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Re: [PATCH v3] Fix arm-netbsd build error: convert from FPA to VFP
- From: Alan Hayward <Alan dot Hayward at arm dot com>
- To: Christian Biesinger <cbiesinger at google dot com>
- Cc: gdb-patches <gdb-patches at sourceware dot org>, nd <nd at arm dot com>
- Date: Mon, 2 Mar 2020 11:42:26 +0000
- Subject: Re: [PATCH v3] Fix arm-netbsd build error: convert from FPA to VFP
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- References: <EC3E784C-DD98-4EE1-90F2-9FF09795E7C3@arm.com> <20200228191905.30413-1-cbiesinger@google.com>
> On 28 Feb 2020, at 19:19, Christian Biesinger via gdb-patches <gdb-patches@sourceware.org> wrote:
>
> Hi Alan,
>
> there is already a num_vfp_registers field in tdep, so I thought it easiest
> to just use that. Does that look good? See below.
>
That works for the ARM_FP_TYPE_NONE case.
I had to convince myself it works for the aarch32_read_description case.
And after thinking it through, I’m happy because both have the same size
FP register banks.
So, ok to push.
> Thanks,
> Christian
>
> ----
>
> 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.
>
> Also implements read_description so that these registers are correctly
> printed by "info registers" et al.
>
> Tested by compiling & running on arm-netbsd on qemu.
>
> 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.
> (arm_netbsd_nat_target::read_description): New function.
> (fetch_elfcore_registers): Update.
> ---
> gdb/arm-nbsd-nat.c | 121 +++++++++++++++++++++++++--------------------
> 1 file changed, 68 insertions(+), 53 deletions(-)
>
> diff --git a/gdb/arm-nbsd-nat.c b/gdb/arm-nbsd-nat.c
> index 11afc289c3..cee7917db2 100644
> --- a/gdb/arm-nbsd-nat.c
> +++ b/gdb/arm-nbsd-nat.c
> @@ -26,10 +26,12 @@
> #include "target.h"
> #include <sys/types.h>
> #include <sys/ptrace.h>
> +#include <sys/sysctl.h>
> #include <machine/reg.h>
> #include <machine/frame.h>
>
> #include "arm-tdep.h"
> +#include "aarch32-tdep.h"
> #include "inf-ptrace.h"
>
> class arm_netbsd_nat_target final : public inf_ptrace_target
> @@ -38,6 +40,7 @@ public:
> /* Add our register access methods. */
> void fetch_registers (struct regcache *, int) override;
> void store_registers (struct regcache *, int) override;
> + const struct target_desc *read_description () override;
> };
>
> static arm_netbsd_nat_target the_arm_netbsd_nat_target;
> @@ -65,15 +68,17 @@ 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;
> + struct gdbarch_tdep *tdep = gdbarch_tdep (regcache->arch ());
> + if (tdep->vfp_register_count == 0)
> + return;
>
> - 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 = 0; regno <= tdep->vfp_register_count; regno++)
> + regcache->raw_supply (regno + ARM_D0_REGNUM, (char *) &vfp.vfp_regs[regno]);
>
> - regcache->raw_supply (ARM_FPS_REGNUM, (char *) &fparegset->fpr_fpsr);
> + regcache->raw_supply (ARM_FPSCR_REGNUM, (char *) &vfp.vfp_fpscr);
> }
>
> static void
> @@ -147,10 +152,10 @@ 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 +163,17 @@ fetch_fp_register (struct regcache *regcache, int regno)
> return;
> }
>
> - switch (regno)
> + struct gdbarch_tdep *tdep = gdbarch_tdep (regcache->arch ());
> + if (regno == ARM_FPSCR_REGNUM)
> + regcache->raw_supply (ARM_FPSCR_REGNUM, (char *) &vfp.vfp_fpscr);
> + else if (regno >= ARM_D0_REGNUM
> + && regno <= ARM_D0_REGNUM + tdep->vfp_register_count)
> {
> - 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 +192,7 @@ fetch_fp_regs (struct regcache *regcache)
> return;
> }
>
> - arm_supply_fparegset (regcache, &inferior_fp_registers);
> + arm_supply_vfpregset (regcache, &inferior_fp_registers);
> }
>
> void
> @@ -327,10 +331,9 @@ 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 +341,17 @@ store_fp_register (const struct regcache *regcache, int regno)
> return;
> }
>
> - switch (regno)
> + struct gdbarch_tdep *tdep = gdbarch_tdep (regcache->arch ());
> + if (regno == ARM_FPSCR_REGNUM)
> + regcache->raw_collect (ARM_FPSCR_REGNUM, (char *) &vfp.vfp_fpscr);
> + else if (regno >= ARM_D0_REGNUM
> + && regno <= ARM_D0_REGNUM + tdep->vfp_register_count)
> {
> - 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 +363,20 @@ 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 gdbarch_tdep *tdep = gdbarch_tdep (regcache->arch ());
> + if (tdep->vfp_register_count == 0)
> + return;
>
> - for (regno = ARM_F0_REGNUM; regno <= ARM_F7_REGNUM; regno++)
> + struct fpreg fpregs;
> + for (int regno = 0; regno <= tdep->vfp_register_count; regno++)
> regcache->raw_collect
> - (regno, (char *) &inferior_fp_registers.fpr[regno - ARM_F0_REGNUM]);
> + (regno + ARM_D0_REGNUM, (char *) &fpregs.fpr_vfp.vfp_regs[regno]);
>
> - 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"));
> @@ -397,6 +399,23 @@ arm_netbsd_nat_target::store_registers (struct regcache *regcache, int regno)
> }
> }
>
> +const struct target_desc *
> +arm_netbsd_nat_target::read_description ()
> +{
> + int flag;
> + size_t len = sizeof (flag);
> +
> + if (sysctlbyname("machdep.fpu_present", &flag, &len, NULL, 0) != 0
> + || !flag)
> + return arm_read_description (ARM_FP_TYPE_NONE);
> +
> + len = sizeof(flag);
> + if (sysctlbyname("machdep.neon_present", &flag, &len, NULL, 0) == 0 && flag)
> + return aarch32_read_description ();
> +
> + return arm_read_description (ARM_FP_TYPE_VFPV3);
> +}
> +
> static void
> fetch_elfcore_registers (struct regcache *regcache,
> gdb_byte *core_reg_sect, unsigned core_reg_size,
> @@ -420,15 +439,11 @@ fetch_elfcore_registers (struct regcache *regcache,
> break;
>
> case 2:
> - if (core_reg_size != sizeof (struct fpreg))
> - warning (_("wrong size of FPA register set in core file"));
> - else
> - {
> - /* 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);
> - }
> + /* cbiesinger/2020-02-12 -- as far as I can tell, ARM/NetBSD does
> + not write any floating point registers into the core file (tested
> + with NetBSD 9.1_RC1). When it does, this block will need to read them,
> + and the arm-netbsd gdbarch will need a core_read_description function
> + to return the right description for them. */
> break;
>
> default:
> --
> 2.25.0.265.gbab2e86ba0-goog
>