improved multithreading support.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/head.S b/arch/mips/kernel/head.S
index 2e9122a..bdf6f6e 100644
--- a/arch/mips/kernel/head.S
+++ b/arch/mips/kernel/head.S
@@ -18,6 +18,7 @@
#include <linux/threads.h>
#include <asm/asm.h>
+#include <asm/asmmacro.h>
#include <asm/regdef.h>
#include <asm/page.h>
#include <asm/mipsregs.h>
@@ -82,12 +83,33 @@
*/
.macro setup_c0_status set clr
.set push
+#ifdef CONFIG_MIPS_MT_SMTC
+ /*
+ * For SMTC, we need to set privilege and disable interrupts only for
+ * the current TC, using the TCStatus register.
+ */
+ mfc0 t0, CP0_TCSTATUS
+ /* Fortunately CU 0 is in the same place in both registers */
+ /* Set TCU0, TMX, TKSU (for later inversion) and IXMT */
+ li t1, ST0_CU0 | 0x08001c00
+ or t0, t1
+ /* Clear TKSU, leave IXMT */
+ xori t0, 0x00001800
+ mtc0 t0, CP0_TCSTATUS
+ ehb
+ /* We need to leave the global IE bit set, but clear EXL...*/
+ mfc0 t0, CP0_STATUS
+ or t0, ST0_CU0 | ST0_EXL | ST0_ERL | \set | \clr
+ xor t0, ST0_EXL | ST0_ERL | \clr
+ mtc0 t0, CP0_STATUS
+#else
mfc0 t0, CP0_STATUS
or t0, ST0_CU0|\set|0x1f|\clr
xor t0, 0x1f|\clr
mtc0 t0, CP0_STATUS
.set noreorder
sll zero,3 # ehb
+#endif
.set pop
.endm
@@ -134,6 +156,24 @@
ARC64_TWIDDLE_PC
+#ifdef CONFIG_MIPS_MT_SMTC
+ /*
+ * In SMTC kernel, "CLI" is thread-specific, in TCStatus.
+ * We still need to enable interrupts globally in Status,
+ * and clear EXL/ERL.
+ *
+ * TCContext is used to track interrupt levels under
+ * service in SMTC kernel. Clear for boot TC before
+ * allowing any interrupts.
+ */
+ mtc0 zero, CP0_TCCONTEXT
+
+ mfc0 t0, CP0_STATUS
+ ori t0, t0, 0xff1f
+ xori t0, t0, 0x001e
+ mtc0 t0, CP0_STATUS
+#endif /* CONFIG_MIPS_MT_SMTC */
+
PTR_LA t0, __bss_start # clear .bss
LONG_S zero, (t0)
PTR_LA t1, __bss_stop - LONGSIZE
@@ -166,8 +206,25 @@
* function after setting up the stack and gp registers.
*/
NESTED(smp_bootstrap, 16, sp)
+#ifdef CONFIG_MIPS_MT_SMTC
+ /*
+ * Read-modify-writes of Status must be atomic, and this
+ * is one case where CLI is invoked without EXL being
+ * necessarily set. The CLI and setup_c0_status will
+ * in fact be redundant for all but the first TC of
+ * each VPE being booted.
+ */
+ DMT 10 # dmt t2 /* t0, t1 are used by CLI and setup_c0_status() */
+ jal mips_ihb
+#endif /* CONFIG_MIPS_MT_SMTC */
setup_c0_status_sec
smp_slave_setup
+#ifdef CONFIG_MIPS_MT_SMTC
+ andi t2, t2, VPECONTROL_TE
+ beqz t2, 2f
+ EMT # emt
+2:
+#endif /* CONFIG_MIPS_MT_SMTC */
j start_secondary
END(smp_bootstrap)
#endif /* CONFIG_SMP */