Re: [PATCH] Fix call functions command bug in 64-bit programs for AIX

[Aditya Kamath1 <Aditya.Kamath1@ibm.com>]

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Hi Ulrich,

>Can you show the specific debug code you have added to get this
>output?

I have added the printf in the

store_register (struct regcache *regcache, int regno)

function.. This is where ptrace will put the contents in the register..

I have pasted it below..

Have a nice day ahead.

Thanks and regards,
Aditya.


else

        {

          /* PT_WRITE_GPR requires the buffer parameter to point to an 8-byte

             area, even if the register is really only 32 bits.  */

          long long buf;

          if (register_size (gdbarch, regno) == 8)

            memcpy (&buf, addr, 8);

          else

            buf = *addr;

          printf ("val in regno = %d via buf is %d and *addr is %d\n", regno, bu

f, *addr);

          rs6000_ptrace64 (PT_WRITE_GPR, pid, nr, 0, &buf);

        }

________________________________
From: Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
Sent: 14 November 2022 23:49
To: gdb-patches@sourceware.org <gdb-patches@sourceware.org>; Aditya Kamath1 <Aditya.Kamath1@ibm.com>; simon.marchi@efficios.com <simon.marchi@efficios.com>
Cc: Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>; Sanket Rathi <sanrathi@in.ibm.com>
Subject: Re: [PATCH] Fix call functions command bug in 64-bit programs for AIX

Aditya Kamath1 <Aditya.Kamath1@ibm.com> wrote:

>I have added a print statement for what we get in *addr via raw_supply
>and what we copy in long buf that will go in the ptrace. Also, I print
>the regno. As a fact register number R3 to R10 are reserved for
>function parameters.

Yes, of course just looking at "*addr" will be wrong in 64-bit mode,
but that doesn't matter since nobody is actually ever looking at
"*addr" in this case.

>(gdb) call num2print (2, 3, 4, 5)
>val in regno 3 via buf is 0 and *addr is 2
>val in regno 4 via buf is 0 and *addr is 1077936128
>val in regno 5 via buf is 0 and *addr is 4
>val in regno 6 via buf is 0 and *addr is 5
>val in regno 1 via buf is -1696 and *addr is 268435455
>val in regno 67 via buf is 1152 and *addr is 1

Can you show the specific debug code you have added to get this
output?

>(gdb) info reg
>r0             0x1000004f4         4294968564
>r1             0xffffffffffff9e0   1152921504606845408
>r2             0x1100002e0         4563403488
>r3             0x1                 1
>r4             0xffffffffffffad0   1152921504606845648
>r5             0xffffffffffffae0   1152921504606845664
>r6             0x800000000000d032  9223372036854829106
>r7             0xfffffffffffffe0   1152921504606846944
>r8             0x0                 0
>r9             0x1                 1
>r10            0x0                 0
>r11            0x1030              4144
>r12            0xf1000600005901d8  17365886760216232408
>r13            0xbadc0ffee0ddf00d  13464654573299691533

From what I can see these are the values after the
num2print routine has returned and the original
values were restored by GDB.

If you want to see the values *in num2print* you need
to set a breakpoint at num2print before calling it.


Bye,
Ulrich