[DTrace-devel] [PATCH 2/2 v3] Show signed values for signed immediate conditional branches

[Kris Van Hees]

On Tue, Mar 29, 2022 at 12:44:44PM -0400, Eugene Loh via DTrace-devel wrote:
> On 3/29/22 12:41 AM, Kris Van Hees via DTrace-devel wrote:
> 
> > The disassembler will now print negative values correctly in signed
> > conditional branch instructions with an immediate operand.
> > 
> > Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
> > ---
> >   libdtrace/dt_dis.c                    | 29 +++++++++++++++++++--------
> >   test/unittest/disasm/tst.ann-js-neg.r |  2 ++
> I'm confused.  Is there a branch that already has a test?  Or was there
> supposed to be a test in this patch that was omitted?  (I'm guessing the
> latter.)

Go figure I mistyped the git add...  v4 on its way.

> >   2 files changed, 23 insertions(+), 8 deletions(-)
> >   create mode 100644 test/unittest/disasm/tst.ann-js-neg.r
> > 
> > diff --git a/libdtrace/dt_dis.c b/libdtrace/dt_dis.c
> > index bfd639c6..b5a1f067 100644
> > --- a/libdtrace/dt_dis.c
> > +++ b/libdtrace/dt_dis.c
> > @@ -286,6 +286,19 @@ dt_dis_branch_imm(const dtrace_difo_t *dp, const char *name, uint_t addr,
> >   	return 0;
> >   }
> > +/*ARGSUSED*/
> > +static uint_t
> > +dt_dis_sbranch_imm(const dtrace_difo_t *dp, const char *name, uint_t addr,
> > +	      const struct bpf_insn *in, const char *rname, FILE *fp)
> > +{
> > +	int	n;
> > +
> > +	n = fprintf(fp, "%-4s %s, %d, %d", name, reg(in->dst_reg), in->imm,
> > +		    in->off);
> > +	fprintf(fp, "%*s! -> %03u\n", DT_DIS_PAD(n), "", addr + 1 + in->off);
> > +	return 0;
> > +}
> > +
> >   /*ARGSUSED*/
> >   static uint_t
> >   dt_dis_load(const dtrace_difo_t *dp, const char *name, uint_t addr,
> > @@ -720,10 +733,10 @@ dt_dis_difo(const dtrace_difo_t *dp, FILE *fp, const dt_ident_t *idp,
> >   		INSN3(JMP32, JLT, K)	= { "jlt", dt_dis_branch_imm },
> >   		INSN3(JMP32, JGE, K)	= { "jge", dt_dis_branch_imm },
> >   		INSN3(JMP32, JLE, K)	= { "jle", dt_dis_branch_imm },
> > -		INSN3(JMP32, JSGT, K)	= { "jsgt", dt_dis_branch_imm },
> > -		INSN3(JMP32, JSLT, K)	= { "jslt", dt_dis_branch_imm },
> > -		INSN3(JMP32, JSGE, K)	= { "jsge", dt_dis_branch_imm },
> > -		INSN3(JMP32, JSLE, K)	= { "jsle", dt_dis_branch_imm },
> > +		INSN3(JMP32, JSGT, K)	= { "jsgt", dt_dis_sbranch_imm },
> > +		INSN3(JMP32, JSLT, K)	= { "jslt", dt_dis_sbranch_imm },
> > +		INSN3(JMP32, JSGE, K)	= { "jsge", dt_dis_sbranch_imm },
> > +		INSN3(JMP32, JSLE, K)	= { "jsle", dt_dis_sbranch_imm },
> >   		INSN3(JMP32, JSET, K)	= { "jset", dt_dis_branch_imm },
> >   		/* 64-bit jump ops, op(dst, src) */
> >   		INSN3(JMP, JEQ, X)	= { "jeq", dt_dis_branch },
> > @@ -744,10 +757,10 @@ dt_dis_difo(const dtrace_difo_t *dp, FILE *fp, const dt_ident_t *idp,
> >   		INSN3(JMP, JLT, K)	= { "jlt", dt_dis_branch_imm },
> >   		INSN3(JMP, JGE, K)	= { "jge", dt_dis_branch_imm },
> >   		INSN3(JMP, JLE, K)	= { "jle", dt_dis_branch_imm },
> > -		INSN3(JMP, JSGT, K)	= { "jsgt", dt_dis_branch_imm },
> > -		INSN3(JMP, JSLT, K)	= { "jslt", dt_dis_branch_imm },
> > -		INSN3(JMP, JSGE, K)	= { "jsge", dt_dis_branch_imm },
> > -		INSN3(JMP, JSLE, K)	= { "jsle", dt_dis_branch_imm },
> > +		INSN3(JMP, JSGT, K)	= { "jsgt", dt_dis_sbranch_imm },
> > +		INSN3(JMP, JSLT, K)	= { "jslt", dt_dis_sbranch_imm },
> > +		INSN3(JMP, JSGE, K)	= { "jsge", dt_dis_sbranch_imm },
> > +		INSN3(JMP, JSLE, K)	= { "jsle", dt_dis_sbranch_imm },
> >   		INSN3(JMP, JSET, K)	= { "jset", dt_dis_branch_imm },
> >   		INSN2(JMP, JA)		= { "ja", dt_dis_jump },
> >   		/* Store instructions, [dst + off] = src */
> > diff --git a/test/unittest/disasm/tst.ann-js-neg.r b/test/unittest/disasm/tst.ann-js-neg.r
> > new file mode 100644
> > index 00000000..d70a02ff
> > --- /dev/null
> > +++ b/test/unittest/disasm/tst.ann-js-neg.r
> > @@ -0,0 +1,2 @@
> > +75 0 0 XXXX 00000000    jsge %r0, 0, 3
> > +d5 0 0 XXXX fffff800    jsle %r0, -2048, 2
> 
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