[RESEND PATCH v5 07/11] ppc64/kexec_file: enable early kernel's OPAL calls

Hari Bathini
2020-07-26T19:39:24Z

Kernel built with CONFIG_PPC_EARLY_DEBUG_OPAL enabled expects r8 & r9
to be filled with OPAL base & entry addresses respectively. Setting
these registers allows the kernel to perform OPAL calls before the
device tree is parsed.

Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
---

v4 -> v5:
* New patch. Updated opal_base & opal_entry values in r8 & r9 respectively.
This change was part of the below dropped patch in v4:
- https://lore.kernel.org/patchwork/patch/1275667/

arch/powerpc/kexec/file_load_64.c | 16 ++++++++++++++++
arch/powerpc/purgatory/trampoline_64.S | 15 +++++++++++++++
2 files changed, 31 insertions(+)

diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
index 8df085a22fd7..a5c1442590b2 100644
--- a/arch/powerpc/kexec/file_load_64.c
+++ b/arch/powerpc/kexec/file_load_64.c
@@ -713,6 +713,8 @@ int setup_purgatory_ppc64(struct kimage *image, const void *slave_code,
const void *fdt, unsigned long kernel_load_addr,
unsigned long fdt_load_addr)
{
+ struct device_node *dn = NULL;
+ uint64_t val;
int ret;

ret = setup_purgatory(image, slave_code, fdt, kernel_load_addr,
@@ -735,9 +737,23 @@ int setup_purgatory_ppc64(struct kimage *image, const void *slave_code,
goto out;
}

+ /* Setup OPAL base & entry values */
+ dn = of_find_node_by_path("/ibm,opal");
+ if (dn) {
+ of_property_read_u64(dn, "opal-base-address", &val);
+ ret = kexec_purgatory_get_set_symbol(image, "opal_base", &val,
+ sizeof(val), false);
+ if (ret)
+ goto out;
+
+ of_property_read_u64(dn, "opal-entry-address", &val);
+ ret = kexec_purgatory_get_set_symbol(image, "opal_entry", &val,
+ sizeof(val), false);
+ }
out:
if (ret)
pr_err("Failed to setup purgatory symbols");
+ of_node_put(dn);
return ret;
}

diff --git a/arch/powerpc/purgatory/trampoline_64.S b/arch/powerpc/purgatory/trampoline_64.S
index a5a83c3f53e6..464af8e8a4cb 100644
--- a/arch/powerpc/purgatory/trampoline_64.S
+++ b/arch/powerpc/purgatory/trampoline_64.S
@@ -61,6 +61,10 @@ master:
li %r4,28
STWX_BE %r17,%r3,%r4 /* Store my cpu as __be32 at byte 28 */
1:
+ /* Load opal base and entry values in r8 & r9 respectively */
+ ld %r8,(opal_base - 0b)(%r18)
+ ld %r9,(opal_entry - 0b)(%r18)
+
/* load the kernel address */
ld %r4,(kernel - 0b)(%r18)

@@ -102,6 +106,17 @@ dt_offset:
.8byte 0x0
.size dt_offset, . - dt_offset

+ .balign 8
+ .globl opal_base
+opal_base:
+ .8byte 0x0
+ .size opal_base, . - opal_base
+
+ .balign 8
+ .globl opal_entry
+opal_entry:
+ .8byte 0x0
+ .size opal_entry, . - opal_entry

.data
.balign 8