For fadump case, passing additional parameters to dump capture kernel
helps in minimizing the memory footprint for it and also provides the
flexibility to disable components/modules, like hugepages, that are
hindering the boot process of the special dump capture environment.
Set up a dedicated parameter area to be passed to the capture kernel.
This area type is defined as RTAS_FADUMP_PARAM_AREA. Sysfs attribute
'/sys/kernel/fadump/bootargs_append' is exported to the userspace to
specify the additional parameters to be passed to the capture kernel
Signed-off-by: Hari Bathini <hbath...@linux.ibm.com>
---
arch/powerpc/include/asm/fadump-internal.h | 3 +
arch/powerpc/kernel/fadump.c | 80 ++++++++++++++++++++
arch/powerpc/platforms/powernv/opal-fadump.c | 6 +-
arch/powerpc/platforms/pseries/rtas-fadump.c | 35 ++++++++-
arch/powerpc/platforms/pseries/rtas-fadump.h | 11 ++-
5 files changed, 126 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/include/asm/fadump-internal.h
b/arch/powerpc/include/asm/fadump-internal.h
index b3956c400519..81629226b15f 100644
--- a/arch/powerpc/include/asm/fadump-internal.h
+++ b/arch/powerpc/include/asm/fadump-internal.h
@@ -97,6 +97,8 @@ struct fw_dump {
unsigned long cpu_notes_buf_vaddr;
unsigned long cpu_notes_buf_size;
+ unsigned long param_area;
+
/*
* Maximum size supported by firmware to copy from source to
* destination address per entry.
@@ -111,6 +113,7 @@ struct fw_dump {
unsigned long dump_active:1;
unsigned long dump_registered:1;
unsigned long nocma:1;
+ unsigned long param_area_supported:1;
struct fadump_ops *ops;
};
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 757681658dda..98f089747ac9 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -1470,6 +1470,7 @@ static ssize_t mem_reserved_show(struct kobject
*kobj,
return sprintf(buf, "%ld\n", fw_dump.reserve_dump_area_size);
}
+
static ssize_t registered_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
@@ -1477,6 +1478,43 @@ static ssize_t registered_show(struct kobject
*kobj,
return sprintf(buf, "%d\n", fw_dump.dump_registered);
}
+static ssize_t bootargs_append_show(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ char *buf)
+{
+ return sprintf(buf, "%s\n", (char *)__va(fw_dump.param_area));
+}
+
+static ssize_t bootargs_append_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ char *params;
+
+ if (!fw_dump.fadump_enabled || fw_dump.dump_active)
+ return -EPERM;
+
+ if (count >= COMMAND_LINE_SIZE)
+ return -EINVAL;
+
+ /*
+ * Fail here instead of handling this scenario with
+ * some silly workaround in capture kernel.
+ */
+ if (saved_command_line_len + count >= COMMAND_LINE_SIZE) {
+ pr_err("Appending parameters exceeds cmdline size!\n");
+ return -ENOSPC;
+ }
+
+ params = __va(fw_dump.param_area);
+ strscpy_pad(params, buf, COMMAND_LINE_SIZE);
+ /* Remove newline character at the end. */
+ if (params[count-1] == '\n')
+ params[count-1] = '\0';
+
+ return count;
+}
+
static ssize_t registered_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
@@ -1535,6 +1573,7 @@ static struct kobj_attribute release_attr =
__ATTR_WO(release_mem);
static struct kobj_attribute enable_attr = __ATTR_RO(enabled);
static struct kobj_attribute register_attr = __ATTR_RW(registered);
static struct kobj_attribute mem_reserved_attr =
__ATTR_RO(mem_reserved);
+static struct kobj_attribute bootargs_append_attr =
__ATTR_RW(bootargs_append);
static struct attribute *fadump_attrs[] = {
&enable_attr.attr,
@@ -1611,6 +1650,46 @@ static void __init fadump_init_files(void)
return;
}
+/*
+ * Reserve memory to store additional parameters to be passed
+ * for fadump/capture kernel.
+ */
+static void fadump_setup_param_area(void)
+{
+ phys_addr_t range_start, range_end;
+
+ if (!fw_dump.param_area_supported || fw_dump.dump_active)
+ return;
+
+ /* This memory can't be used by PFW or bootloader as it is shared
across kernels */
+ if (radix_enabled()) {
+ /*
+ * Anywhere in the upper half should be good enough as all
memory
+ * is accessible in real mode.
+ */
+ range_start = memblock_end_of_DRAM() / 2;
+ range_end = memblock_end_of_DRAM();
+ } else {
+ /*
+ * Passing additional parameters is supported for hash MMU only
+ * if the first memory block size is 768MB or higher.
+ */
+ if (ppc64_rma_size < 0x30000000)
+ return;
+
+ /* 640 MB to 768 MB is not used by bootloader */
+ range_start = 0x28000000;
+ range_end = range_start + 0x4000000;
+ }
+
+ fw_dump.param_area = memblock_phys_alloc_range(COMMAND_LINE_SIZE,
+ COMMAND_LINE_SIZE,
+ range_start,
+ range_end);
