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

[Laurent Dufour <ldufour@linux.vnet.ibm.com>]

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>
---
 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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