kselftest/arm64: Count SIGUSR2 deliveries in FP stress tests

Currently the floating point stress tests mostly support testing that the
data they are checking can be disrupted from a signal handler triggered by
SIGUSR1. This is not properly implemented for all the tests and in testing
is frequently modified to just handle the signal without corrupting data in
order to ensure that signal handling does not corrupt data. Directly support
this usage by installing a SIGUSR2 handler which simply counts the signal
delivery.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220829154452.824870-3-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

tools/testing/selftests/arm64/fp/asm-offsets.h

@@ -3,6 +3,7 @@
 #define sa_handler 0
 #define sa_mask_sz 8
 #define SIGUSR1 10
+#define SIGUSR2 12
 #define SIGTERM 15
 #define SIGINT 2
 #define SIGABRT 6

tools/testing/selftests/arm64/fp/fpsimd-test.S

@@ -151,6 +151,15 @@ function irritator_handler
 	ret
 endfunction
 
+function tickle_handler
+	// Increment the signal count (x23):
+	ldr	x0, [x2, #ucontext_regs + 8 * 23]
+	add	x0, x0, #1
+	str	x0, [x2, #ucontext_regs + 8 * 23]
+
+	ret
+endfunction
+
 function terminate_handler
 	mov	w21, w0
 	mov	x20, x2
@@ -255,6 +264,12 @@ _start:
 	orr	w2, w2, #SA_NODEFER
 	bl	setsignal
 
+	mov	w0, #SIGUSR2
+	adr	x1, tickle_handler
+	mov	w2, #SA_SIGINFO
+	orr	w2, w2, #SA_NODEFER
+	bl	setsignal
+
 	mov	x22, #0		// generation number, increments per iteration
 .Ltest_loop:
 

tools/testing/selftests/arm64/fp/sve-test.S

@@ -314,6 +314,15 @@ function irritator_handler
 	ret
 endfunction
 
+function tickle_handler
+	// Increment the signal count (x23):
+	ldr	x0, [x2, #ucontext_regs + 8 * 23]
+	add	x0, x0, #1
+	str	x0, [x2, #ucontext_regs + 8 * 23]
+
+	ret
+endfunction
+
 function terminate_handler
 	mov	w21, w0
 	mov	x20, x2
@@ -423,6 +432,12 @@ _start:
 	orr	w2, w2, #SA_NODEFER
 	bl	setsignal
 
+	mov	w0, #SIGUSR2
+	adr	x1, tickle_handler
+	mov	w2, #SA_SIGINFO
+	orr	w2, w2, #SA_NODEFER
+	bl	setsignal
+
 #ifdef SSVE
 	smstart_sm		// syscalls will have exited streaming mode
 #endif

tools/testing/selftests/arm64/fp/za-test.S

@@ -167,6 +167,15 @@ function irritator_handler
 	ret
 endfunction
 
+function tickle_handler
+	// Increment the signal count (x23):
+	ldr	x0, [x2, #ucontext_regs + 8 * 23]
+	add	x0, x0, #1
+	str	x0, [x2, #ucontext_regs + 8 * 23]
+
+	ret
+endfunction
+
 function terminate_handler
 	mov	w21, w0
 	mov	x20, x2
@@ -273,6 +282,12 @@ _start:
 	orr	w2, w2, #SA_NODEFER
 	bl	setsignal
 
+	mov	w0, #SIGUSR2
+	adr	x1, tickle_handler
+	mov	w2, #SA_SIGINFO
+	orr	w2, w2, #SA_NODEFER
+	bl	setsignal
+
 	mov	x22, #0		// generation number, increments per iteration
 .Ltest_loop:
 	rdsvl	0, 8