[powerpc] Export memory_limit via device tree

The following series exports the linux memory_limit set by
the mem= parameter via device-tree, so that kexec-tools
can limit the crash regions to the actual memory used by
the kernel.

Change since V1:

 * Added a patch to change the type of memory_limit to a
   fixed size(unsigned long long) from 'phys_addr_t' (which
   is 32bit on some ppc32 and 64 bit on ppc64 and some ppc32)

 * Rebased the patch to use recently fixed prom_update_property()
   which would add the property if it didn't exist.

---

Suzuki K. Poulose (2):
      [powerpc] Change memory_limit from phys_addr_t to unsigned long long
      [powerpc] Export memory limit via device tree


 arch/powerpc/include/asm/setup.h    |    2 +-
 arch/powerpc/kernel/fadump.c        |    3 +--
 arch/powerpc/kernel/machine_kexec.c |   14 +++++++++++++-
 arch/powerpc/kernel/prom.c          |    2 +-
 arch/powerpc/mm/mem.c               |    2 +-
 5 files changed, 17 insertions(+), 6 deletions(-)

-- 
Suzuki

There are some device-tree nodes, whose values are of type phys_addr_t.
The phys_addr_t is variable sized based on the CONFIG_PHSY_T_64BIT.

Change these to a fixed unsigned long long for consistency.

This patch does the change only for memory_limit.

The following is a list of such variables which need the change:

 1) kernel_end, crashk_size - in arch/powerpc/kernel/machine_kexec.c

 2) (struct resource *)crashk_res.start - We could export a local static
    variable from machine_kexec.c.

Changing the above values might break the kexec-tools. So, I will
fix kexec-tools first to handle the different sized values and then change
 the above.

Suggested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Suzuki K. Poulose <redacted>
---

 arch/powerpc/include/asm/setup.h    |    2 +-
 arch/powerpc/kernel/fadump.c        |    3 +--
 arch/powerpc/kernel/machine_kexec.c |    2 +-
 arch/powerpc/kernel/prom.c          |    2 +-
 arch/powerpc/mm/mem.c               |    2 +-
 5 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/include/asm/setup.h b/arch/powerpc/include/asm/setup.h
index d084ce1..8b9a306 100644
--- a/arch/powerpc/include/asm/setup.h
+++ b/arch/powerpc/include/asm/setup.h

@@ -9,7 +9,7 @@ extern void ppc_printk_progress(char *s, unsigned short hex);
 extern unsigned int rtas_data;
 extern int mem_init_done;	/* set on boot once kmalloc can be called */
 extern int init_bootmem_done;	/* set once bootmem is available */
-extern phys_addr_t memory_limit;
+extern unsigned long long memory_limit;
 extern unsigned long klimit;
 extern void *zalloc_maybe_bootmem(size_t size, gfp_t mask);
 

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 18bdf74..06c8202 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c

@@ -289,8 +289,7 @@ int __init fadump_reserve_mem(void)
 		else
 			memory_limit = memblock_end_of_DRAM();
 		printk(KERN_INFO "Adjusted memory_limit for firmware-assisted"
-				" dump, now %#016llx\n",
-				(unsigned long long)memory_limit);
+				" dump, now %#016llx\n", memory_limit);
 	}
 	if (memory_limit)
 		memory_boundary = memory_limit;

diff --git a/arch/powerpc/kernel/machine_kexec.c b/arch/powerpc/kernel/machine_kexec.c
index 5df7777..4074eff 100644
--- a/arch/powerpc/kernel/machine_kexec.c
+++ b/arch/powerpc/kernel/machine_kexec.c

@@ -165,7 +165,7 @@ void __init reserve_crashkernel(void)
 	if (memory_limit && memory_limit <= crashk_res.end) {
 		memory_limit = crashk_res.end + 1;
 		printk("Adjusted memory limit for crashkernel, now 0x%llx\n",
-		       (unsigned long long)memory_limit);
+		       memory_limit);
 	}
 
 	printk(KERN_INFO "Reserving %ldMB of memory at %ldMB "

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index f191bf0..c82c77d 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c

@@ -78,7 +78,7 @@ static int __init early_parse_mem(char *p)
 		return 1;
 
 	memory_limit = PAGE_ALIGN(memparse(p, &p));
-	DBG("memory limit = 0x%llx\n", (unsigned long long)memory_limit);
+	DBG("memory limit = 0x%llx\n", memory_limit);
 
 	return 0;
 }

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index baaafde..0a8f353 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c

@@ -62,7 +62,7 @@
 
 int init_bootmem_done;
 int mem_init_done;
-phys_addr_t memory_limit;
+unsigned long long memory_limit;
 
 #ifdef CONFIG_HIGHMEM
 pte_t *kmap_pte;

The powerpc kernel doesn't export the memory limit enforced by 'mem='
kernel parameter. This is required for building the ELF header in
kexec-tools to limit the vmcore to capture only the used memory. On
powerpc the kexec-tools depends on the device-tree for memory related
information, unlike /proc/iomem on the x86.

