Your message dated Sat, 5 Apr 2025 19:29:09 +0200
with message-id
<waqc2xuh6t6nmmz3pec5ymyc3vlguzmqci3jyqwlgoi2yrpd75@mql3deszjehx>
and subject line Re: Bug#979108: memtool: 64 bit memory reads may be split on
32 bit systems
has caused the Debian Bug report #979108,
regarding memtool: 64 bit memory reads may be split on 32 bit systems
to be marked as done.
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--
979108: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=979108
Debian Bug Tracking System
Contact [email protected] with problems
--- Begin Message ---
Package: memtool
Severity: normal
Tags: upstream patch
Hello,
I tried memtool on a 32 bit ARM system, and the supposedly 64 bit reads
with the "-q" option are done by 2 separate 32 bit "ldr" instructions.
Adding a volatile qualifier to the pointers accessing the memory could
convince gcc to generate a single "ldrd" instruction instead, which uses
a 64 bit memory transfer. See below a proposed patch. Adding volatile to all
4 cases may be an overkill, but can't hurt. Cheers,
Gergely Peli
========
--- memtool-2016.10.0.orig/memtool.c
+++ memtool-2016.10.0/memtool.c
@@ -152,24 +152,24 @@ static int memory_display(const void *ad
for (i = 0; i < linebytes; i += width) {
if (width == 8) {
uint64_t res;
- res = (*uqp++ = *((uint64_t *)addr));
+ res = (*uqp++ = *((volatile uint64_t *)addr));
if (swab)
res = swab64(res);
count -= printf(" %016" PRIx64, res);
} else if (width == 4) {
uint32_t res;
- res = (*uip++ = *((uint *)addr));
+ res = (*uip++ = *((volatile uint *)addr));
if (swab)
res = swab32(res);
count -= printf(" %08" PRIx32, res);
} else if (width == 2) {
uint16_t res;
- res = (*usp++ = *((ushort *)addr));
+ res = (*usp++ = *((volatile ushort *)addr));
if (swab)
res = swab16(res);
count -= printf(" %04" PRIx16, res);
} else {
- count -= printf(" %02x", (*ucp++ = *((u_char
*)addr)));
+ count -= printf(" %02x", (*ucp++ = *((volatile
u_char *)addr)));
}
addr += width;
offs += width;
========
PS: the below specs are not for the tested system.
-- System Information:
Debian Release: 8.2
APT prefers testing
APT policy: (500, 'testing')
Architecture: amd64 (x86_64)
Foreign Architectures: i386
Kernel: Linux 4.19.0-8-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_DK.UTF-8, LC_CTYPE=en_DK.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: sysvinit (via /sbin/init)
--- End Message ---
--- Begin Message ---
Hello,
this bug doesn't affect memtool in oldstable and newer, so I close it.
Best regards
Uwe
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--- End Message ---
