[PATCH] Fix arm-netbsd build error
Kamil Rytarowski
n54@gmx.com
Wed Feb 12 17:10:00 GMT 2020
On 12.02.2020 17:28, Christian Biesinger wrote:
> On Wed, Feb 12, 2020 at 7:29 AM Alan Hayward <Alan.Hayward@arm.com> wrote:
>>
>>
>>
>>> On 11 Feb 2020, at 23:34, Christian Biesinger via gdb-patches <gdb-patches@sourceware.org> wrote:
>>>
>>> On Tue, Feb 11, 2020 at 4:55 PM Christian Biesinger
>>> <cbiesinger@google.com> wrote:
>>>>
>>>> The floating point register interface has changed to this:
>>>> https://github.com/NetBSD/src/blob/trunk/sys/arch/arm/include/reg.h
>>>>
>>>> It now uses VFP instead of FPA registers. This patch updates
>>>> arm-nbsd-nat.c accordingly.
>>>>
>>>> Tested by compiling on arm-netbsd on qemu. For actually testing, there
>>>> seems to be something missing as "info registers" only shows FPA
>>>> registers and no VFP ones. I am still investigating why this is;
>>>> please let me know if you know. However, I think this is still good
>>>> to check in as-is.
>>>
>>> Hm... this is perhaps because arm_netbsd_nat_target does not implement
>>> read_description; if it returned arm_read_description
>>> (ARM_FP_TYPE_VFPV2) this may work?
>>>
>>
>> Yes, looks like netbsd isn’t using any target description functionality.
>>
>> I suspect the code is getting into arm_gdbarch_init() with a null tdesc,
>> and then using the AUTO setting. But that’s just a guess.
>>
>> Implementing read_description as you suggest should help. However,
>> read_description should probably do HWCAP checking similar to the
>> arm_linux_nat_target and arm_fbsd_nat_target versions.
>>
>> Without that, I’d worry that your patch below might start writing off the
>> end of the regcache that had been allocated for a fewer number of registers.
>
> Hm... well, I've probably spent entirely too much time on this
> already, but just in case there's an easy fix -- Kamil, does NetBSD
> provide an API similar to Linux's HWCAP API that would let me check
> which VFP version the current CPU is using? It seems AUXV does not
> contain HWCAP data on NetBSD, unlike Linux/FreeBSD, though I may be
> missing something.
>
> (Compare arm_fbsd_read_description_auxv /
> arm_linux_nat_target::read_description)
>
> Christian
>
Thank you for your work.
HWCAP in auxv is not supported (although there is a stub for it).
Here is a complete algorithm to detect FPU on ARM 32-bit.
http://netbsd.org/~kamil/arm-fpu.c
>>
>>>>
>>>> gdb/ChangeLog:
>>>>
>>>> 2020-02-11 Christian Biesinger <cbiesinger@google.com>
>>>>
>>>> * arm-nbsd-nat.c (arm_supply_fparegset): Rename to...
>>>> (arm_supply_vfpregset): ...this, and update to use VFP registers.
>>>> (fetch_fp_register): Update.
>>>> (fetch_fp_regs): Update.
>>>> (store_fp_register): Update.
>>>> (store_fp_regs): Update.
>>>> (fetch_elfcore_registers): Update.
