Hi Arun,
thanks for your comments!
On 08/06/2011 09:54 PM, Arun Sharma wrote:
On Wed, Aug 3, 2011 at 5:12 AM, Ken Werner<[email protected]> wrote:
Use the dh_iterate_phdr callback in Gfind_proc_info-lsb.c to find the ARM
specific unwind tables rather than doing it on our own at the unw_init_local.
You probably meant dl_iterate_phdr?
Yes, exactly - good catch.
I'll fix the commit comment.
index 6c94f05..584f392 100644
--- a/include/libunwind-dynamic.h
+++ b/include/libunwind-dynamic.h
@@ -75,7 +75,8 @@ typedef enum
{
UNW_INFO_FORMAT_DYNAMIC, /* unw_dyn_proc_info_t */
UNW_INFO_FORMAT_TABLE, /* unw_dyn_table_t */
- UNW_INFO_FORMAT_REMOTE_TABLE /* unw_dyn_remote_table_t */
+ UNW_INFO_FORMAT_REMOTE_TABLE, /* unw_dyn_remote_table_t */
+ UNW_INFO_FORMAT_ARM_EXIDX /* ARM specific unwind info */
Could you add a reference to the doc that describes ARM_EXIDX some place?
> Not sure if this is the right one.
>
http://infocenter.arm.com/help/topic/com.arm.doc.ihi0044d/IHI0044D_aaelf.pdf
There is a document dedicated to the ARM exception handling ABI. What
about adding someting like the comment below to src/arm/Gex_tables.c?
/* This file contains functionality for parsing and interpreting the ARM
specific unwind information. Documentation about the exception handling
ABI for the ARM architecture can be found at:
http://infocenter.arm.com/help/topic/com.arm.doc.ihi0038a/IHI0038A_ehabi.pdf
*/
diff --git a/src/dwarf/Gfind_proc_info-lsb.c b/src/dwarf/Gfind_proc_info-lsb.c
index d65342c..5c1931d 100644
--- a/src/dwarf/Gfind_proc_info-lsb.c
+++ b/src/dwarf/Gfind_proc_info-lsb.c
@@ -57,6 +57,9 @@ struct callback_data
int single_fde; /* did we find a single FDE? (vs. a table) */
unw_dyn_info_t di; /* table info (if single_fde is false) */
unw_dyn_info_t di_debug; /* additional table info for .debug_frame */
+#if UNW_TARGET_ARM
+ unw_dyn_info_t di_arm; /* additional table info for .ARM.exidx */
+#endif
};
I'm a bit concerned about the arch-specific stuff getting added to
callback_data. What are the minimal arch specific hooks you need to
get this to work without an #ifdef UNW_TARGET_ARM? Something along the
lines of:
unw_dyn_info_t *di_tdep;
I'm not sure I can follow. I agree that these ifdefs aren't very nice
but what are the alternatives given the design of the libunwind API? The
libunwind ARM backend could define its own tdep_find_proc_info but
almost all of the code would be identical. It would walk the program
headers using dl_iterate_phdr to collect the unw_dyn_info_t information
and then call tdep_search_unwind_table to fill unw_proc_info_t.
@@ -783,14 +809,21 @@ dwarf_find_proc_info (unw_addr_space_t as, unw_word_t ip,
/* search the table: */
if (cb_data.di.format != -1)
- ret = dwarf_search_unwind_table (as, ip,&cb_data.di,
- pi, need_unwind_info, arg);
+ ret = tdep_search_unwind_table (as, ip,&cb_data.di,
+ pi, need_unwind_info, arg);
else
ret = -UNW_ENOINFO;
+#if UNW_TARGET_ARM
+ if (ret == -UNW_ENOINFO&& cb_data.di_arm.format != -1)
+ ret = tdep_search_unwind_table (as, ip,&cb_data.di_arm, pi,
+ need_unwind_info, arg);
+#endif
+
if (ret == -UNW_ENOINFO&& cb_data.di_debug.format != -1)
- ret = dwarf_search_unwind_table (as, ip,&cb_data.di_debug, pi,
- need_unwind_info, arg);
+ ret = tdep_search_unwind_table (as, ip,&cb_data.di_debug, pi,
+ need_unwind_info, arg);
+
return ret;
I'd like to minimize the number of calls between dwarf_find_proc_info
and target dependent code. Two sounds better than three.
My understanding of what tdep_search_unwind_table does is that it gets
the IP and unw_dyn_info as its input and does whatever is necessary to
find the corresponding unwind info to be stored in unw_proc_info. Since
there is no .eh_frame information on ARM the cb_data.di.format will be
-1, no call will be made to tdep_search_unwind_table which leaves us
with a max of 2 calls for ARM as well.
Thanks,
Ken
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