[kvm-unit-tests PATCH v5 12/18] powerpc/ppc64: add hcall support and putchar

[Andrew Jones <drjones@redhat.com>]

Add broken sc1 detection and patching and an hcall for putchar,
to use in puts. That, along with a couple more lines in start to
prepare for C code, and a branch to main(), gets us "hello world".
Run with

qemu-system-ppc64 -M pseries            \
        -bios powerpc/boot_rom.bin      \
        -display none -serial stdio     \
        -kernel powerpc/selftest.elf

(We're still not relocating yet, that comes in a later patch. Thus,
 testing hello-world at this point requires a hacked QEMU and linking
 the unit test at QEMU's kernel load address.)

Signed-off-by: Andrew Jones <drjones@redhat.com>
Tested-by: Laurent Vivier <lvivier@redhat.com>
---
 lib/powerpc/asm/hcall.h | 37 +++++++++++++++++++++++++++++++++++++
 lib/powerpc/hcall.c     | 33 +++++++++++++++++++++++++++++++++
 lib/powerpc/io.c        | 15 +++++++++++++--
 lib/ppc64/asm/hcall.h   |  1 +
 powerpc/Makefile.common |  2 ++
 powerpc/cstart64.S      | 30 ++++++++++++++++++++++++++++++
 6 files changed, 116 insertions(+), 2 deletions(-)
 create mode 100644 lib/powerpc/asm/hcall.h
 create mode 100644 lib/powerpc/hcall.c
 create mode 100644 lib/ppc64/asm/hcall.h

diff --git a/lib/powerpc/asm/hcall.h b/lib/powerpc/asm/hcall.h
new file mode 100644
index 0000000000000..750c655562549
--- /dev/null
+++ b/lib/powerpc/asm/hcall.h
@@ -0,0 +1,37 @@
+#ifndef _ASMPOWERPC_HCALL_H_
+#define _ASMPOWERPC_HCALL_H_
+/*
+ * Copyright (C) 2016, Red Hat Inc, Andrew Jones <drjones@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.
+ */
+
+#define SC1			0x44000022
+#define SC1_REPLACEMENT		0x7c000268
+
+#define H_SUCCESS		0
+#define H_HARDWARE		-1
+#define H_FUNCTION		-2
+#define H_PRIVILEGE		-3
+#define H_PARAMETER		-4
+
+#define H_SET_DABR		0x28
+#define H_PUT_TERM_CHAR		0x58
+
+#ifndef __ASSEMBLY__
+/*
+ * hcall_have_broken_sc1 checks if we're on a host with a broken sc1.
+ * Returns 0 if we're not.
+ */
+extern int hcall_have_broken_sc1(void);
+
+/*
+ * hcall is the hypercall wrapper function. unittests may do what
+ * they like, but the framework should make all hypercalls through
+ * here to ensure they use a working sc1 instruction. @nr is the
+ * hypercall number.
+ */
+extern unsigned long hcall(unsigned long nr, ...);
+
+#endif /* !__ASSEMBLY__ */
+#endif /* _ASMPOWERPC_HCALL_H_ */
diff --git a/lib/powerpc/hcall.c b/lib/powerpc/hcall.c
new file mode 100644
index 0000000000000..cd6d26680f7cd
--- /dev/null
+++ b/lib/powerpc/hcall.c
@@ -0,0 +1,33 @@
+/*
+ * Hypercall helpers
+ *
+ * broken_sc1 probing/patching inspired by SLOF, see
+ *   SLOF:lib/libhvcall/brokensc1.c
+ *
+ * Copyright (C) 2016, Red Hat Inc, Andrew Jones <drjones@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.
+ */
+#include <asm/hcall.h>
+
+int hcall_have_broken_sc1(void)
+{
+	register unsigned long r3 asm("r3") = H_SET_DABR;
+	register unsigned long r4 asm("r4") = 0;
+
+	asm volatile("sc 1"
+	: "=r" (r3)
+	: "r" (r3), "r" (r4)
+	: "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12");
+
+	return r3 == (unsigned long)H_PRIVILEGE;
+}
+
+void putchar(int c)
+{
+	unsigned long vty = 0;		/* 0 == default */
+	unsigned long nr_chars = 1;
+	unsigned long chars = (unsigned long)c << 56;
+
+	hcall(H_PUT_TERM_CHAR, vty, nr_chars, chars);
+}
diff --git a/lib/powerpc/io.c b/lib/powerpc/io.c
index 0af45742fc900..ef90946fb1131 100644
--- a/lib/powerpc/io.c
+++ b/lib/powerpc/io.c
@@ -6,15 +6,26 @@
  * This work is licensed under the terms of the GNU LGPL, version 2.
  */
 #include <libcflat.h>
+#include <asm/spinlock.h>
+
+extern void halt(int code);
+extern void putchar(int c);
+
+static struct spinlock print_lock;
 
