[PATCH] dwarf5: Fix parsing DWARF-5 line number tables

[PATCH] dwarf5: Fix parsing DWARF-5 line number tables

[H.J. Lu]

Advance rngs_ptr when parsing DW_RLE_offset_pair, which was missing in

commit c3757b583d2448a5996e83e374fb96ac7938da35
Author: Mark Wielaard <mark@klomp.org>
Date:   Tue Aug 25 15:33:00 2020 +0100

    Fix the linker's handling of DWARF-5 line number tables.

OK for master and 2.36 branch?

H.J.
---
	PR binutils/27231
	* dwarf2.c (read_rnglists): Advance rngs_ptr after
	_bfd_safe_read_leb128 when parsing DW_RLE_offset_pair.
---
 bfd/dwarf2.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/bfd/dwarf2.c b/bfd/dwarf2.c
index d1770ae4fdb..292d60c33d4 100644
--- a/bfd/dwarf2.c
+++ b/bfd/dwarf2.c
@@ -3265,9 +3265,11 @@ read_rnglists (struct comp_unit *unit, struct arange *arange,
 	  low_pc = base_address;
 	  low_pc += _bfd_safe_read_leb128 (abfd, rngs_ptr, &bytes_read,
 					   FALSE, rngs_end);
+	  rngs_ptr += bytes_read;
 	  high_pc = base_address;
 	  high_pc += _bfd_safe_read_leb128 (abfd, rngs_ptr, &bytes_read,
 					    FALSE, rngs_end);
+	  rngs_ptr += bytes_read;
 	  break;
 
 	case DW_RLE_start_end:
-- 
2.29.2

[PATCH] dwarf5: Fix parsing DWARF-5 line number tables

[H.J. Lu]

Advance rngs_ptr when parsing DW_RLE_offset_pair, which was missing in

commit c3757b583d2448a5996e83e374fb96ac7938da35
Author: Mark Wielaard <mark@klomp.org>
Date:   Tue Aug 25 15:33:00 2020 +0100

    Fix the linker's handling of DWARF-5 line number tables.

	PR binutils/27231
	* dwarf2.c (read_rnglists): Advance rngs_ptr after
	_bfd_safe_read_leb128 when parsing DW_RLE_offset_pair.
---
 bfd/dwarf2.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/bfd/dwarf2.c b/bfd/dwarf2.c
index d1770ae4fdb..292d60c33d4 100644
--- a/bfd/dwarf2.c
+++ b/bfd/dwarf2.c
@@ -3265,9 +3265,11 @@ read_rnglists (struct comp_unit *unit, struct arange *arange,
 	  low_pc = base_address;
 	  low_pc += _bfd_safe_read_leb128 (abfd, rngs_ptr, &bytes_read,
 					   FALSE, rngs_end);
+	  rngs_ptr += bytes_read;
 	  high_pc = base_address;
 	  high_pc += _bfd_safe_read_leb128 (abfd, rngs_ptr, &bytes_read,
 					    FALSE, rngs_end);
+	  rngs_ptr += bytes_read;
 	  break;
 
 	case DW_RLE_start_end:
-- 
2.29.2

Re: [PATCH] dwarf5: Fix parsing DWARF-5 line number tables

[Mark Wielaard]

Hi,

On Sat, Jan 23, 2021 at 03:29:34PM -0800, H.J. Lu wrote:
> Advance rngs_ptr when parsing DW_RLE_offset_pair, which was missing in
> 
> commit c3757b583d2448a5996e83e374fb96ac7938da35
> Author: Mark Wielaard <mark@klomp.org>
> Date:   Tue Aug 25 15:33:00 2020 +0100
> 
>     Fix the linker's handling of DWARF-5 line number tables.
> 
> OK for master and 2.36 branch?

I cannot approve binutils patches, but it looks ok to me.  No idea how
I missed this because the code does it correct for the other cases.

BTW. It would be nice to also get this on the binutils-2_35-branch an
do a 2.35.2 release for those distros that won't immediately upgrade
to binutils 2.36, but have already upgraded to gcc11 (like Fedora).

