Re: [pcre-dev] Fwd: Bug#840354: src:pcre3: FTBFS on powerpc …

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Autor: Zoltán Herczeg
Data:  
A: Matthew Vernon
CC: pcre-dev
Assumpte: Re: [pcre-dev] Fwd: Bug#840354: src:pcre3: FTBFS on powerpc (G4 CPU)
Hi Matthew,

several PCRE2 improvements were migrated to PCRE in 8.39. That might be the cause of the issue. However from the report it is difficult to tell what is happening.

>Program received signal SIGILL, Illegal instruction.
>0xb7faf0ec in ?? ()
>=> 0xb7faf0ec:  li      r3,-1


load immediate is a basic instruction.

>=> 0xb7fe5008:  mflr    r0


This is the way to return from a function call.

>=> 0xb7faf060:  lwz     r28,8(r5)

Load word also a basic instruction.

Is it possible that the SIGILL is imprecise and the previous instruction is the invalid one? E.g:

disassemble addr-16,addr+16

Or perhaps execution rights are not enabled for that instruction? 008, 060 is somewhere at the beginning of a 4K page, perhaps the page has invalid rights (or some security enhancement disallow RWX)?

Regards,
Zoltan

Matthew Vernon <matthew@???> írta:
>Hi,
>
>I've had the following bug report submitted; if the submitter is correct
>(which seems likely, but I don't have a G4 powerpc box to test on), then
>the jit code in 8.39 is using G5 instructions inappropriately (where the
>8.38 code didn't).
>
>Obviously, I could just disable jit for this architecture, but I'd
>rather avoid it if possible...
>
>Regards,
>
>Matthew
>
>-------- Forwarded Message --------
>Subject: Bug#840354: src:pcre3: FTBFS on powerpc (G4 CPU)
>Resent-Date: Mon, 10 Oct 2016 20:39:06 +0000
>Resent-From: Christoph Biedl <debian.axhn@???>
>Resent-To: debian-bugs-dist@???
>Resent-CC: Matthew Vernon <matthew@???>
>Date: Mon, 10 Oct 2016 22:37:40 +0200
>From: Christoph Biedl <debian.axhn@???>
>Reply-To: Christoph Biedl <debian.axhn@???>,
>840354@???
>To: Debian Bug Tracking System <submit@???>
>
>Package: src:pcre3
>Version: 2:8.39-2
>Severity: important
>Usertag: debian-powerpc@???
>
>Dear Maintainer,
>
>Rebuilding syslog-ng 3.7.3-3 on a PowerMac G4 failed with SIGILL,
>debugging led to libpcre, and finally rebuilding src:pcre3 itself
>fails with very similar symptoms:
>
>(...)
>/usr/bin/make  check-TESTS
>make[3]: Entering directory '/tmp/pcre3/pcre3-8.39'
>make[4]: Entering directory '/tmp/pcre3/pcre3-8.39'
>./test-driver: line 107: 12195 Illegal instruction     "$@" > $log_file 2>&1
>FAIL: pcre_jit_test
>PASS: pcrecpp_unittest
>PASS: pcre_scanner_unittest
>(...)

>
>The failing program is .libs/lt-pcre_jit_test. Using gdb is no help at
>all, the failures happen at a different point every invocation:
>
>Program received signal SIGILL, Illegal instruction.
>0xb7faf0ec in ?? ()
>(gdb) bt
>#0  0xb7faf0ec in ?? ()
>#1  0x1ff30718 in ?? ()
>#2  0x1ff30718 in ?? ()
>#3  0x1ff0adf4 in ?? ()
>#4  0x200061c8 in ?? ()
>#5  0x20004a3c in ?? ()
>#6  0x1fc97274 in ?? ()
>#7  0x1fc9747c in ?? ()
>#8  0x00000000 in ?? ()
>(gdb) disassemble 0xb7faf0ec,0xb7faf0ff
>Dump of assembler code from 0xb7faf0ec to 0xb7faf0ff:
>=> 0xb7faf0ec:  li      r3,-1
>   0xb7faf0f0:  addi    r5,r30,6
>   0xb7faf0f4:  cmplw   cr1,r5,r29
>   0xb7faf0f8:  bgt     cr1,0xb7faf1b8
>   0xb7faf0fc:  lwz     r5,36(r1)

