[MIPS] SMTC: Interrupt mask backstop hack
To support multiple TC microthreads acting as "CPUs" within a VPE,
VPE-wide interrupt mask bits must be specially manipulated during
interrupt handling. To support legacy drivers and interrupt controller
management code, SMTC has a "backstop" to track and if necessary restore
the interrupt mask. This has some performance impact on interrupt service
overhead. Disable it only if you know what you are doing.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/entry.S b/arch/mips/kernel/entry.S
index 686249c..e29598a 100644
--- a/arch/mips/kernel/entry.S
+++ b/arch/mips/kernel/entry.S
@@ -84,6 +84,7 @@
LONG_S sp, TI_REGS($28)
jal deferred_smtc_ipi
LONG_S s0, TI_REGS($28)
+#ifdef CONFIG_MIPS_MT_SMTC_IM_BACKSTOP
/* Re-arm any temporarily masked interrupts not explicitly "acked" */
mfc0 v0, CP0_TCSTATUS
ori v1, v0, TCSTATUS_IXMT
@@ -110,6 +111,7 @@
_ehb
xor t0, t0, t3
mtc0 t0, CP0_TCCONTEXT
+#endif /* CONFIG_MIPS_MT_SMTC_IM_BACKSTOP */
#endif /* CONFIG_MIPS_MT_SMTC */
.set noat
RESTORE_TEMP