Thanks,

Mark

Re: [PATCH] dwarf5: Fix parsing DWARF-5 line number tables

[Alan Modra]

On Sat, Jan 23, 2021 at 03:29:35PM -0800, H.J. Lu wrote:
> Advance rngs_ptr when parsing DW_RLE_offset_pair, which was missing in
> 
> commit c3757b583d2448a5996e83e374fb96ac7938da35
> Author: Mark Wielaard <mark@klomp.org>
> Date:   Tue Aug 25 15:33:00 2020 +0100
> 
>     Fix the linker's handling of DWARF-5 line number tables.
> 
> 	PR binutils/27231
> 	* dwarf2.c (read_rnglists): Advance rngs_ptr after
> 	_bfd_safe_read_leb128 when parsing DW_RLE_offset_pair.

OK everywhere.

-- 
Alan Modra
Australia Development Lab, IBM

[PATCH] DWARF-5: Skip empty range in DWARF-5 line number tables

[H.J. Lu]

On Sat, Jan 23, 2021 at 5:34 PM Alan Modra <amodra@gmail.com> wrote:
>
> On Sat, Jan 23, 2021 at 03:29:35PM -0800, H.J. Lu wrote:
> > Advance rngs_ptr when parsing DW_RLE_offset_pair, which was missing in
> >
> > commit c3757b583d2448a5996e83e374fb96ac7938da35
> > Author: Mark Wielaard <mark@klomp.org>
> > Date:   Tue Aug 25 15:33:00 2020 +0100
> >
> >     Fix the linker's handling of DWARF-5 line number tables.
> >
> >       PR binutils/27231
> >       * dwarf2.c (read_rnglists): Advance rngs_ptr after
> >       _bfd_safe_read_leb128 when parsing DW_RLE_offset_pair.
>
> OK everywhere.
>

This patch is also needed to skip empty ranges in DWARF-5 line
number tables generated by GCC 11.

OK for master?

-- 
H.J.

[PATCH] DWARF-5: Skip empty range in DWARF-5 line number tables

[H.J. Lu]

[-- Attachment #1: Type: text/plain, Size: 897 bytes --]

On Sat, Jan 23, 2021 at 8:16 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Sat, Jan 23, 2021 at 5:34 PM Alan Modra <amodra@gmail.com> wrote:
> >
> > On Sat, Jan 23, 2021 at 03:29:35PM -0800, H.J. Lu wrote:
> > > Advance rngs_ptr when parsing DW_RLE_offset_pair, which was missing in
> > >
> > > commit c3757b583d2448a5996e83e374fb96ac7938da35
> > > Author: Mark Wielaard <mark@klomp.org>
> > > Date:   Tue Aug 25 15:33:00 2020 +0100
> > >
> > >     Fix the linker's handling of DWARF-5 line number tables.
> > >
> > >       PR binutils/27231
> > >       * dwarf2.c (read_rnglists): Advance rngs_ptr after
> > >       _bfd_safe_read_leb128 when parsing DW_RLE_offset_pair.
> >
> > OK everywhere.
> >
>
> This patch is also needed to skip empty ranges in DWARF-5 line
> number tables generated by GCC 11.
>
> OK for master?

Here is the real patch.  OK for master and 2.36/2.35 branches?

-- 
H.J.

[-- Attachment #2: 0001-DWARF-5-Skip-empty-range-in-DWARF-5-line-number-tabl.patch --]
[-- Type: text/x-patch, Size: 1957 bytes --]

From 543a13baa20bf3b567d4c9310524b386b5e850dd Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Sat, 23 Jan 2021 20:09:38 -0800
Subject: [PATCH] DWARF-5: Skip empty range in DWARF-5 line number tables

There is nothing special about 0 low or high pc or low_pc == high_pc in
.debug_rnglists.  The list termination is DW_RLE_end_of_list.  GCC 11
can generate the following entry in DWARF-5 line number tables:

.LLRL174:
        .byte   0x5
        .quad   .LBB2159
        .byte   0x4
        .uleb128 .LBB2159-.LBB2159
        .uleb128 .LBE2159-.LBB2159
        .byte   0x4
        .uleb128 .LBB2163-.LBB2159
        .uleb128 .LBE2163-.LBB2159
        .byte   0x4
        .uleb128 .LBB2174-.LBB2159
        .uleb128 .LBE2174-.LBB2159
        .byte   0

for

.LBB2163:
.LBB2161:
        .loc 1 7563 17 is_stmt 1 view .LVU1621
        .loc 1 7573 3 view .LVU1622
        .loc 1 7573 3 is_stmt 0 view .LVU1623
.LBE2161:
.LBE2163:
        .loc 1 7787 3 is_stmt 1 view .LVU1624
.LBB2164:
        .loc 1 7789 5 view .LVU1625
        .loc 1 7790 5 view .LVU1626
        .loc 1 7790 21 is_stmt 0 view .LVU1627
        movq    -312(%rbp), %rax
        movq    -336(%rbp), %r15
.LBB2165:

.LBB2163 and .LBE2163 have the same address.  Skip such empty range when
parsing DWARF-5 line number tables.