Without this information, the kexec-tools assumes the entire System
RAM and vmcore creates an unnecessarily larger dump.

This patch exports the memory limit, if present, via
chosen/linux,memory-limit
property, so that the vmcore can be limited to the memory limit.

The prom_init seems to export this value in the same node. But doesn't
really
appear there.  Also the memory_limit gets adjusted with the processing of
crashkernel= parameter. This patch makes sure we get the actual limit.

The kexec-tools will use the value to limit the 'end' of the memory
regions.

Tested this patch on ppc64 and ppc32(ppc440) with a kexec-tools
patch by Mahesh.

Signed-off-by: Suzuki K. Poulose <redacted>
Tested-by: Mahesh J. Salgaonkar <redacted>
---

 arch/powerpc/kernel/machine_kexec.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/kernel/machine_kexec.c b/arch/powerpc/kernel/machine_kexec.c
index 4074eff..fa9f6c7 100644
--- a/arch/powerpc/kernel/machine_kexec.c
+++ b/arch/powerpc/kernel/machine_kexec.c

@@ -204,6 +204,12 @@ static struct property crashk_size_prop = {
 	.value = &crashk_size,
 };
 
+static struct property memory_limit_prop = {
+	.name = "linux,memory-limit",
+	.length = sizeof(unsigned long long),
+	.value = &memory_limit,
+};
+
 static void __init export_crashk_values(struct device_node *node)
 {
 	struct property *prop;

@@ -223,6 +229,12 @@ static void __init export_crashk_values(struct device_node *node)
 		crashk_size = resource_size(&crashk_res);
 		prom_add_property(node, &crashk_size_prop);
 	}
+
+	/*
+	 * memory_limit is required by the kexec-tools to limit the
+	 * crash regions to the actual memory used.
+	 */
+	prom_update_property(node, &memory_limit_prop);
 }
 
 static int __init kexec_setup(void)

On Tue, 2012-08-21 at 17:12 +0530, Suzuki K. Poulose wrote:

There are some device-tree nodes, whose values are of type phys_addr_t.
The phys_addr_t is variable sized based on the CONFIG_PHSY_T_64BIT.

Change these to a fixed unsigned long long for consistency.

This patch does the change only for memory_limit.

The following is a list of such variables which need the change:

 1) kernel_end, crashk_size - in arch/powerpc/kernel/machine_kexec.c

 2) (struct resource *)crashk_res.start - We could export a local static
    variable from machine_kexec.c.

Changing the above values might break the kexec-tools. So, I will
fix kexec-tools first to handle the different sized values and then change
 the above.

Suggested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Suzuki K. Poulose <redacted>
---

Breaks the build on some configs (with 32-bit phys_addr_t):

/home/benh/linux-powerpc-test/arch/powerpc/kernel/prom.c: In function
'early_init_devtree':
/home/benh/linux-powerpc-test/arch/powerpc/kernel/prom.c:664:25: error:
comparison of distinct pointer types lacks a cast

I'm fixing that myself this time but please be more careful.

Cheers,
Ben.

On 09/07/2012 07:05 AM, Benjamin Herrenschmidt wrote:

On Tue, 2012-08-21 at 17:12 +0530, Suzuki K. Poulose wrote:

quoted

There are some device-tree nodes, whose values are of type phys_addr_t.
The phys_addr_t is variable sized based on the CONFIG_PHSY_T_64BIT.

Change these to a fixed unsigned long long for consistency.

This patch does the change only for memory_limit.

The following is a list of such variables which need the change:

  1) kernel_end, crashk_size - in arch/powerpc/kernel/machine_kexec.c

  2) (struct resource *)crashk_res.start - We could export a local static
     variable from machine_kexec.c.

Changing the above values might break the kexec-tools. So, I will
fix kexec-tools first to handle the different sized values and then change
  the above.

Suggested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Suzuki K. Poulose <redacted>
---

Breaks the build on some configs (with 32-bit phys_addr_t):

Sorry for that.

/home/benh/linux-powerpc-test/arch/powerpc/kernel/prom.c: In function
'early_init_devtree':
/home/benh/linux-powerpc-test/arch/powerpc/kernel/prom.c:664:25: error:
comparison of distinct pointer types lacks a cast

I'm fixing that myself this time but please be more careful.

Sure. Thanks Ben for fixing that.

Suzuki