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debugedit/SOURCES/0001-debugedit-Add-support-for-.debug_str_offsets-DW_FORM.patch

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From 3e7aeeab4f744ad15108775685db68d3a35b0735 Mon Sep 17 00:00:00 2001
From: Mark Wielaard <mark@klomp.org>
Date: Thu, 23 Mar 2023 18:07:40 +0100
Subject: [PATCH] debugedit: Add support for .debug_str_offsets (DW_FORM_strx)
In theory supporting strx .debug_str_offsets is easy, the strings in
.debug_str are just read through an indirection table. When the
strings are updated in .debug_str we just need to rewrite the
indirection table.
The tricky part is the ET_REL (object files or kernel modules)
support. Relocation reading is "global" per section and we expect to
read a relocation only once. But we need to read the
DW_AT_str_offsets_base before reading any strx form attributes. So we
read that first, then reset the relptr. And when we read from the
.debug_str_offsets section we need to save and restore the .debug_info
relptr.
* tools/debugedit.c (do_read_24): New function.
(str_offsets_base): New static variable.
(buf_read_ule24): New function.
(buf_read_ube24): Likewise.
(setup_relbuf): Handle .debug_str_offsets.
(do_read_uleb128): New function.
(do_read_str_form_relocated): Likewise.
(read_abbrev): Handle DW_FORM_strx[1234].
(edit_strp): Take the actual string form as argument.
Use do_read_str_form_relocated.
(read_dwarf5_line_entries): Pass form to edit_strp.
(edit_attributes_str_comp_dir): Take the actual string
form as argument. Use do_read_str_form_relocated.
(edit_attributes): Handle DW_FORM_strx[1234].
(edit_info): Read DW_AT_str_offsets_base first.
(update_str_offsets): New function.
(edit_dwarf2): Setup do_read_24. Call update_str_offsets.
https://sourceware.org/bugzilla/show_bug.cgi?id=28728
Signed-off-by: Mark Wielaard <mark@klomp.org>
---
tools/debugedit.c | 216 ++++++++++++++++++++++++++++++++++++++++------
1 file changed, 192 insertions(+), 24 deletions(-)
diff --git a/tools/debugedit.c b/tools/debugedit.c
index e654981..7802f9f 100644
--- a/tools/debugedit.c
+++ b/tools/debugedit.c
@@ -1,4 +1,5 @@
/* Copyright (C) 2001-2003, 2005, 2007, 2009-2011, 2016, 2017 Red Hat, Inc.
+ Copyright (C) 2022, 2023 Mark J. Wielaard <mark@klomp.org>
Written by Alexander Larsson <alexl@redhat.com>, 2002
Based on code by Jakub Jelinek <jakub@redhat.com>, 2001.
String/Line table rewriting by Mark Wielaard <mjw@redhat.com>, 2017.
@@ -264,6 +264,7 @@ typedef struct
})
static uint16_t (*do_read_16) (unsigned char *ptr);
+static uint32_t (*do_read_24) (unsigned char *ptr);
static uint32_t (*do_read_32) (unsigned char *ptr);
static void (*do_write_16) (unsigned char *ptr, uint16_t val);
static void (*do_write_32) (unsigned char *ptr, uint32_t val);
@@ -271,6 +272,9 @@ static void (*do_write_32) (unsigned char *ptr, uint32_t val);
static int ptr_size;
static int cu_version;
+/* The offset into the .debug_str_offsets section for the current CU. */
+static uint32_t str_offsets_base;
+
static inline uint16_t
