[Skiboot] [PATCH v2 20/25] asm/head: add entry/exit calls

[Nicholas Piggin]

Add entry and exit C functions that can do some more complex
checks before the opal proper call. This requires saving off
volatile registers that have arguments in them.

Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
---
 asm/head.S  | 16 ++++++++++------
 core/opal.c | 27 +++++++++++++++++++++++----
 2 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/asm/head.S b/asm/head.S
index ccf094827..a786ba126 100644
--- a/asm/head.S
+++ b/asm/head.S
@@ -930,8 +930,7 @@ opal_entry:
 	std	%r1,STACK_GPR1(%r12)
 	mr	%r1,%r12
 
-	/* May save arguments for tracing */
-#ifdef OPAL_TRACE_ENTRY
+	/* Save arguments because we call C */
 	std	%r3,STACK_GPR3(%r1)
 	std	%r4,STACK_GPR4(%r1)
 	std	%r5,STACK_GPR5(%r1)
@@ -940,7 +939,7 @@ opal_entry:
 	std	%r8,STACK_GPR8(%r1)
 	std	%r9,STACK_GPR9(%r1)
 	std	%r10,STACK_GPR10(%r1)
-#endif
+
 	/* Save Token (r0), LR and r13 */
 	mflr	%r12
 	std	%r0,STACK_GPR0(%r1)
@@ -967,9 +966,12 @@ opal_entry:
 	cmpwi	%r12,0
 	bne	3f
 
-#ifdef OPAL_TRACE_ENTRY
+	/* Check entry */
 	mr	%r3,%r1
-	bl	opal_trace_entry
+	bl	opal_entry_check
+	cmpdi	%r3,0
+	bne	1f
+
 	ld	%r0,STACK_GPR0(%r1)
 	ld	%r3,STACK_GPR3(%r1)
 	ld	%r4,STACK_GPR4(%r1)
@@ -979,7 +981,6 @@ opal_entry:
 	ld	%r8,STACK_GPR8(%r1)
 	ld	%r9,STACK_GPR9(%r1)
 	ld	%r10,STACK_GPR10(%r1)
-#endif /* OPAL_TRACE_ENTRY */
 
 	/* Convert our token into a table entry and get the
 	 * function pointer. Also check the token.
@@ -997,6 +998,9 @@ opal_entry:
 	/* Jump ! */
 	bctrl
 
+	mr	%r4,%r1
+	bl	opal_exit_check
+
 1:	ld	%r12,STACK_LR(%r1)
 	mtlr	%r12
 	ld	%r13,STACK_GPR13(%r1)
diff --git a/core/opal.c b/core/opal.c
index 8095f7312..5143692d8 100644
--- a/core/opal.c
+++ b/core/opal.c
@@ -92,11 +92,9 @@ long opal_bad_token(uint64_t token)
 	return OPAL_PARAMETER;
 }
 
-/* Called from head.S, thus no prototype */
-void opal_trace_entry(struct stack_frame *eframe);
-
-void opal_trace_entry(struct stack_frame *eframe)
+static void opal_trace_entry(struct stack_frame *eframe __unused)
 {
+#ifdef OPAL_TRACE_ENTRY
 	union trace t;
 	unsigned nargs, i;
 
@@ -117,6 +115,27 @@ void opal_trace_entry(struct stack_frame *eframe)
 		t.opal.r3_to_11[i] = cpu_to_be64(eframe->gpr[3+i]);
 
 	trace_add(&t, TRACE_OPAL, offsetof(struct trace_opal, r3_to_11[nargs]));
+#endif
+}
+
+/* Called from head.S, thus no prototype */
+int64_t opal_entry_check(struct stack_frame *eframe);
+
+int64_t __attrconst opal_entry_check(struct stack_frame *eframe)
+{
+	uint64_t token = eframe->gpr[0];
+
+	opal_trace_entry(eframe);
+
+	return OPAL_SUCCESS;
+}
+
+void opal_exit_check(int64_t retval, struct stack_frame *eframe);
+
+void __attrconst opal_exit_check(int64_t retval, struct stack_frame *eframe)
+{
+	(void)retval;
+	(void)eframe;
 }
 
 void __opal_register(uint64_t token, void *func, unsigned int nargs)
-- 
2.15.0