>
>Program received signal SIGILL, Illegal instruction.
>0xb7fe5008 in ?? ()
>(gdb) bt
>#0  0xb7fe5008 in ?? ()
>#1  0x1ffb8b80 in ?? ()
>#2  0x1ff91820 in ?? ()
>#3  0x20006110 in ?? ()
>#4  0x20004a3c in ?? ()
>#5  0x1fc97274 in ?? ()
>#6  0x1fc9747c in ?? ()
>#7  0x00000000 in ?? ()
>(gdb) disassemble 0xb7fe5008,0xb7fe5020
>Dump of assembler code from 0xb7fe5008 to 0xb7fe5020:
>=> 0xb7fe5008:  mflr    r0
>   0xb7fe500c:  stw     r31,-4(r1)
>   0xb7fe5010:  stw     r30,-8(r1)
>   0xb7fe5014:  stw     r29,-12(r1)
>   0xb7fe5018:  stw     r28,-16(r1)
>   0xb7fe501c:  stw     r27,-20(r1)

>
>Program received signal SIGILL, Illegal instruction.
>0xb7faf060 in ?? ()
>(gdb) bt
>#0  0xb7faf060 in ?? ()
>#1  0x1ff30718 in ?? ()
>#2  0x1ff30718 in ?? ()
>#3  0x1ff0adf4 in ?? ()
>#4  0x200061c8 in ?? ()
>#5  0x20004a3c in ?? ()
>#6  0x1fc97274 in ?? ()
>#7  0x1fc9747c in ?? ()
>#8  0x00000000 in ?? ()
>(gdb) disassemble 0xb7faf060,0xb7faf070
>Dump of assembler code from 0xb7faf060 to 0xb7faf070:
>=> 0xb7faf060:  lwz     r28,8(r5)
>   0xb7faf064:  addi    r3,r3,1
>   0xb7faf068:  stw     r3,32(r1)
>   0xb7faf06c:  b       0xb7faf0cc

>
>
>My last rebuild of syslog-ng in July, using pcre3 version 2:8.38-3.1,
>succeded. Therefore I guess it's the changes between 8.38 and 8.39.
>Very likely this was introduced by the changes in the ppc_jit code
>which unfortunately I was unable to understand.
>
>Disabling jit for powerpc using the following patch:
>
>--- pcre3-8.39.orig/sljit/sljitConfigInternal.h
>+++ pcre3-8.39/sljit/sljitConfigInternal.h
>@@ -135,11 +135,7 @@
> #elif defined(__ppc64__) || defined(__powerpc64__) ||
>defined(_ARCH_PPC64) || (defined(_POWER) && defined(__64BIT__))
> #define SLJIT_CONFIG_PPC_64 1
> #elif defined(__ppc__) || defined(__powerpc__) || defined(_ARCH_PPC) ||
>defined(_ARCH_PWR) || defined(_ARCH_PWR2) || defined(_POWER)
>-# ifndef __NO_FPRS__
>-# define SLJIT_CONFIG_PPC_32 1
>-# else
> # define SLJIT_CONFIG_UNSUPPORTED 1
>-# endif
> #elif defined(__mips__) && !defined(_LP64)
> #define SLJIT_CONFIG_MIPS_32 1
> #elif defined(__mips64)
>
>resulted in a successful pcre3 build, and using the created packages
>also syslog-ng passes the failing test again.
>
>
>So I'm asking you to bring this upstream to sort out how the breakage
>was introduced. From other bug reports I guess the created code uses
>G5 instructions; the Debian powerpc buildds didn't notice as they
>actually are such newer boxes.
>
>As a hopefully temporary workaround you could disable jit for powerpc,
>of course a the cost of a performance penalty.
>
>    Christoph

>
>-- System Information:
>Debian Release: stretch/sid
> APT prefers testing
> APT policy: (500, 'testing')
>Architecture: powerpc (ppc)
>
>Kernel: Linux 4.4.23
>Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968)
>Shell: /bin/sh linked to /bin/dash
>Init: unable to detect
>
>
>
>--
>## List details at https://lists.exim.org/mailman/listinfo/pcre-dev