On Tue, Aug 04, 2015 at 01:50:39PM +1000, David Gibson wrote:
> 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 <drjones@xxxxxxxxxx>
> > ---
> > 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.
It makes sense to switch to sc for a new project. I'll do that.
>
> > +#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.
For now only building for ppc64, but eventually both. I'll remove the
dots.
Thanks,
drew
>
> > 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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