 void io_init(void)
 {
 }
 
-void puts(const char *s __unused)
+void puts(const char *s)
 {
+	spin_lock(&print_lock);
+	while (*s)
+		putchar(*s++);
+	spin_unlock(&print_lock);
 }
 
-void exit(int code __unused)
+void exit(int code)
 {
+	halt(code);
 }
diff --git a/lib/ppc64/asm/hcall.h b/lib/ppc64/asm/hcall.h
new file mode 100644
index 0000000000000..daabaca510cd4
--- /dev/null
+++ b/lib/ppc64/asm/hcall.h
@@ -0,0 +1 @@
+#include "../../powerpc/asm/hcall.h"
diff --git a/powerpc/Makefile.common b/powerpc/Makefile.common
index 06ec96c6e546b..b21e3933d0643 100644
--- a/powerpc/Makefile.common
+++ b/powerpc/Makefile.common
@@ -16,6 +16,7 @@ CFLAGS += -ffreestanding
 CFLAGS += -Wextra
 CFLAGS += -O2
 CFLAGS += -I lib -I lib/libfdt
+CFLAGS += -Wa,-mregnames
 
 asm-offsets = lib/$(ARCH)/asm-offsets.h
 include scripts/asm-offsets.mak
@@ -24,6 +25,7 @@ cflatobjs += lib/util.o
 cflatobjs += lib/alloc.o
 cflatobjs += lib/devicetree.o
 cflatobjs += lib/powerpc/io.o
+cflatobjs += lib/powerpc/hcall.o
 
 libgcc := $(shell $(CC) $(machine) --print-libgcc-file-name)
 
diff --git a/powerpc/cstart64.S b/powerpc/cstart64.S
index f90828dee1c19..1884d79871ba5 100644
--- a/powerpc/cstart64.S
+++ b/powerpc/cstart64.S
@@ -6,14 +6,44 @@
  * This work is licensed under the terms of the GNU LGPL, version 2.
  */
 #define __ASSEMBLY__
+#include <asm/hcall.h>
+
+#define LOAD_REG_IMMEDIATE(reg,expr)		\
+	lis	reg,(expr)@highest;		\
+	ori	reg,reg,(expr)@higher;		\
+	rldicr	reg,reg,32,31;			\
+	oris	reg,reg,(expr)@h;		\
+	ori	reg,reg,(expr)@l;
+
+#define LOAD_REG_ADDR(reg,name)			\
+	ld	reg,name@got(r2)
 
 .section .init
 
 .globl start
 start:
+	LOAD_REG_IMMEDIATE(r1, stackptr)
+	LOAD_REG_IMMEDIATE(r2, tocptr)
+
+	/* patch sc1 if needed */
+	bl	hcall_have_broken_sc1
+	cmpwi	r3, 0
+	beq	1f
+	LOAD_REG_ADDR(r3, hcall)
+	LOAD_REG_IMMEDIATE(r4, SC1_REPLACEMENT)
+	stw	r4, 0(r3)
+
+1:	bl	main
+	bl	exit
 	b	halt
 
 .text
+.align 3
+
+.globl hcall
+hcall:
+	sc	1
+	blr
 
 .globl halt
 halt:
-- 
2.4.3