From: Tiejun Chen <tiejun.chen@windriver.com>
To: <benh@kernel.crashing.org>
Cc: <jason.wessel@windriver.com>, <linuxppc-dev@lists.ozlabs.org>,
<linux-kernel@vger.kernel.org>
Subject: [PATCH 3/3] kgdb/kgdbts: support ppc64
Date: Thu, 25 Oct 2012 14:43:30 +0800 [thread overview]
Message-ID: <1351147410-17452-3-git-send-email-tiejun.chen@windriver.com> (raw)
In-Reply-To: <1351147410-17452-1-git-send-email-tiejun.chen@windriver.com>
We can't look up the address of the entry point of the function simply
via that function symbol for all architectures.
For PPC64 ABI, actually there is a function descriptors structure.
A function descriptor is a three doubleword data structure that contains
the following values:
* The first doubleword contains the address of the entry point of
the function.
* The second doubleword contains the TOC base address for
the function.
* The third doubleword contains the environment pointer for
languages such as Pascal and PL/1.
So we should call a wapperred dereference_function_descriptor() to get
the address of the entry point of the function.
Note this is also safe for other architecture after refer to
"include/asm-generic/sections.h" since:
dereference_function_descriptor(p) always is (p) if without arched definition.
Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
---
drivers/misc/kgdbts.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/misc/kgdbts.c b/drivers/misc/kgdbts.c
index 3aa9a96..4799e1f 100644
--- a/drivers/misc/kgdbts.c
+++ b/drivers/misc/kgdbts.c
@@ -103,6 +103,7 @@
#include <linux/delay.h>
#include <linux/kthread.h>
#include <linux/module.h>
+#include <asm/sections.h>
#define v1printk(a...) do { \
if (verbose) \
@@ -222,6 +223,7 @@ static unsigned long lookup_addr(char *arg)
addr = (unsigned long)do_fork;
else if (!strcmp(arg, "hw_break_val"))
addr = (unsigned long)&hw_break_val;
+ addr = (unsigned long )dereference_function_descriptor((void *)addr);
return addr;
}
--
1.7.9.5
next prev parent reply other threads:[~2012-10-25 6:44 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-25 6:43 [PATCH 1/3] powerpc/book3e: load critical/machine/debug exception stack Tiejun Chen
2012-10-25 6:43 ` [PATCH 2/3] powerpc/book3e: support kgdb for kernel space Tiejun Chen
2012-10-25 6:43 ` Tiejun Chen [this message]
2012-12-18 22:10 ` [PATCH 1/3] powerpc/book3e: load critical/machine/debug exception stack Tabi Timur-B04825
2012-12-20 9:14 ` tiejun.chen
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