[DTrace-devel] [PATCH 6/6 v3] Add disassembler annotations for assoc arrays

[Eugene Loh]

Reviewed-by: Eugene Loh <eugene.loh at oracle.com>

On 3/10/22 12:55 AM, Kris Van Hees via DTrace-devel wrote:
> Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
> ---
>   libdtrace/dt_dis.c                         | 29 ++++++++++++++++++++++
>   test/unittest/disasm/tst.ann-gvar-assoc.r  |  2 ++
>   test/unittest/disasm/tst.ann-gvar-assoc.sh | 22 ++++++++++++++++
>   test/unittest/disasm/tst.ann-tvar-assoc.r  |  2 ++
>   test/unittest/disasm/tst.ann-tvar-assoc.sh | 22 ++++++++++++++++
>   5 files changed, 77 insertions(+)
>   create mode 100644 test/unittest/disasm/tst.ann-gvar-assoc.r
>   create mode 100755 test/unittest/disasm/tst.ann-gvar-assoc.sh
>   create mode 100644 test/unittest/disasm/tst.ann-tvar-assoc.r
>   create mode 100755 test/unittest/disasm/tst.ann-tvar-assoc.sh
>
> diff --git a/libdtrace/dt_dis.c b/libdtrace/dt_dis.c
> index d911dbf5..93e83296 100644
> --- a/libdtrace/dt_dis.c
> +++ b/libdtrace/dt_dis.c
> @@ -337,6 +337,35 @@ dt_dis_bpf_args(const dtrace_difo_t *dp, const char *fn,
>   			 dt_dis_varname_id(dp, in->imm + DIF_VAR_OTHER_UBASE,
>   					DIFV_SCOPE_THREAD, addr));
>   		return buf;
> +	} else if (strcmp(fn, "dt_get_assoc") == 0) {
> +		uint_t		varid;
> +
> +		/*
> +		 * We know that the previous four instructions exist and
> +		 * move the variable id to a register in the first instruction
> +		 * of that seqeuence (because we wrote the code generator to
> +		 * emit the instructions in this exact order.)
> +		 */
> +		in -= 4;
> +		varid = in->imm + DIF_VAR_OTHER_UBASE;
> +
> +		/*
> +		 * Four instructions prior to this there will be a STORE (TLS
> +		 * associative array) or a STORE_IMM (global associative array).
> +		 */
> +		in -= 4;
> +		if (in->code == (BPF_STX | BPF_MEM | BPF_DW))
> +			snprintf(buf, len, "self->%s[]",
> +				 dt_dis_varname_id(dp, varid, DIFV_SCOPE_THREAD,
> +						   addr));
> +		else if (in->code == (BPF_ST | BPF_MEM | BPF_DW))
> +			snprintf(buf, len, "%s[]",
> +				 dt_dis_varname_id(dp, varid, DIFV_SCOPE_GLOBAL,
> +						   addr));
> +		else
> +			snprintf(buf, len, "???[]");
> +
> +		return buf;
>   	}
>   
>   	return NULL;
> diff --git a/test/unittest/disasm/tst.ann-gvar-assoc.r b/test/unittest/disasm/tst.ann-gvar-assoc.r
> new file mode 100644
> index 00000000..f7563a51
> --- /dev/null
> +++ b/test/unittest/disasm/tst.ann-gvar-assoc.r
> @@ -0,0 +1,2 @@
> +85 0 1 0000 ffffffff    call dt_get_assoc             ! st[]
> +85 0 1 0000 ffffffff    call dt_get_assoc             ! ld[]
> diff --git a/test/unittest/disasm/tst.ann-gvar-assoc.sh b/test/unittest/disasm/tst.ann-gvar-assoc.sh
> new file mode 100755
> index 00000000..6690967d
> --- /dev/null
> +++ b/test/unittest/disasm/tst.ann-gvar-assoc.sh
> @@ -0,0 +1,22 @@
> +#!/bin/bash
> +#
> +# Oracle Linux DTrace.
> +# Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
> +# Licensed under the Universal Permissive License v 1.0 as shown at
> +# http://oss.oracle.com/licenses/upl.
> +#
> +
> +dtrace=$1
> +
> +$dtrace $dt_flags -Sen '
> +int st[int], ld[int];
> +
> +BEGIN
> +{
> +	st[2] = 42;
> +	trace(ld[5]);
> +	exit(0);
> +}
> +' 2>&1 | awk '/ call dt_get_assoc/ { sub(/^[^:]+: /, ""); print; }'
> +
> +exit $?
> diff --git a/test/unittest/disasm/tst.ann-tvar-assoc.r b/test/unittest/disasm/tst.ann-tvar-assoc.r
> new file mode 100644
> index 00000000..573c93e2
> --- /dev/null
> +++ b/test/unittest/disasm/tst.ann-tvar-assoc.r
> @@ -0,0 +1,2 @@
> +85 0 1 0000 ffffffff    call dt_get_assoc             ! self->st[]
> +85 0 1 0000 ffffffff    call dt_get_assoc             ! self->ld[]
> diff --git a/test/unittest/disasm/tst.ann-tvar-assoc.sh b/test/unittest/disasm/tst.ann-tvar-assoc.sh
> new file mode 100755
> index 00000000..354d8fbe
> --- /dev/null
> +++ b/test/unittest/disasm/tst.ann-tvar-assoc.sh
> @@ -0,0 +1,22 @@
> +#!/bin/bash
> +#
> +# Oracle Linux DTrace.
> +# Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
> +# Licensed under the Universal Permissive License v 1.0 as shown at
> +# http://oss.oracle.com/licenses/upl.
> +#
> +
> +dtrace=$1
> +
> +$dtrace $dt_flags -Sen '
> +self int st[int], ld[int];
> +
> +BEGIN
> +{
> +	self->st[2] = 42;
> +	trace(self->ld[5]);
> +	exit(0);
> +}
> +' 2>&1 | awk '/ call dt_get_assoc/ { sub(/^[^:]+: /, ""); print; }'
> +
> +exit $?