Re: [cip-dev] ldconfig segfault on RZ/Five was Re: Preparing isar-cip-core for RZ/Five

[Pavel Machek <pavel@denx.de>]

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Hi!

> > On 10/12/2022 11:50 AM CEST Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> wrote:
> > I did a quick test with the patches pointed by Florian but unfortunately ldconfig still fails.
> 
> I did some experiments on RZ/Five with this issue, and I'm almost positive that there is something wrong (or doesn't work as documented) with the icache handling on this SoC.
> 
> 1. The issue only affects non-PIE executables (there are very few of those, basically just ldconfig, gcc, cpp and gcov* on the Debian system), and it occurs very early during the execution of the program. According to the datasheet, the cache on the ax45mp-1c core is virtually indexed, so it is unlikely that a PIE executable will ever hit anything in the cache when newly loaded, but it is much more likely with non-PIE executables.
>

This is very good observation. Thanks!

And indeed it looks like _any_ non-PIE executable fails. See:

root@smarc-rzfive:/my# cat mytest.c 
#include <stdio.h>

void main(void) { printf("ahoj svete\n"); } 
root@smarc-rzfive:/my# clang mytest.c -fno-pie -static
mytest.c:3:1: warning: return type of 'main' is not 'int' [-Wmain-return-type]
void main(void) { printf("ahoj svete\n"); } 
^
mytest.c:3:1: note: change return type to 'int'
void main(void) { printf("ahoj svete\n"); } 
^~~~
int
1 warning generated.
root@smarc-rzfive:/my# ./a.out 
[  279.010424] a.out[214]: unhandled signal 11 code 0x1 at 0xffffff8c38bd1524


(-O3 -g might be useful to add to clang command line).

Then you can

b _dl_discover_osversion
run

(gdb) disassemble /r
Dump of assembler code for function _dl_discover_osversion:
   0x000000000002538a <+0>:     41 71   addi    sp,sp,-496
   0x000000000002538c <+2>:     a8 00   addi    a0,sp,72
   0x000000000002538e <+4>:     86 f7   sd      ra,488(sp)
   0x0000000000025390 <+6>:     a2 f3   sd      s0,480(sp)
   0x0000000000025392 <+8>:     a6 ef   sd      s1,472(sp)
   0x0000000000025394 <+10>:    ca eb   sd      s2,464(sp)
=> 0x0000000000025396 <+12>:    ef 60 a1 5c     jal     ra,0x3b960 <uname>
   0x000000000002539a <+16>:    93 05 a1 0c     addi    a1,sp,202
   0x000000000002539e <+20>:    49 e5   bnez    a0,0x25428 <_dl_discover_osversion+158>
   0x00000000000253a0 <+22>:    81 48   li      a7,0
   0x00000000000253a2 <+24>:    01 45   li      a0,0
   0x00000000000253a4 <+26>:    25 48   li      a6,9
   0x00000000000253a6 <+28>:    13 03 e0 02     li      t1,46

It clearly tries to call uname, which.. it should, according to the
source code. But somehow it ends up in completely different function:

(gdb) stepi

Program received signal SIGILL, Illegal instruction.
0x000000000003b2fe in wcsrtombs ()

Best regards,
							Pavel
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