Re: [PATCH v3] gdb: bfin: new port

Mike Frysinger
2010-12-15T18:16:25Z

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On Wednesday, December 15, 2010 12:07:11 Mike Frysinger wrote:
> On Wednesday, December 15, 2010 11:49:32 Pedro Alves wrote:
> > Thanks for the explanations. This makes it so that the ASTAT.CC bit
> > can easily end up out of sync with the CC register in gdb's
> > regcache then, right? E.g., "p $cc = 1; p $asat" will still show the
> > $asat.cc as 0, IIUC. Does the kernel actually store CC on its
> > own slot in the register stack? I ask because I see it commented out
> > in bfin_regmap in gdbserver. If $cc was a pseudo-register _managed_ by
> > gdb (computed from ASAT), then this out-of-sync-ness would never happen.
>
> no, linux does not give CC dedicated space in the signal context. it does
> look like setting $cc on the command line results in out-of-sync values
> with $astat. i'll take a look at the pseudo helpers you referenced and
> see if i cant figure out how they work.

what do you think of this ? seems to work for me:
(gdb) set $cc = 0
(gdb) printf "%x %x\n", $astat, $cc
2002002 0
(gdb) set $cc = 1
(gdb) printf "%x %x\n", $astat, $cc
2002022 1
(gdb) set $astat = 0
(gdb) printf "%x %x\n", $astat, $cc
0 0
(gdb) set $astat = 0x20
(gdb) printf "%x %x\n", $astat, $cc
20 1
-mike

--- a/gdb/bfin-linux-tdep.c
+++ b/gdb/bfin-linux-tdep.c
@@ -88,7 +88,6 @@ static const int bfin_linux_sigcontext_reg_offset[BFIN_NUM_REGS] =
-1, /* %retn */
-1, /* %rete */
21 * 4, /* %pc */
- -1, /* %cc */
};

/* Signal trampolines. */
--- a/gdb/bfin-tdep.c
+++ b/gdb/bfin-tdep.c
@@ -116,16 +116,12 @@
/* The maximum bytes we search to skip the prologue. */
#define UPPER_LIMIT 40

-#define RETS_OFFSET 4
+/* ASTAT bits */
+#define ASTAT_CC_POS 5
+#define ASTAT_CC (1 << ASTAT_CC_POS)

/* Initial value: Register names used in BFIN's ISA documentation. */

@@ -683,6 +683,36 @@ bfin_register_name (struct gdbarch *gdbarch, int i)
return bfin_register_name_strings[i];
}

+static void
+bfin_pseudo_register_read (struct gdbarch *gdbarch, struct regcache *regcache,
+ int regnum, gdb_byte *buffer)
+{
+ gdb_byte *buf = (gdb_byte *) alloca (MAX_REGISTER_SIZE);
+
+ if (regnum != BFIN_CC_REGNUM)
+ internal_error (__FILE__, __LINE__,
+ _("invalid register number %d"), regnum);
+
+ regcache_raw_read (regcache, BFIN_ASTAT_REGNUM, buf);
+ buffer[1] = buffer[2] = buffer[3] = 0;
+ buffer[0] = !!(buf[0] & ASTAT_CC);
+}
+
+static void
+bfin_pseudo_register_write (struct gdbarch *gdbarch, struct regcache *regcache,
+ int regnum, const gdb_byte *buffer)
+{
+ gdb_byte *buf = (gdb_byte *) alloca (MAX_REGISTER_SIZE);
+
+ if (regnum != BFIN_CC_REGNUM)
+ internal_error (__FILE__, __LINE__,
+ _("invalid register number %d"), regnum);
+
+ regcache_raw_read (regcache, BFIN_ASTAT_REGNUM, buf);
+ buf[0] = (buf[0] & ~ASTAT_CC) | ((buffer[0] & 1) << ASTAT_CC_POS);
+ regcache_raw_write (regcache, BFIN_ASTAT_REGNUM, buf);
+}
+
static CORE_ADDR
bfin_frame_base_address (struct frame_info *this_frame, void **this_cache)
{
@@ -783,7 +813,9 @@ bfin_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
tdep->bfin_abi = abi;

set_gdbarch_num_regs (gdbarch, BFIN_NUM_REGS);
- set_gdbarch_num_pseudo_regs (gdbarch, 0);
+ set_gdbarch_pseudo_register_read (gdbarch, bfin_pseudo_register_read);
+ set_gdbarch_pseudo_register_write (gdbarch, bfin_pseudo_register_write);
+ set_gdbarch_num_pseudo_regs (gdbarch, BFIN_NUM_PSEUDO_REGS);
set_gdbarch_sp_regnum (gdbarch, BFIN_SP_REGNUM);
set_gdbarch_pc_regnum (gdbarch, BFIN_PC_REGNUM);
set_gdbarch_ps_regnum (gdbarch, BFIN_ASTAT_REGNUM);
--- a/gdb/bfin-tdep.h
+++ b/gdb/bfin-tdep.h
@@ -74,13 +74,14 @@ enum gdb_regnum {
BFIN_RETN_REGNUM,
BFIN_RETE_REGNUM,

- /* Pseudo Registers */
+ /* Pseudo Registers managed remotely. */
BFIN_PC_REGNUM,
- BFIN_CC_REGNUM,

- /* LAST ENTRY SHOULD NOT BE CHANGED. */
- BFIN_NUM_REGS /* The number of all registers. */
+ /* Pseudo Registers managed locally. */
+ BFIN_CC_REGNUM
};
+#define BFIN_NUM_REGS (BFIN_PC_REGNUM + 1)
+#define BFIN_NUM_PSEUDO_REGS (1)

/* The ABIs for Blackfin. */
enum bfin_abi

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