Hello, We have been using Linaro GCC 5.x[1] and valgrind.
When the optimizer is turned on valgrind complains about writes beyond
the current stack pointer. With the optimizer off, the problem report
goes away.
I have my own conclusion about what is going on but I won't bias you
with it. Here are the facts:
All files and logs attached as 10K tar.gz if it survives this maillist.
test.c:
#include <stdio.h>
int main(int argc,char** argv)
{
int i;
for (i = 1; i < argc; i++) {
printf("argument is %s\n", argv[i]);
}
return 0;
}
$ arm-linux-gnueabihf-gcc -march=armv7ve -marm -mfpu=neon \
-mfloat-abi=hard -mcpu=cortex-a15 -O2 -g \
-o test-fail test.c
$ valgrind --leak-resolution=high --track-origins=yes \
--trace-children=yes --leak-check=full --error-limit=no \
./test-fail arg1 arg2 arg3
==20011== Memcheck, a memory error detector
==20011== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==20011== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==20011== Command: ./test-fail arg1 arg2 arg3
==20011==
==20011== Invalid write of size 4
==20011== at 0x10300: main (test.c:4)
==20011== Address 0xbdbfcb58 is on thread 1's stack
==20011== 24 bytes below stack pointer
==20011==
000102f8 <main>:
102f8: e3500001 cmp r0, #1
102fc: da000014 ble 10354 <main+0x5c>
10300: e16d41f8 strd r4, [sp, #-24]! ; 0xffffffe8
^^^^^^^^ Complaint is here
10304: e1a05001 mov r5, r1
10308: e3a04001 mov r4, #1
1030c: e1cd60f8 strd r6, [sp, #8]
10310: e300748c movw r7, #1164 ; 0x48c
10314: e1a06000 mov r6, r0
10318: e3407001 movt r7, #1
1031c: e58d8010 str r8, [sp, #16]
10320: e58de014 str lr, [sp, #20]
10324: e2844001 add r4, r4, #1
10328: e5b51004 ldr r1, [r5, #4]!
1032c: e1a00007 mov r0, r7
10330: ebffffe4 bl 102c8 <printf@plt>
10334: e1560004 cmp r6, r4
10338: 1afffff9 bne 10324 <main+0x2c>
1033c: e1cd40d0 ldrd r4, [sp]
10340: e3a00000 mov r0, #0
10344: e1cd60d8 ldrd r6, [sp, #8]
10348: e59d8010 ldr r8, [sp, #16]
1034c: e28dd014 add sp, sp, #20
10350: e49df004 pop {pc} ; (ldr pc, [sp], #4)
10354: e3a00000 mov r0, #0
10358: e12fff1e bx lr
Without the optimizer, the code looks different and valgrind does not
issue any errors.
000103d8 <main>:
103d8: e52db008 str fp, [sp, #-8]!
^^^^^^^ Valgrind does not complain about this
103dc: e58de004 str lr, [sp, #4]
103e0: e28db004 add fp, sp, #4
103e4: e24dd010 sub sp, sp, #16
103e8: e50b0010 str r0, [fp, #-16]
103ec: e50b1014 str r1, [fp, #-20] ; 0xffffffec
103f0: e3a03001 mov r3, #1
103f4: e50b3008 str r3, [fp, #-8]
103f8: ea00000b b 1042c <main+0x54>
103fc: e51b3008 ldr r3, [fp, #-8]
10400: e1a03103 lsl r3, r3, #2
10404: e51b2014 ldr r2, [fp, #-20] ; 0xffffffec
10408: e0823003 add r3, r2, r3
1040c: e5933000 ldr r3, [r3]
10410: e1a01003 mov r1, r3
10414: e30004a4 movw r0, #1188 ; 0x4a4
10418: e3400001 movt r0, #1
1041c: ebffffa9 bl 102c8 <printf@plt>
10420: e51b3008 ldr r3, [fp, #-8]
10424: e2833001 add r3, r3, #1
10428: e50b3008 str r3, [fp, #-8]
1042c: e51b2008 ldr r2, [fp, #-8]
10430: e51b3010 ldr r3, [fp, #-16]
10434: e1520003 cmp r2, r3
10438: baffffef blt 103fc <main+0x24>
1043c: e3a03000 mov r3, #0
10440: e1a00003 mov r0, r3
10444: e24bd004 sub sp, fp, #4
10448: e59db000 ldr fp, [sp]
1044c: e28dd004 add sp, sp, #4
10450: e49df004 pop {pc} ; (ldr pc, [sp], #4)
[1] 5.3-2016.02 for Yocto-project and cross-compile
5.2 on the ARM target "since Linaro hasn’t yet fixed building 5.3 from
recipes yet."
Both versions give the same results for this test program.
----------------
William A. Mills
Chief Technologist, Open Solutions, SDO
Texas Instruments, Inc.
20450 Century Blvd
Germantown MD 20878
240-643-0836
valtest.tar.gz
Description: application/gzip
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