On Wed, Feb 17, 2016 at 07:40:53PM +0100, Andrew Jones wrote:
> 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@xxxxxxxxxx>
> Tested-by: Laurent Vivier <lvivier@xxxxxxxxxx>
Reviewed-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
> ---
> 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@xxxxxxxxxx>
> + *
> + * 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@xxxxxxxxxx>
> + *
> + * 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:
--
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
Attachment:
signature.asc
Description: PGP signature
