[PATCH 7/9] KVM: arm64: selftests: Add a test case for a linked breakpoint

[Reiji Watanabe]

Currently, the debug-exceptions test doesn't have a test case for
a linked breakpoint. Add a test case for the linked breakpoint to
the test.

Signed-off-by: Reiji Watanabe <reijiw at google.com>

---
 .../selftests/kvm/aarch64/debug-exceptions.c  | 59 +++++++++++++++++--
 1 file changed, 55 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/kvm/aarch64/debug-exceptions.c b/tools/testing/selftests/kvm/aarch64/debug-exceptions.c
index ab8860e3a9fa..9fccfeebccd3 100644
--- a/tools/testing/selftests/kvm/aarch64/debug-exceptions.c
+++ b/tools/testing/selftests/kvm/aarch64/debug-exceptions.c
@@ -11,6 +11,10 @@
 #define DBGBCR_EXEC	(0x0 << 3)
 #define DBGBCR_EL1	(0x1 << 1)
 #define DBGBCR_E	(0x1 << 0)
+#define DBGBCR_LBN_SHIFT	16
+#define DBGBCR_BT_SHIFT		20
+#define DBGBCR_BT_ADDR_LINK_CTX	(0x1 << DBGBCR_BT_SHIFT)
+#define DBGBCR_BT_CTX_LINK	(0x3 << DBGBCR_BT_SHIFT)
 
 #define DBGWCR_LEN8	(0xff << 5)
 #define DBGWCR_RD	(0x1 << 3)
@@ -21,7 +25,7 @@
 #define SPSR_D		(1 << 9)
 #define SPSR_SS		(1 << 21)
 
-extern unsigned char sw_bp, sw_bp2, hw_bp, hw_bp2, bp_svc, bp_brk, hw_wp, ss_start;
+extern unsigned char sw_bp, sw_bp2, hw_bp, hw_bp2, bp_svc, bp_brk, hw_wp, ss_start, hw_bp_ctx;
 static volatile uint64_t sw_bp_addr, hw_bp_addr;
 static volatile uint64_t wp_addr, wp_data_addr;
 static volatile uint64_t svc_addr;
@@ -103,6 +107,7 @@ static void reset_debug_state(void)
 	isb();
 
 	write_sysreg(0, mdscr_el1);
+	write_sysreg(0, contextidr_el1);
 
 	/* Reset all bcr/bvr/wcr/wvr registers */
 	dfr0 = read_sysreg(id_aa64dfr0_el1);
@@ -164,6 +169,28 @@ static void install_hw_bp(uint8_t bpn, uint64_t addr)
 	enable_debug_bwp_exception();
 }
 
+void install_hw_bp_ctx(uint8_t addr_bp, uint8_t ctx_bp, uint64_t addr,
+		       uint64_t ctx)
+{
+	uint32_t addr_bcr, ctx_bcr;
+
+	/* Setup a context-aware breakpoint */
+	ctx_bcr = DBGBCR_LEN8 | DBGBCR_EXEC | DBGBCR_EL1 | DBGBCR_E |
+		  DBGBCR_BT_CTX_LINK;
+	write_dbgbcr(ctx_bp, ctx_bcr);
+	write_dbgbvr(ctx_bp, ctx);
+
+	/* Setup a linked breakpoint (linked to the context-aware breakpoint) */
+	addr_bcr = DBGBCR_LEN8 | DBGBCR_EXEC | DBGBCR_EL1 | DBGBCR_E |
+		   DBGBCR_BT_ADDR_LINK_CTX |
+		   ((uint32_t)ctx_bp << DBGBCR_LBN_SHIFT);
+	write_dbgbcr(addr_bp, addr_bcr);
+	write_dbgbvr(addr_bp, addr);
+	isb();
+
+	enable_debug_bwp_exception();
+}
+
 static void install_ss(void)
 {
 	uint32_t mdscr;
@@ -177,8 +204,10 @@ static void install_ss(void)
 
 static volatile char write_data;
 
-static void guest_code(uint8_t bpn, uint8_t wpn)
+static void guest_code(uint8_t bpn, uint8_t wpn, uint8_t ctx_bpn)
 {
+	uint64_t ctx = 0x1;	/* a random context number */
+
 	GUEST_SYNC(0);
 
 	/* Software-breakpoint */
@@ -281,6 +310,19 @@ static void guest_code(uint8_t bpn, uint8_t wpn)
 		     : : : "x0");
 	GUEST_ASSERT_EQ(ss_addr[0], 0);
 
+	/* Linked hardware-breakpoint */
+	hw_bp_addr = 0;
+	reset_debug_state();
+	install_hw_bp_ctx(bpn, ctx_bpn, PC(hw_bp_ctx), ctx);
+	/* Set context id */
+	write_sysreg(ctx, contextidr_el1);
+	isb();
+	asm volatile("hw_bp_ctx: nop");
+	write_sysreg(0, contextidr_el1);
+	GUEST_ASSERT_EQ(hw_bp_addr, PC(hw_bp_ctx));
+
+	GUEST_SYNC(10);
+
 	GUEST_DONE();
 }
 
@@ -327,6 +369,7 @@ int main(int argc, char *argv[])
 	struct ucall uc;
 	int stage;
 	uint64_t aa64dfr0;
+	uint8_t brps;
 
 	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
 	ucall_init(vm, NULL);
@@ -349,8 +392,16 @@ int main(int argc, char *argv[])
 	vm_install_sync_handler(vm, VECTOR_SYNC_CURRENT,
 				ESR_EC_SVC64, guest_svc_handler);
 
-	/* Run tests with breakpoint#0 and watchpoint#0. */
-	vcpu_args_set(vcpu, 2, 0, 0);
+	/* Number of breakpoints, minus 1 */
+	brps = cpuid_get_ufield(aa64dfr0, ID_AA64DFR0_BRPS_SHIFT);
+	__TEST_REQUIRE(brps > 0, "At least two breakpoints are required");
+
+	/*
+	 * Run tests with breakpoint#0 and watchpoint#0, and the higiest
+	 * numbered (context-aware) breakpoint.
+	 */
+	vcpu_args_set(vcpu, 3, 0, 0, brps);
+
 	for (stage = 0; stage < 11; stage++) {
 		vcpu_run(vcpu);
 
-- 
2.37.1.595.g718a3a8f04-goog