From: Sandra Loosemore <sandra@codesourcery.com>
To: <gdb-patches@sourceware.org>, Yao Qi <qiyaoltc@gmail.com>
Subject: [patch v2 3/5, nios2] fix register save offset for signal handler trampolines
Date: Thu, 30 Apr 2015 09:03:00 -0000 [thread overview]
Message-ID: <55417801.5070507@codesourcery.com> (raw)
In-Reply-To: <554172F8.2020108@codesourcery.com>
[-- Attachment #1: Type: text/plain, Size: 297 bytes --]
It was requested that I split the patch previously posted here:
https://sourceware.org/ml/gdb-patches/2015-04/msg00907.html
into two parts. This is the first part. I also expanded the comments
to indicate how the register save offset magic number was calculated.
OK to commit now?
-Sandra
[-- Attachment #2: gdb-sigtramp-offset.log --]
[-- Type: text/x-log, Size: 244 bytes --]
2015-04-29 Sandra Loosemore <sandra@codesourcery.com>
gdb/
* nios2-linux-tdep.c (NIOS2_SIGRETURN_TRAMP_ADDR): Define.
(NIOS2_SIGRETURN_REGSAVE_OFFSET): Define.
(nios2_linux_rt_sigreturn_init): Adjust base address of
register save area.
[-- Attachment #3: gdb-sigtramp-offset.patch --]
[-- Type: text/x-patch, Size: 1743 bytes --]
diff --git a/gdb/nios2-linux-tdep.c b/gdb/nios2-linux-tdep.c
index b829569..0a837b0 100644
--- a/gdb/nios2-linux-tdep.c
+++ b/gdb/nios2-linux-tdep.c
@@ -114,7 +114,25 @@ nios2_iterate_over_regset_sections (struct gdbarch *gdbarch,
}
/* Initialize a trad-frame cache corresponding to the tramp-frame.
- FUNC is the address of the instruction TRAMP[0] in memory. */
+ FUNC is the address of the instruction TRAMP[0] in memory.
+
+ This ABI is not documented. It corresponds to rt_setup_ucontext in
+ the kernel arch/nios2/kernel/signal.c file.
+
+ The key points are:
+ - The kernel creates a trampoline at the hard-wired address 0x1044.
+ - The stack pointer points to an object of type struct rt_sigframe.
+ The definition of this structure is not exported from the kernel.
+ The register save area is located at offset 152 bytes (as determined
+ by inspection of the stack contents in the debugger), and the
+ registers are saved as r1-r23, ra, fp, gp, ea, sp.
+
+ This interface was implemented with kernel version 3.19 (the first
+ official mainline kernel). Older unofficial kernel versions used
+ incompatible conventions; we do not support those here. */
+
+#define NIOS2_SIGRETURN_TRAMP_ADDR 0x1044
+#define NIOS2_SIGRETURN_REGSAVE_OFFSET 152
static void
nios2_linux_rt_sigreturn_init (const struct tramp_frame *self,
@@ -122,7 +140,8 @@ nios2_linux_rt_sigreturn_init (const struct tramp_frame *self,
struct trad_frame_cache *this_cache,
CORE_ADDR func)
{
- CORE_ADDR base = func + 41 * 4;
+ CORE_ADDR sp = get_frame_register_unsigned (next_frame, NIOS2_SP_REGNUM);
+ CORE_ADDR base = sp + NIOS2_SIGRETURN_REGSAVE_OFFSET;
int i;
for (i = 0; i < 23; i++)
next prev parent reply other threads:[~2015-04-30 0:33 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-30 0:33 [patch v2 0/5, nios2] unbreak nios2-linux-gnu GDB Sandra Loosemore
2015-04-30 0:36 ` [patch v2 1/5, nios2] revert to using "trap 31" for breakpoints Sandra Loosemore
2015-05-08 9:21 ` Yao Qi
2015-04-30 0:39 ` [patch v2 2/5, nios2] use PTRACE_GETREGSET/SETREGSET in gdbserver Sandra Loosemore
2015-05-08 9:23 ` Yao Qi
2015-04-30 9:03 ` Sandra Loosemore [this message]
2015-05-08 9:31 ` [patch v2 3/5, nios2] fix register save offset for signal handler trampolines Yao Qi
2015-04-30 9:08 ` [patch v2 4/5, nios2] work around issues with unwritable signal handler trampoline code Sandra Loosemore
2015-05-08 11:08 ` Yao Qi
2015-04-30 12:05 ` [patch v2 5/5, nios2] add NEWS entry for ABI change Sandra Loosemore
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