buf_read_ule16 (unsigned char *data)
{
@@ -283,6 +287,18 @@ buf_read_ube16 (unsigned char *data)
return data[1] | (data[0] << 8);
}
+static inline uint32_t
+buf_read_ule24 (unsigned char *data)
+{
+ return data[0] | (data[1] << 8) | (data[2] << 16);
+}
+
+static inline uint32_t
+buf_read_ube24 (unsigned char *data)
+{
+ return data[2] | (data[1] << 8) | (data[0] << 16);
+}
+
static inline uint32_t
buf_read_ule32 (unsigned char *data)
{
@@ -544,10 +560,12 @@ setup_relbuf (DSO *dso, debug_section *sec, int *reltype)
/* Relocations against section symbols are uninteresting in REL. */
if (dso->shdr[i].sh_type == SHT_REL && sym.st_value == 0)
continue;
- /* Only consider relocations against .debug_str, .debug_line,
- .debug_line_str, and .debug_abbrev. */
+ /* Only consider relocations against .debug_str,
+ .debug_str_offsets, .debug_line, .debug_line_str, and
+ .debug_abbrev. */
if (sym.st_shndx == 0 ||
(sym.st_shndx != debug_sections[DEBUG_STR].sec
+ && sym.st_shndx != debug_sections[DEBUG_STR_OFFSETS].sec
&& sym.st_shndx != debug_sections[DEBUG_LINE].sec
&& sym.st_shndx != debug_sections[DEBUG_LINE_STR].sec
&& sym.st_shndx != debug_sections[DEBUG_ABBREV].sec))
@@ -684,6 +702,59 @@ update_rela_data (DSO *dso, struct debug_section *sec)
free (sec->relbuf);
}
+static inline uint32_t
+do_read_uleb128 (unsigned char *ptr)
+{
+ unsigned char *uleb_ptr = ptr;
+ return read_uleb128 (uleb_ptr);
+}
+
+static inline uint32_t
+do_read_str_form_relocated (DSO *dso, uint32_t form, unsigned char *ptr)
+{
+ uint32_t idx;
+ switch (form)
+ {
+ case DW_FORM_strp:
+ case DW_FORM_line_strp:
+ return do_read_32_relocated (ptr);
+
+ case DW_FORM_strx1:
+ idx = *ptr;
+ break;
+ case DW_FORM_strx2:
+ idx = do_read_16 (ptr);
+ break;
+ case DW_FORM_strx3:
+ idx = do_read_24 (ptr);
+ break;
+ case DW_FORM_strx4:
+ idx = do_read_32 (ptr);
+ break;
+ case DW_FORM_strx:
+ idx = do_read_uleb128 (ptr);
+ break;
+ default:
+ error (1, 0, "Unhandled string form DW_FORM_0x%x", form);
+ return -1;
+ }
+
+ unsigned char *str_off_ptr = debug_sections[DEBUG_STR_OFFSETS].data;
+ str_off_ptr += str_offsets_base;
+ str_off_ptr += idx * 4;
+
+ /* Switch rel reading... */
+ REL *old_relptr = relptr;
+ REL *old_relend = relend;
+ setup_relbuf(dso, &debug_sections[DEBUG_STR_OFFSETS], &reltype);
+
+ uint32_t str_off = do_read_32_relocated (str_off_ptr);
+
+ relptr = old_relptr;
+ relend = old_relend;
+ return str_off;
+}
+
struct abbrev_attr
{
unsigned int attr;
@@ -789,7 +860,12 @@ no_memory:
|| form == DW_FORM_addrx1
|| form == DW_FORM_addrx2
|| form == DW_FORM_addrx3
- || form == DW_FORM_addrx4)))
+ || form == DW_FORM_addrx4
+ || form == DW_FORM_strx
+ || form == DW_FORM_strx1
+ || form == DW_FORM_strx2
+ || form == DW_FORM_strx3
+ || form == DW_FORM_strx4)))
{
error (0, 0, "%s: Unknown DWARF DW_FORM_0x%x", dso->filename,
form);
@@ -1520,9 +1596,10 @@ edit_dwarf2_line (DSO *dso)
}
}
-/* Record or adjust (according to phase) DW_FORM_strp or DW_FORM_line_strp. */
+/* Record or adjust (according to phase) DW_FORM_strp or DW_FORM_line_strp.
