* [PATCH 1/1] IBM Z: Fix endianess problem in pid_memory_read
@ 2020-11-19 19:32 Andreas Krebbel
2020-11-20 0:33 ` Mark Wielaard
0 siblings, 1 reply; 3+ messages in thread
From: Andreas Krebbel @ 2020-11-19 19:32 UTC (permalink / raw)
To: elfutils-devel
The cached reads lack the big endian adjustments done in the fallback
path.
Signed-off-by: Andreas Krebbel <krebbel@linux.ibm.com>
---
libdwfl/ChangeLog | 5 +++++
libdwfl/linux-pid-attach.c | 10 +++++++++-
2 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog
index 59ef37aa..ecd87d3a 100644
--- a/libdwfl/ChangeLog
+++ b/libdwfl/ChangeLog
@@ -1,3 +1,8 @@
+2020-11-19 Andreas Krebbel <krebbel@linux.ibm.com>
+
+ * linux-pid-attach.c (pid_memory_read): Shift the upper 4 bytes
+ down on big endian 64 bit targets.
+
2020-11-12 Timm Bäder <tbaeder@redhat.com>
* dwfl_segment_report_module.c (dwfl_segment_report_module): Remove
diff --git a/libdwfl/linux-pid-attach.c b/libdwfl/linux-pid-attach.c
index 3a6af997..b23139d9 100644
--- a/libdwfl/linux-pid-attach.c
+++ b/libdwfl/linux-pid-attach.c
@@ -193,14 +193,22 @@ pid_memory_read (Dwfl *dwfl, Dwarf_Addr addr, Dwarf_Word *result, void *arg)
{
struct __libdwfl_pid_arg *pid_arg = arg;
pid_t tid = pid_arg->tid_attached;
+ Dwfl_Process *process = dwfl->process;
assert (tid > 0);
#ifdef HAVE_PROCESS_VM_READV
if (read_cached_memory (pid_arg, addr, result))
+ {
+#if SIZEOF_LONG == 8
+# if BYTE_ORDER == BIG_ENDIAN
+ if (ebl_get_elfclass (process->ebl) == ELFCLASS32)
+ *result >>= 32;
+# endif
+#endif
return true;
+ }
#endif
- Dwfl_Process *process = dwfl->process;
if (ebl_get_elfclass (process->ebl) == ELFCLASS64)
{
#if SIZEOF_LONG == 8
--
2.25.1
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH 1/1] IBM Z: Fix endianess problem in pid_memory_read
2020-11-19 19:32 [PATCH 1/1] IBM Z: Fix endianess problem in pid_memory_read Andreas Krebbel
@ 2020-11-20 0:33 ` Mark Wielaard
2020-11-20 6:20 ` Andreas Krebbel
0 siblings, 1 reply; 3+ messages in thread
From: Mark Wielaard @ 2020-11-20 0:33 UTC (permalink / raw)
To: Andreas Krebbel; +Cc: elfutils-devel
Hi Andreas,
On Thu, Nov 19, 2020 at 08:32:24PM +0100, Andreas Krebbel via Elfutils-devel wrote:
> The cached reads lack the big endian adjustments done in the fallback
> path.
Thanks for finding this. Did you find this by code inspection or by
having a 31bit binary backtrace on a 64bit system fail?
We actually have a testcase for 31-bit-on-64-bit backtrace
(run-backtrace-native-biarch.sh) but the s390x buildbot worker doesn't
support creating 31bit executables, so the testcase is SKIPPED.
I pushed you patch.
Thanks,
Mark
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH 1/1] IBM Z: Fix endianess problem in pid_memory_read
2020-11-20 0:33 ` Mark Wielaard
@ 2020-11-20 6:20 ` Andreas Krebbel
0 siblings, 0 replies; 3+ messages in thread
From: Andreas Krebbel @ 2020-11-20 6:20 UTC (permalink / raw)
To: Mark Wielaard; +Cc: elfutils-devel
On 20.11.20 01:33, Mark Wielaard wrote:
> Hi Andreas,
>
> On Thu, Nov 19, 2020 at 08:32:24PM +0100, Andreas Krebbel via Elfutils-devel wrote:
>> The cached reads lack the big endian adjustments done in the fallback
>> path.
>
> Thanks for finding this. Did you find this by code inspection or by
> having a 31bit binary backtrace on a 64bit system fail?
>
> We actually have a testcase for 31-bit-on-64-bit backtrace
> (run-backtrace-native-biarch.sh) but the s390x buildbot worker doesn't
> support creating 31bit executables, so the testcase is SKIPPED.
The problem was reported for strace. But then we noticed that the testcase you mentioned fails on Z
currently. It is fixed with the patch.
> I pushed you patch.
Thanks!
Andreas
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-11-19 19:32 [PATCH 1/1] IBM Z: Fix endianess problem in pid_memory_read Andreas Krebbel
2020-11-20 0:33 ` Mark Wielaard
2020-11-20 6:20 ` Andreas Krebbel
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