rseq/selftests: Implement MIPS support

Implement support for both MIPS32 & MIPS64 in the rseq selftests, in
order to sanity check the recently enabled rseq syscall.

The tests all pass on a MIPS Boston development board running either a
MIPS32r2 interAptiv CPU & a MIPS64r6 I6500 CPU, both of which were
configured with 2 cores each of which have 2 hardware threads (VP(E)s) -
ie. 4 CPUs.

Signed-off-by: Paul Burton <[email protected]>
Reviewed-by: James Hogan <[email protected]>
Patchwork: https://patchwork.linux-mips.org/patch/19524/
Cc: Ralf Baechle <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Boqun Feng <[email protected]>
Cc: [email protected]
Cc: [email protected]

tools/testing/selftests/rseq/param_test.c

@@ -137,6 +137,30 @@ unsigned int yield_mod_cnt, nr_abort;
 	"subic. %%" INJECT_ASM_REG ", %%" INJECT_ASM_REG ", 1\n\t" \
 	"bne 222b\n\t" \
 	"333:\n\t"
+
+#elif defined(__mips__)
+
+#define RSEQ_INJECT_INPUT \
+	, [loop_cnt_1]"m"(loop_cnt[1]) \
+	, [loop_cnt_2]"m"(loop_cnt[2]) \
+	, [loop_cnt_3]"m"(loop_cnt[3]) \
+	, [loop_cnt_4]"m"(loop_cnt[4]) \
+	, [loop_cnt_5]"m"(loop_cnt[5]) \
+	, [loop_cnt_6]"m"(loop_cnt[6])
+
+#define INJECT_ASM_REG	"$5"
+
+#define RSEQ_INJECT_CLOBBER \
+	, INJECT_ASM_REG
+
+#define RSEQ_INJECT_ASM(n) \
+	"lw " INJECT_ASM_REG ", %[loop_cnt_" #n "]\n\t" \
+	"beqz " INJECT_ASM_REG ", 333f\n\t" \
+	"222:\n\t" \
+	"addiu " INJECT_ASM_REG ", -1\n\t" \
+	"bnez " INJECT_ASM_REG ", 222b\n\t" \
+	"333:\n\t"
+
 #else
 #error unsupported target
 #endif