>>>> ---
>>>> gdb/arm-nbsd-nat.c | 80 ++++++++++++++++++++--------------------------
>>>> 1 file changed, 34 insertions(+), 46 deletions(-)
>>>>
>>>> diff --git a/gdb/arm-nbsd-nat.c b/gdb/arm-nbsd-nat.c
>>>> index 11afc289c3..8027f54dfe 100644
>>>> --- a/gdb/arm-nbsd-nat.c
>>>> +++ b/gdb/arm-nbsd-nat.c
>>>> @@ -65,15 +65,13 @@ arm_supply_gregset (struct regcache *regcache, struct reg *gregset)
>>>> }
>>>>
>>>> static void
>>>> -arm_supply_fparegset (struct regcache *regcache, struct fpreg *fparegset)
>>>> +arm_supply_vfpregset (struct regcache *regcache, struct fpreg *fpregset)
>>>> {
>>>> - int regno;
>>>> -
>>>> - for (regno = ARM_F0_REGNUM; regno <= ARM_F7_REGNUM; regno++)
>>>> - regcache->raw_supply (regno,
>>>> - (char *) &fparegset->fpr[regno - ARM_F0_REGNUM]);
>>>> + struct vfpreg &vfp = fpregset->fpr_vfp;
>>>> + for (int regno = ARM_D0_REGNUM; regno <= ARM_D31_REGNUM; regno++)
>>>> + regcache->raw_supply (regno, (char *) &vfp.vfp_regs[regno - ARM_D0_REGNUM]);
>>>>
>>>> - regcache->raw_supply (ARM_FPS_REGNUM, (char *) &fparegset->fpr_fpsr);
>>>> + regcache->raw_supply (ARM_FPSCR_REGNUM, (char *) &vfp.vfp_fpscr);
>>>> }
>>>>
>>>> static void
>>>> @@ -147,10 +145,10 @@ static void
>>>> fetch_fp_register (struct regcache *regcache, int regno)
>>>> {
>>>> struct fpreg inferior_fp_registers;
>>>> - int ret;
>>>> + int ret = ptrace (PT_GETFPREGS, regcache->ptid ().pid (),
>>>> + (PTRACE_TYPE_ARG3) &inferior_fp_registers, 0);
>>>>
>>>> - ret = ptrace (PT_GETFPREGS, regcache->ptid ().pid (),
>>>> - (PTRACE_TYPE_ARG3) &inferior_fp_registers, 0);
>>>> + struct vfpreg &vfp = inferior_fp_registers.fpr_vfp;
>>>>
>>>> if (ret < 0)
>>>> {
>>>> @@ -158,18 +156,15 @@ fetch_fp_register (struct regcache *regcache, int regno)
>>>> return;
>>>> }
>>>>
>>>> - switch (regno)
>>>> + if (regno == ARM_FPSCR_REGNUM)
>>>> + regcache->raw_supply (ARM_FPSCR_REGNUM, (char *) &vfp.vfp_fpscr);
>>>> + else if (regno >= ARM_D0_REGNUM && regno <= ARM_D31_REGNUM)
>>>> {
>>>> - case ARM_FPS_REGNUM:
>>>> - regcache->raw_supply (ARM_FPS_REGNUM,
>>>> - (char *) &inferior_fp_registers.fpr_fpsr);
>>>> - break;
>>>> -
>>>> - default:
>>>> - regcache->raw_supply
>>>> - (regno, (char *) &inferior_fp_registers.fpr[regno - ARM_F0_REGNUM]);
>>>> - break;
>>>> + regcache->raw_supply (regno,
>>>> + (char *) &vfp.vfp_regs[regno - ARM_D0_REGNUM]);
>>>> }
>>>> + else
>>>> + warning (_("Invalid register number."));
>>>> }
>>>>
>>>> static void
>>>> @@ -188,7 +183,7 @@ fetch_fp_regs (struct regcache *regcache)
>>>> return;
>>>> }
>>>>
>>>> - arm_supply_fparegset (regcache, &inferior_fp_registers);
>>>> + arm_supply_vfpregset (regcache, &inferior_fp_registers);
>>>> }
>>>>
>>>> void
>>>> @@ -327,10 +322,9 @@ static void
>>>> store_fp_register (const struct regcache *regcache, int regno)
>>>> {
>>>> struct fpreg inferior_fp_registers;