	PR binutils/27231
	* dwarf2.c (read_rnglists): Skip empty range when parsing line
	number tables.
---
 bfd/dwarf2.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/bfd/dwarf2.c b/bfd/dwarf2.c
index 292d60c33d4..22254abcd59 100644
--- a/bfd/dwarf2.c
+++ b/bfd/dwarf2.c
@@ -3289,8 +3289,9 @@ read_rnglists (struct comp_unit *unit, struct arange *arange,
 	  return FALSE;
 	}
 
-      if ((low_pc == 0 && high_pc == 0) || low_pc == high_pc)
-	return FALSE;
+      /* NB: Skip the empty range.  */
+      if (low_pc == high_pc)
+	continue;
 
       if (!arange_add (unit, arange, low_pc, high_pc))
 	return FALSE;
-- 
2.29.2

[PATCH] DWARF-5: Ignore empty range in DWARF-5 line number tables

[H.J. Lu]

[-- Attachment #1: Type: text/plain, Size: 1058 bytes --]

On Sun, Jan 24, 2021 at 3:58 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Sat, Jan 23, 2021 at 8:16 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > On Sat, Jan 23, 2021 at 5:34 PM Alan Modra <amodra@gmail.com> wrote:
> > >
> > > On Sat, Jan 23, 2021 at 03:29:35PM -0800, H.J. Lu wrote:
> > > > Advance rngs_ptr when parsing DW_RLE_offset_pair, which was missing in
> > > >
> > > > commit c3757b583d2448a5996e83e374fb96ac7938da35
> > > > Author: Mark Wielaard <mark@klomp.org>
> > > > Date:   Tue Aug 25 15:33:00 2020 +0100
> > > >
> > > >     Fix the linker's handling of DWARF-5 line number tables.
> > > >
> > > >       PR binutils/27231
> > > >       * dwarf2.c (read_rnglists): Advance rngs_ptr after
> > > >       _bfd_safe_read_leb128 when parsing DW_RLE_offset_pair.
> > >
> > > OK everywhere.
> > >
> >
> > This patch is also needed to skip empty ranges in DWARF-5 line
> > number tables generated by GCC 11.
> >
> > OK for master?
>
> Here is the real patch.  OK for master and 2.36/2.35 branches?
>

Here is the patch I am checking in.

-- 
H.J.

[-- Attachment #2: 0001-DWARF-5-Ignore-empty-range-in-DWARF-5-line-number-ta.patch --]
[-- Type: text/x-patch, Size: 1093 bytes --]

From b9c5c7f2a7b82dae504c0ffc9a00d82162ec4ba2 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Sat, 23 Jan 2021 20:09:38 -0800
Subject: [PATCH] DWARF-5: Ignore empty range in DWARF-5 line number tables

The DWARF5 spec does indeed explicitly say: "A bounded range entry whose
beginning and ending address offsets are equal (including zero) indicates
an empty range and may be ignored."

Since arange_add already ignores empty ranges, remove the whole check
should be equivalent to the check plus explicit continue.

	PR binutils/27231
	* dwarf2.c (read_rnglists): Ignore empty range when parsing line
	number tables.
---
 bfd/dwarf2.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/bfd/dwarf2.c b/bfd/dwarf2.c
index 292d60c33d4..240138d5982 100644
--- a/bfd/dwarf2.c
+++ b/bfd/dwarf2.c
@@ -3289,9 +3289,6 @@ read_rnglists (struct comp_unit *unit, struct arange *arange,
 	  return FALSE;
 	}
 
-      if ((low_pc == 0 && high_pc == 0) || low_pc == high_pc)
-	return FALSE;
-
       if (!arange_add (unit, arange, low_pc, high_pc))
 	return FALSE;
     }
-- 
2.29.2