[RFC PATCH] kernel/kallsyms.c: only show legal kernel symbol

[Ming Lei]

Address of non-module kernel symbol should always be located
from CONFIG_PAGE_OFFSET on, so only show these legal kernel
symbols in /proc/kallsyms.

On ARM, some symbols(see below) may drop in relocatable code, so
perf can't parse kernel symbols any more from /proc/kallsyms, this
patch fixes the problem.

	00000000 t __vectors_start
	00000020 A cpu_v7_suspend_size
	00001000 t __stubs_start
	00001004 t vector_rst
	00001020 t vector_irq
	000010a0 t vector_dabt
	00001120 t vector_pabt
	000011a0 t vector_und
	00001220 t vector_addrexcptn
	00001224 t vector_fiq
	00001224 T vector_fiq_offset

The issue can be fixed in scripts/kallsyms.c too, but looks this
approach is easier.

Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Chen Gang <gang.chen@xxxxxxxxxxx>
Signed-off-by: Ming Lei <tom.leiming@xxxxxxxxx>
---
 kernel/kallsyms.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 3127ad5..184f271 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -543,7 +543,7 @@ static int s_show(struct seq_file *m, void *p)
 					tolower(iter->type);
 		seq_printf(m, "%pK %c %s\t[%s]\n", (void *)iter->value,
 			   type, iter->name, iter->module_name);
-	} else
+	} else if (iter->value >= CONFIG_PAGE_OFFSET)
 		seq_printf(m, "%pK %c %s\n", (void *)iter->value,
 			   iter->type, iter->name);
 	return 0;
-- 
1.7.9.5

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