>>>> - int ret;
>>>> -
>>>> - ret = ptrace (PT_GETFPREGS, regcache->ptid ().pid (),
>>>> - (PTRACE_TYPE_ARG3) &inferior_fp_registers, 0);
>>>> + int ret = ptrace (PT_GETFPREGS, regcache->ptid ().pid (),
>>>> + (PTRACE_TYPE_ARG3) &inferior_fp_registers, 0);
>>>> + struct vfpreg &vfp = inferior_fp_registers.fpr_vfp;
>>>>
>>>> if (ret < 0)
>>>> {
>>>> @@ -338,18 +332,15 @@ store_fp_register (const struct regcache *regcache, int regno)
>>>> return;
>>>> }
>>>>
>>>> - switch (regno)
>>>> + if (regno == ARM_FPSCR_REGNUM)
>>>> + regcache->raw_collect (ARM_FPSCR_REGNUM, (char *) &vfp.vfp_fpscr);
>>>> + else if (regno >= ARM_D0_REGNUM && regno <= ARM_D31_REGNUM)
>>>> {
>>>> - case ARM_FPS_REGNUM:
>>>> - regcache->raw_collect (ARM_FPS_REGNUM,
>>>> - (char *) &inferior_fp_registers.fpr_fpsr);
>>>> - break;
>>>> -
>>>> - default:
>>>> - regcache->raw_collect
>>>> - (regno, (char *) &inferior_fp_registers.fpr[regno - ARM_F0_REGNUM]);
>>>> - break;
>>>> + regcache->raw_collect (regno,
>>>> + (char *) &vfp.vfp_regs[regno - ARM_D0_REGNUM]);
>>>> }
>>>> + else
>>>> + warning (_("Invalid register number."));
>>>>
>>>> ret = ptrace (PT_SETFPREGS, regcache->ptid ().pid (),
>>>> (PTRACE_TYPE_ARG3) &inferior_fp_registers, 0);
>>>> @@ -361,20 +352,17 @@ store_fp_register (const struct regcache *regcache, int regno)
>>>> static void
>>>> store_fp_regs (const struct regcache *regcache)
>>>> {
>>>> - struct fpreg inferior_fp_registers;
>>>> - int ret;
>>>> - int regno;
>>>> + struct fpreg fpregs;
>>>>
>>>> -
>>>> - for (regno = ARM_F0_REGNUM; regno <= ARM_F7_REGNUM; regno++)
>>>> + for (int regno = ARM_D0_REGNUM; regno <= ARM_D31_REGNUM; regno++)
>>>> regcache->raw_collect
>>>> - (regno, (char *) &inferior_fp_registers.fpr[regno - ARM_F0_REGNUM]);
>>>> + (regno, (char *) &fpregs.fpr_vfp.vfp_regs[regno - ARM_D0_REGNUM]);
>>>>
>>>> - regcache->raw_collect (ARM_FPS_REGNUM,
>>>> - (char *) &inferior_fp_registers.fpr_fpsr);
>>>> + regcache->raw_collect (ARM_FPSCR_REGNUM,
>>>> + (char *) &fpregs.fpr_vfp.vfp_fpscr);
>>>>
>>>> - ret = ptrace (PT_SETFPREGS, regcache->ptid ().pid (),
>>>> - (PTRACE_TYPE_ARG3) &inferior_fp_registers, 0);
>>>> + int ret = ptrace (PT_SETFPREGS, regcache->ptid ().pid (),
>>>> + (PTRACE_TYPE_ARG3) &fpregs, 0);
>>>>
>>>> if (ret < 0)
>>>> warning (_("unable to store floating-point registers"));
>>>> @@ -427,7 +415,7 @@ fetch_elfcore_registers (struct regcache *regcache,
>>>> /* The memcpy may be unnecessary, but we can't really be sure
>>>> of the alignment of the data in the core file. */
>>>> memcpy (&fparegset, core_reg_sect, sizeof (fparegset));
>>>> - arm_supply_fparegset (regcache, &fparegset);
>>>> + arm_supply_vfpregset (regcache, &fparegset);
>>>> }
>>>> break;
>>>>
>>>> --
>>>> 2.25.0.225.g125e21ebc7-goog
>>>>
>>
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