Re: [PATCH] kexec/ppc64 Enable early kernel's OPAL calls

[Mahesh Jagannath Salgaonkar <mahesh@linux.vnet.ibm.com>]

On 01/24/2014 07:46 PM, Laurent Dufour wrote:
> When the kernel is built with CONFIG_PPC_EARLY_DEBUG_OPAL set, it is
> expecting to get r8 and r9 filled respectively with OPAL base address and
> OPAL entry address (arc/power/head_64.S).
> 
> On the new powernv platform, having these 2 registers set allows the kernel
> to perform OPAL calls before it parse the device tree.
> 
> Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>

Tested-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>

> ---
>  kexec/arch/ppc64/kexec-elf-ppc64.c     |   43 ++++++++++++++++++++++++++++++++
>  purgatory/arch/ppc64/purgatory-ppc64.c |    2 +
>  purgatory/arch/ppc64/v2wrap.S          |    4 +++
>  3 files changed, 49 insertions(+)
> 
> diff --git a/kexec/arch/ppc64/kexec-elf-ppc64.c b/kexec/arch/ppc64/kexec-elf-ppc64.c
> index 7d49d8a..ce10367 100644
> --- a/kexec/arch/ppc64/kexec-elf-ppc64.c
> +++ b/kexec/arch/ppc64/kexec-elf-ppc64.c
> @@ -71,6 +71,26 @@ void arch_reuse_initrd(void)
>  	reuse_initrd = 1;
>  }
> 
> +static int read_prop(char *name, void *value, size_t len)
> +{
> +	int fd;
> +	size_t rlen;
> +
> +	fd = open(name, O_RDONLY);
> +	if (fd == -1)
> +		return -1;
> +
> +	rlen = read(fd, value, len);
> +	if (rlen < 0)
> +		fprintf(stderr, "Warning : Can't read %s : %s",
> +			name, strerror(errno));
> +	else if (rlen != len)
> +		fprintf(stderr, "Warning : short read from %s", name);
> +
> +	close(fd);
> +	return 0;
> +}
> +
>  int elf_ppc64_load(int argc, char **argv, const char *buf, off_t len,
>  			struct kexec_info *info)
>  {
> @@ -90,6 +110,7 @@ int elf_ppc64_load(int argc, char **argv, const char *buf, off_t len,
>  	int i;
>  	int result, opt;
>  	uint64_t my_kernel, my_dt_offset;
> +	uint64_t my_opal_base = 0, my_opal_entry = 0;
>  	unsigned int my_panic_kernel;
>  	uint64_t my_stack, my_backup_start;
>  	uint64_t toc_addr;
> @@ -246,6 +267,20 @@ int elf_ppc64_load(int argc, char **argv, const char *buf, off_t len,
>  	*rsvmap_ptr = cpu_to_be64((uint64_t)be32_to_cpu(bb_ptr->totalsize));
>  #endif
> 
> +	if (read_prop("/proc/device-tree/ibm,opal/opal-base-address",
> +		      &my_opal_base, sizeof(my_opal_base)) == 0) {
> +		my_opal_base = be64_to_cpu(my_opal_base);
> +		elf_rel_set_symbol(&info->rhdr, "opal_base",
> +				   &my_opal_base, sizeof(my_opal_base));
> +	}
> +
> +	if (read_prop("/proc/device-tree/ibm,opal/opal-entry-address",
> +		      &my_opal_entry, sizeof(my_opal_entry)) == 0) {
> +		my_opal_entry = be64_to_cpu(my_opal_entry);
> +		elf_rel_set_symbol(&info->rhdr, "opal_entry",
> +				   &my_opal_entry, sizeof(my_opal_entry));
> +	}
> +
>  	/* Set kernel */
>  	elf_rel_set_symbol(&info->rhdr, "kernel", &my_kernel, sizeof(my_kernel));
> 
> @@ -306,7 +341,13 @@ int elf_ppc64_load(int argc, char **argv, const char *buf, off_t len,
>  	toc_addr = 0;
>  	my_run_at_load = 0;
>  	my_debug = 0;
> +	my_opal_base = 0;
> +	my_opal_entry = 0;
> 
> +	elf_rel_get_symbol(&info->rhdr, "opal_base", &my_opal_base,
> +			   sizeof(my_opal_base));
> +	elf_rel_get_symbol(&info->rhdr, "opal_entry", &my_opal_entry,
> +			   sizeof(my_opal_entry));
>  	elf_rel_get_symbol(&info->rhdr, "kernel", &my_kernel, sizeof(my_kernel));
>  	elf_rel_get_symbol(&info->rhdr, "dt_offset", &my_dt_offset,
>  				sizeof(my_dt_offset));
> @@ -333,6 +374,8 @@ int elf_ppc64_load(int argc, char **argv, const char *buf, off_t len,
>  	dbgprintf("toc_addr is %llx\n", (unsigned long long)toc_addr);
>  	dbgprintf("purgatory size is %zu\n", purgatory_size);
>  	dbgprintf("debug is %d\n", my_debug);
> +	dbgprintf("opal_base is %llx\n", (unsigned long long) my_opal_base);
> +	dbgprintf("opal_entry is %llx\n", (unsigned long long) my_opal_entry);
> 
>  	for (i = 0; i < info->nr_segments; i++)
>  		fprintf(stderr, "segment[%d].mem:%p memsz:%zu\n", i,
> diff --git a/purgatory/arch/ppc64/purgatory-ppc64.c b/purgatory/arch/ppc64/purgatory-ppc64.c
> index 0b6d326..7248ac8 100644
> --- a/purgatory/arch/ppc64/purgatory-ppc64.c
> +++ b/purgatory/arch/ppc64/purgatory-ppc64.c
> @@ -29,6 +29,8 @@ unsigned long dt_offset = 0;
>  unsigned long my_toc = 0;
>  unsigned long kernel = 0;
>  unsigned int debug = 0;
> +unsigned long opal_base = 0;
> +unsigned long opal_entry = 0;
> 
>  void setup_arch(void)
>  {
> diff --git a/purgatory/arch/ppc64/v2wrap.S b/purgatory/arch/ppc64/v2wrap.S
> index 2761c14..6fc62e3 100644
> --- a/purgatory/arch/ppc64/v2wrap.S
> +++ b/purgatory/arch/ppc64/v2wrap.S
> @@ -95,6 +95,10 @@ master:
>  	blt     80f
>  	stw     17,28(3)        # save my cpu number as boot_cpu_phys
>  80:
> +	LOADADDR(6,opal_base)	# For OPAL early debug
> +	ld      8,0(6)          # load the OPAL base address in r8
> +	LOADADDR(6,opal_entry)	# For OPAL early debug
> +	ld      9,0(6)          # load the OPAL entry address in r9
>  	LOADADDR(6,kernel)
>  	ld      4,0(6)          # load the kernel address
>  	LOADADDR(6,run_at_load) # the load flag
> 


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