[PATCH v8 25/25] tests: add test with interrupted memory accesses on rv64

[Julian Ganz <neither@nut.email>]

This test aims at catching API misbehaviour w.r.t. the interaction
between interrupts and memory accesses, such as the bug fixed in

    27f347e6a1d269c533633c812321cabb249eada8
    (accel/tcg: also suppress asynchronous IRQs for cpu_io_recompile)

Because the condition for triggering misbehaviour may not be
deterministic and the cross-section between memory accesses and
interrupt handlers may be small, we have to place our trust in large
numbers. Instead of guessing/trying an arbitrary, fixed loop-bound, we
decided to loop for a fixed amount of real-time. This avoids the test
running into a time-out on slower machines while enabling a high number
of possible interactions on faster machines.

The test program sends a single '.' per 1000000 loads/stores over the
serial. This output is not captured, but may be used by developers to
gauge the number of possible interactions.

Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Signed-off-by: Julian Ganz <neither@nut.email>
---
 tests/tcg/riscv64/Makefile.softmmu-target |  6 ++
 tests/tcg/riscv64/interruptedmemory.S     | 97 +++++++++++++++++++++++
 2 files changed, 103 insertions(+)
 create mode 100644 tests/tcg/riscv64/interruptedmemory.S

diff --git a/tests/tcg/riscv64/Makefile.softmmu-target b/tests/tcg/riscv64/Makefile.softmmu-target
index d9c0036eb4..eb1ce6504a 100644
--- a/tests/tcg/riscv64/Makefile.softmmu-target
+++ b/tests/tcg/riscv64/Makefile.softmmu-target
@@ -30,5 +30,11 @@ run-plugin-doubletrap: doubletrap
 	  $(QEMU) -plugin ../plugins/libdiscons.so -d plugin -D $<.pout \
 	  $(QEMU_OPTS)$<)
 
+EXTRA_RUNS += run-plugin-interruptedmemory
+run-plugin-interruptedmemory: interruptedmemory
+	$(call run-test, $<, \
+	  $(QEMU) -plugin ../plugins/libdiscons.so -d plugin -D $<.pout \
+	  $(QEMU_OPTS)$<)
+
 # We don't currently support the multiarch system tests
 undefine MULTIARCH_TESTS
diff --git a/tests/tcg/riscv64/interruptedmemory.S b/tests/tcg/riscv64/interruptedmemory.S
new file mode 100644
index 0000000000..cd9073ee31
--- /dev/null
+++ b/tests/tcg/riscv64/interruptedmemory.S
@@ -0,0 +1,97 @@
+	.option norvc
+
+	.text
+	.global _start
+_start:
+	# Set up trap vector
+	lla	t0, trap
+	csrw	mtvec, t0
+
+	# Set up timer
+	lui	t1, 0x02004
+	sd	zero, 0(t1) # MTIMECMP0
+
+	# Enable timer interrupts
+	li	t0, 0x80
+	csrrs	zero, mie, t0
+	csrrsi	zero, mstatus, 0x8
+
+	# Set up UART
+	lui	t1, 0x10000
+	li	a0, 0x80	# DLAB=1
+	sb	a0, 3(t1)
+	li	a0, 1		# Full speed
+	sw	a0, 0(t1)
+	li	a0, 0x03	# 8N1, DLAB=0
+	sb	a0, 3(t1)
+
+	# Run test for around 60s
+	call	rtc_get
+	li	t0, 30
+	slli	t0, t0, 30 # Approx. 10e9 ns
+	add	t0, t0, a0
+0:
+	# Tight loop with memory accesses
+	li	a1, 1000000
+	la	a2, semiargs
+1:
+	ld	a0, 0(a2)
+	sd	a0, 0(a2)
+	addi	a1, a1, -1
+	bnez	a1, 1b
+
+	li	a0, '.'
+	call	send_byte
+	call	rtc_get
+	bltu	a0, t0, 0b
+
+	li	a0, '\n'
+	call	send_byte
+
+	# Exit
+	li	a0, 0
+	lla	a1, semiargs
+	li	t0, 0x20026	# ADP_Stopped_ApplicationExit
+	sd	t0, 0(a1)
+	sd	a0, 8(a1)
+	li	a0, 0x20	# TARGET_SYS_EXIT_EXTENDED
+
+	# Semihosting call sequence
+	.balign	16
+	slli	zero, zero, 0x1f
+	ebreak
+	srai	zero, zero, 0x7
+
+	j	.
+
+rtc_get:
+	# Get current time from the goldfish RTC
+	lui	t3, 0x0101
+	lw	a0, 0(t3)
+	lw	t3, 4(t3)
+	slli	t3, t3, 32
+	add	a0, a0, t3
+	ret
+
+send_byte:
+	# Send a single byte over the serial
+	lui	t3, 0x10000
+	lb	a1, 5(t3)
+	andi	a1, a1, 0x20
+	beqz	a1, send_byte
+	sb	a0, 0(t3)
+	ret
+
+	.balign 4
+trap:
+	lui	t5, 0x0200c
+	ld	t6, -0x8(t5) # MTIME
+	addi	t6, t6, 100
+	lui	t5, 0x02004
+	sd	t6, 0(t5) # MTIMECMP
+	mret
+
+	.data
+	.balign	16
+semiargs:
+	.space	16
-- 
2.49.1