On Mon, Aug 03, 2015 at 04:41:25PM +0200, Andrew Jones wrote:
> Add the hvcall for putchar and use it 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 <drjo...@redhat.com>
> ---
> lib/powerpc/io.c | 15 +++++++++++++--
> powerpc/Makefile.common | 1 +
> powerpc/cstart64.S | 27 +++++++++++++++++++++++++++
> 3 files changed, 41 insertions(+), 2 deletions(-)
>
> diff --git a/lib/powerpc/io.c b/lib/powerpc/io.c
> index cf3b6347e1e46..a7eaafeca9205 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 uart_lock;
>
> void io_init(void)
> {
> }
>
> -void puts(const char *s __unused)
> +void puts(const char *s)
> {
> + spin_lock(&uart_lock);
> + while (*s)
> + putchar(*s++);
> + spin_unlock(&uart_lock);
> }
>
> -void exit(int code __unused)
> +void exit(int code)
> {
> + halt(code);
> }
> diff --git a/powerpc/Makefile.common b/powerpc/Makefile.common
> index 5cd3ea8085038..d6356540918a5 100644
> --- a/powerpc/Makefile.common
> +++ b/powerpc/Makefile.common
> @@ -26,6 +26,7 @@ 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
> diff --git a/powerpc/cstart64.S b/powerpc/cstart64.S
> index d9b77f44f9e0e..d7c51cd352ee4 100644
> --- a/powerpc/cstart64.S
> +++ b/powerpc/cstart64.S
> @@ -6,14 +6,41 @@
> * This work is licensed under the terms of the GNU LGPL, version 2.
> */
>
> +#define HVSC .long 0x44000022
Unless your assembler is really old, you could probably use "sc 1"
inline, instead of this macro. Not that it really matters.
> +#define H_PUT_TERM_CHAR 0x58
> +
> +#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)
> + bl .main
> + bl .exit
Is this built for ppc64 or ppc64le? IIUC under the new ABI version
usually used on ppc64le, function descriptors are no longer used. And
even under the old ABI, I think the assembler now has the smarts to
avoid explicitly referencing the .-symbols.
> b halt
>
> .text
> +.align 3
>
> .globl halt
> halt:
> 1: b 1b
> +
> +.globl putchar
> +putchar:
> + sldi r6, r3, 56
> + li r3, H_PUT_TERM_CHAR
> + li r4, 0 /* vty-reg 0 means to use the default vty */
> + li r5, 1 /* sending just 1 byte */
> + HVSC
> + blr
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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