[PATCH v2 8/9] arm: Add RAMOOPS memory area

[Markus Pargmann <mpa@pengutronix.de>]

RAMOOPS is a driver that uses a reserved static memory region to store
the data from the last panic or boot. This helps to debug crashes at the
next boot while preserving the boot messages.

To guarantee a memory area that is not altered by barebox or the kernel,
this area is located at the end of the RAM right after barebox and
before the STACK. This ensures that changing barebox sizes do not
interfere with RAMOOPS.

Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
---
 arch/arm/cpu/start.c               |  6 ++++++
 arch/arm/include/asm/barebox-arm.h | 14 +++++++++++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/arm/cpu/start.c b/arch/arm/cpu/start.c
index 4ad64b61e86a..d03d1edfaf18 100644
--- a/arch/arm/cpu/start.c
+++ b/arch/arm/cpu/start.c
@@ -118,6 +118,12 @@ static inline unsigned long arm_mem_boarddata(unsigned long membase,
 	return mem;
 }
 
+unsigned long arm_mem_ramoops_get(void)
+{
+	return arm_mem_ramoops(0, arm_stack_top);
+}
+EXPORT_SYMBOL_GPL(arm_mem_ramoops_get);
+
 static int barebox_memory_areas_init(void)
 {
 	unsigned long start = arm_head_bottom;
diff --git a/arch/arm/include/asm/barebox-arm.h b/arch/arm/include/asm/barebox-arm.h
index 8d52882981f1..67133265d155 100644
--- a/arch/arm/include/asm/barebox-arm.h
+++ b/arch/arm/include/asm/barebox-arm.h
@@ -122,11 +122,23 @@ static inline unsigned long arm_mem_early_malloc_end(unsigned long membase,
 	return arm_mem_ttb(membase, endmem);
 }
 
+static inline unsigned long arm_mem_ramoops(unsigned long membase,
+					    unsigned long endmem)
+{
+	endmem = arm_mem_ttb(membase, endmem);
+#ifdef CONFIG_FS_PSTORE_RAMOOPS
+	endmem -= CONFIG_FS_PSTORE_RAMOOPS_SIZE;
+	endmem &= ~(SZ_4K - 1); /* Align to 4K */
+#endif
+
+	return endmem;
+}
+
 static inline unsigned long arm_mem_barebox_image(unsigned long membase,
 						  unsigned long endmem,
 						  unsigned long size)
 {
-	endmem = arm_mem_ttb(membase, endmem);
+	endmem = arm_mem_ramoops(membase, endmem);
 
 	if (IS_ENABLED(CONFIG_RELOCATABLE)) {
 		endmem -= size;
-- 
2.6.2


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