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gdb/riscv: use a single regset supply function for riscv fbsd & linux

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The RISC-V x0 register is hard-coded to zero.  As such neither Linux
or FreeBSD supply the value of the register x0 in their core dump
files.

For FreeBSD we take care of this by manually supplying the value of x0
in riscv_fbsd_supply_gregset, however we don't do this for Linux.  As
a result after loading a core file on Linux we see this behaviour:

  (gdb) p $x0
  $1 = <unavailable>

In this commit I make riscv_fbsd_supply_gregset a common function that
can be shared between RISC-V for FreeBSD and Linux, this resolves the
above issue.

There is a similar problem for the two registers `fflags` and `frm`.
These two floating point related CSRs are a little weird.  They are
separate CSRs in the RISC-V specification, but are actually sub-fields
of the `fcsr` CSR.

As a result neither Linux or FreeBSD supply the `fflags` or `frm`
registers as separate fields in their core dumps, and so, after
restoring a core dump these register are similarly unavailable.

In this commit I supply `fflags` and `frm` by first asking for the
value of `fcsr`, extracting the two fields, and using these to supply
the values for `fflags` and `frm`.

gdb/ChangeLog:

	* riscv-fbsd-tdep.c (riscv_fbsd_supply_gregset): Delete.
	(riscv_fbsd_gregset): Use riscv_supply_regset.
	(riscv_fbsd_fpregset): Likewise.
	* riscv-linux-tdep.c (riscv_linux_gregset): Likewise.
	(riscv_linux_fregset): Likewise.
	* riscv-tdep.c (riscv_supply_regset): Define new function.
	* riscv-tdep.h (riscv_supply_regset): Declare new function.
This commit is contained in:
Andrew Burgess
2020-12-02 15:10:06 +00:00
parent 326adec374
commit 6a9ad81c44
5 changed files with 87 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

50
gdb/riscv-tdep.c
View File

@ -3786,6 +3786,56 @@ riscv_init_reggroups ()
csr_reggroup = reggroup_new ("csr", USER_REGGROUP);
}
/* See riscv-tdep.h. */
void
riscv_supply_regset (const struct regset *regset,
struct regcache *regcache, int regnum,
const void *regs, size_t len)
{
regcache->supply_regset (regset, regnum, regs, len);
if (regnum == -1 || regnum == RISCV_ZERO_REGNUM)
regcache->raw_supply_zeroed (RISCV_ZERO_REGNUM);
if (regnum == -1 || regnum == RISCV_CSR_FFLAGS_REGNUM
|| regnum == RISCV_CSR_FRM_REGNUM)
{
int fcsr_regnum = RISCV_CSR_FCSR_REGNUM;
/* Ensure that FCSR has been read into REGCACHE. */
if (regnum != -1)
regcache->supply_regset (regset, fcsr_regnum, regs, len);
/* Grab the FCSR value if it is now in the regcache. We must check
the status first as, if the register was not supplied by REGSET,
this call will trigger a recursive attempt to fetch the
registers. */
if (regcache->get_register_status (fcsr_regnum) == REG_VALID)
{
ULONGEST fcsr_val;
regcache->raw_read (fcsr_regnum, &fcsr_val);
/* Extract the fflags and frm values. */
ULONGEST fflags_val = fcsr_val & 0x1f;
ULONGEST frm_val = (fcsr_val >> 5) & 0x7;
/* And supply these if needed. */
if (regnum == -1 || regnum == RISCV_CSR_FFLAGS_REGNUM)
regcache->raw_supply_integer (RISCV_CSR_FFLAGS_REGNUM,
(gdb_byte *) &fflags_val,
sizeof (fflags_val),
/* is_signed */ false);
if (regnum == -1 || regnum == RISCV_CSR_FRM_REGNUM)
regcache->raw_supply_integer (RISCV_CSR_FRM_REGNUM,
(gdb_byte *)&frm_val,
sizeof (fflags_val),
/* is_signed */ false);
}
}
}
void _initialize_riscv_tdep ();
void
_initialize_riscv_tdep ()