Re: MIPS: relocation issue

[Peter Mamonov <pmamonov@gmail.com>]

On Tue, Jan 28, 2020 at 12:03:35PM +0100, Oleksij Rempel wrote:
> 
> 
> On 28.01.20 11:49, Peter Mamonov wrote:
> > Hi Oleksij,
> > 
> > Below you will find the patch, which adds the `whereami` command. The command
> > prints several addresses belonging to code, data, bss, heap and stack areas.
> > I've run it on qemu/malta with relocations enabled and disabled as per Antony's
> > mail. Output comparison shows that only the stack is relocated. Looks like
> > relocation doesn't work as expected. Also note that the stack was relocated
> > from the uncached KSEG1 to the cached KSEG0 segment, which is inconsistent at
> > least.
> > 
> 
> ACK. The patch "MIPS: remove .bss to __rel_start overlay" should fix it. Please test :)

Ok, will report back soon.

> 
> > Relocation enabled:
> > 
> > 	barebox@qemu malta:/ whereami
> > 	code   @ a0829bcc (a0829bc0)
> > 	data   @ a085f3c0
> > 	bss    @ a0861ae0
> > 	heap   @ a0428c38
> > 	stack  @ 8fb8fd50
> > 	barebox@qemu malta:/ version
> > 
> > 	barebox 2020.01.0-00104-gfe12ba2776 #3 Tue Jan 28 13:34:06 MSK 2020
> > 
> > 
> > Relocation disabled:
> > 
> > 	barebox@qemu malta:/ whereami
> > 	code   @ a0829bcc (a0829bc0)
> > 	data   @ a085f1e0
> > 	bss    @ a0861900
> > 	heap   @ a0428c38
> > 	stack  @ a03ffd50
> 
> This functionality is available with command iomem.

At the moment iomem's output is inconsistent in case of the stack at least:

barebox@qemu malta:/ iomem
...
  0xa0000000 - 0xafffffff (size 0x10000000) kseg1_ram0
    0xa03f9000 - 0xa03fffff (size 0x00007000) stack <<<<<<<<<<<<<<<<<<< !!!!
    0xa0400000 - 0xa07fffff (size 0x00400000) malloc space
    0xa0800000 - 0xa085ae9f (size 0x0005aea0) barebox
    0xa085aea0 - 0xa085fadf (size 0x00004c40) barebox data
    0xa085fae0 - 0xa0863bdf (size 0x00004100) bss
barebox@qemu malta:/ whereami
code   @ a0829bcc (a0829bc0)
data   @ a085f3c0
bss    @ a0861ae0
heap   @ a0429518
stack  @ 8fb8fd50  <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< !!!
barebox@qemu malta:/ 

Regards,
Peter

> > ---
> >   commands/Kconfig    |  5 +++++
> >   commands/Makefile   |  1 +
> >   commands/whereami.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
> >   3 files changed, 51 insertions(+)
> >   create mode 100644 commands/whereami.c
> > 
> > diff --git a/commands/Kconfig b/commands/Kconfig
> > index add0d26ee9..a660e09db4 100644
> > --- a/commands/Kconfig
> > +++ b/commands/Kconfig
> > @@ -2217,6 +2217,11 @@ config CMD_UBSAN
> >   	  This is a test command for the undefined behavior sanitizer.
> >   	  It triggers various undefined behavior, and detect it.
> > +config CMD_WHEREAMI
> > +	tristate "whereami"
> > +	depends on MIPS
> > +	default y
> > +
> >   # end Miscellaneous commands
> >   endmenu
> > diff --git a/commands/Makefile b/commands/Makefile
> > index 8e8c449bc1..dfa3d6e447 100644
> > --- a/commands/Makefile
> > +++ b/commands/Makefile
> > @@ -128,6 +128,7 @@ obj-$(CONFIG_CMD_NAND_BITFLIP)	+= nand-bitflip.o
> >   obj-$(CONFIG_CMD_SEED)		+= seed.o
> >   obj-$(CONFIG_CMD_IP_ROUTE_GET)  += ip-route-get.o
> >   obj-$(CONFIG_CMD_UBSAN)		+= ubsan.o
> > +obj-$(CONFIG_CMD_WHEREAMI)	+= whereami.o
> >   UBSAN_SANITIZE_ubsan.o := y
> > diff --git a/commands/whereami.c b/commands/whereami.c
> > new file mode 100644
> > index 0000000000..3edb070fe8
> > --- /dev/null
> > +++ b/commands/whereami.c
> > @@ -0,0 +1,45 @@
> > +#include <common.h>
> > +#include <command.h>
> > +#include <complete.h>
> > +
> > +static volatile int data = 1;
> > +static volatile int bss;
> > +
> > +static void* code();
> > +static noinline void* code()
> > +{
> > +	void *ret;
> > +	__asm__ __volatile__(
> > +		".set	push\n"
> > +		".set	noreorder\n"
> > +		".set	noat\n"
> > +		"	move	$1, $31\n"
> > +		"	bal	255f\n"
> > +		"	nop\n"
> > +		"255:	move	%0, $31\n"
> > +		"	move	$31, $1\n"
> > +		".set	pop\n"
> > +		:"=r" (ret)
> > +	);
> > +	return ret;
> > +}
> > +
> > +static int do_whereami(int argc, char *argv[])
> > +{
> > +	volatile int stack;
> > +	int *heapp = malloc(sizeof(int));
> > +
> > +	printf("code   @ %p (%p)\n", code(), &code);
> > +	printf("data   @ %p\n", &data);
> > +	printf("bss    @ %p\n", &bss);
> > +	printf("heap   @ %p\n", heapp);
> > +	printf("stack  @ %p\n", &stack);
> > +	return 0;
> > +}
> > +
> > +BAREBOX_CMD_START(whereami)
> > +	.cmd		= do_whereami,
> > +	BAREBOX_CMD_DESC("print addresses from code, stack, heap and data sections")
> > +	BAREBOX_CMD_GROUP(CMD_GRP_INFO)
> > +	BAREBOX_CMD_COMPLETE(empty_complete)
> > +BAREBOX_CMD_END
> > 
> 
> Kind regards,
> Oleksij Rempel
> 
> -- 
> Pengutronix e.K.                           |                             |
> Industrial Linux Solutions                 | http://www.pengutronix.de/  |
> Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox