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Subject[PATCH 1/1] exception/stackdepot: add irqentry section in case of STACKDEPOT
Date
As of now if CONFIG_FUNCTION_GRAPH_TRACER is disabled some functions
like gic_handle_irq will not be added in irqentry text section.

which leads to adding more stacks in stackdepot as frames below IRQ
will not be filtered with filter_irq_stack() function.

checked with debug interface for satckdepot:
https://lkml.org/lkml/2017/11/22/242

e.g. (ARM)
stack count 23188 backtrace
prep_new_page+0x14c/0x160
get_page_from_freelist+0x1258/0x1350
...
__handle_domain_irq+0x1ac/0x4ac
gic_handle_irq+0x44/0x80
__irq_svc+0x5c/0x98
__slab_alloc.constprop.0+0x84/0xac
__kmalloc+0x31c/0x340
sf_malloc+0x14/0x18

and for same _irq_svc there were 25000 calls which was causing
memory pressure of 2MB more on satckdepot, which will keep increasing.

Before patch memory consumption on ARM target after 2 hours:
Memory consumed by Stackdepot:3600 KB

After change:
============
Memory consumed by Stackdepot:1744 KB

prep_new_page+0x14c/0x160
get_page_from_freelist+0x2e4/0x1350
...
__handle_domain_irq+0x1ac/0x4ac
gic_handle_irq+0x44/0x80

^^^^^ no frames below this.

Signed-off-by: Maninder Singh <maninder1.s@samsung.com>
Signed-off-by: Vaneet Narang <v.narang@samsung.com>
---
arch/arm/include/asm/exception.h | 2 +-
arch/arm64/include/asm/exception.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/include/asm/exception.h b/arch/arm/include/asm/exception.h
index 58e039a851af..3f4534cccc0f 100644
--- a/arch/arm/include/asm/exception.h
+++ b/arch/arm/include/asm/exception.h
@@ -10,7 +10,7 @@

#include <linux/interrupt.h>

-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_STACKDEPOT)
#define __exception_irq_entry __irq_entry
#else
#define __exception_irq_entry
diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h
index 339477dca551..ef2581b63405 100644
--- a/arch/arm64/include/asm/exception.h
+++ b/arch/arm64/include/asm/exception.h
@@ -13,7 +13,7 @@

#include <linux/interrupt.h>

-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_STACKDEPOT)
#define __exception_irq_entry __irq_entry
#else
#define __exception_irq_entry __kprobes
--
2.17.1
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