+ Also handles DW_FORM_strx, but just for recording the (indexed) string. */
static void
-edit_strp (DSO *dso, bool line_strp, unsigned char *ptr, int phase,
+edit_strp (DSO *dso, uint32_t form, unsigned char *ptr, int phase,
bool handled_strp)
{
unsigned char *ptr_orig = ptr;
@@ -1537,16 +1614,19 @@ edit_strp (DSO *dso, bool line_strp, unsigned char *ptr, int phase,
recorded. */
if (! handled_strp)
{
- size_t idx = do_read_32_relocated (ptr);
- record_existing_string_entry_idx (line_strp, dso, idx);
+ size_t idx = do_read_str_form_relocated (dso, form, ptr);
+ record_existing_string_entry_idx (form == DW_FORM_line_strp,
+ dso, idx);
}
}
- else if (line_strp
- ? need_line_strp_update : need_strp_update) /* && phase == 1 */
+ else if ((form == DW_FORM_strp
+ || form == DW_FORM_line_strp) /* DW_FORM_strx stays the same. */
+ && (form == DW_FORM_line_strp
+ ? need_line_strp_update : need_strp_update)) /* && phase == 1 */
{
struct stridxentry *entry;
size_t idx, new_idx;
- struct strings *strings = (line_strp
+ struct strings *strings = (form == DW_FORM_line_strp
? &dso->debug_line_str : &dso->debug_str);
idx = do_read_32_relocated (ptr);
entry = string_find_entry (strings, idx);
@@ -1926,9 +2006,10 @@ read_dwarf5_line_entries (DSO *dso, unsigned char **ptrp,
switch (form)
{
+ /* Note we don't expect DW_FORM_strx in the line table. */
case DW_FORM_strp:
case DW_FORM_line_strp:
- edit_strp (dso, line_strp, *ptrp, phase, handled_strp);
+ edit_strp (dso, form, *ptrp, phase, handled_strp);
break;
}
@@ -2110,11 +2191,12 @@ find_new_list_offs (struct debug_lines *lines, size_t idx)
/* Read DW_FORM_strp or DW_FORM_line_strp collecting compilation directory. */
static void
-edit_attributes_str_comp_dir (bool line_strp, DSO *dso, unsigned char **ptrp,
+edit_attributes_str_comp_dir (uint32_t form, DSO *dso, unsigned char **ptrp,
int phase, char **comp_dirp, bool *handled_strpp)
{
const char *dir;
- size_t idx = do_read_32_relocated (*ptrp);
+ size_t idx = do_read_str_form_relocated (dso, form, *ptrp);
+ bool line_strp = form == DW_FORM_line_strp;
/* In phase zero we collect the comp_dir. */
if (phase == 0)
{
@@ -2245,20 +2327,29 @@ edit_attributes (DSO *dso, unsigned char *ptr, struct abbrev_tag *t, int phase)
}
}
}
- else if (form == DW_FORM_strp)
- edit_attributes_str_comp_dir (false /* line_strp */, dso,
+ else if (form == DW_FORM_strp
+ || form == DW_FORM_line_strp
+ || form == DW_FORM_strx
+ || form == DW_FORM_strx1
+ || form == DW_FORM_strx2
+ || form == DW_FORM_strx3
+ || form == DW_FORM_strx4)
+ edit_attributes_str_comp_dir (form, dso,
&ptr, phase, &comp_dir,
&handled_strp);
- else if (form == DW_FORM_line_strp)
- edit_attributes_str_comp_dir (true /* line_strp */, dso, &ptr,
- phase, &comp_dir, &handled_strp);
}
else if ((t->tag == DW_TAG_compile_unit
|| t->tag == DW_TAG_partial_unit)
&& ((form == DW_FORM_strp
&& debug_sections[DEBUG_STR].data)
|| (form == DW_FORM_line_strp
- && debug_sections[DEBUG_LINE_STR].data))
+ && debug_sections[DEBUG_LINE_STR].data)
+ || ((form == DW_FORM_strx
+ || form == DW_FORM_strx1
+ || form == DW_FORM_strx2
+ || form == DW_FORM_strx3
+ || form == DW_FORM_strx4)
+ && debug_sections[DEBUG_STR_OFFSETS].data))
&& t->attr[i].attr == DW_AT_name)
{
bool line_strp = form == DW_FORM_line_strp;
@@ -2267,7 +2358,7 @@ edit_attributes (DSO *dso, unsigned char *ptr, struct abbrev_tag *t, int phase)
unit. If starting with / it is a full path name.
Note that we don't handle DW_FORM_string in this
case. */
- size_t idx = do_read_32_relocated (ptr);
+ size_t idx = do_read_str_form_relocated (dso, form, ptr);
/* In phase zero we will look for a comp_dir to use. */
if (phase == 0)
@@ -2314,10 +2405,13 @@ edit_attributes (DSO *dso, unsigned char *ptr, struct abbrev_tag *t, int phase)
switch (form)
{
case DW_FORM_strp:
- edit_strp (dso, false /* line_strp */, ptr, phase, handled_strp);
- break;
case DW_FORM_line_strp:
- edit_strp (dso, true /* line_strp */, ptr, phase, handled_strp);
+ case DW_FORM_strx:
+ case DW_FORM_strx1:
+ case DW_FORM_strx2:
+ case DW_FORM_strx3:
+ case DW_FORM_strx4:
+ edit_strp (dso, form, ptr, phase, handled_strp);
break;
}
@@ -2404,6 +2498,8 @@ edit_info (DSO *dso, int phase, struct debug_section *sec)
uint32_t value;
htab_t abbrev;
struct abbrev_tag tag, *t;
+ int i;
+ bool first;
ptr = sec->data;
if (ptr == NULL)
@@ -2507,6 +2603,8 @@ edit_info (DSO *dso, int phase, struct debug_section *sec)
if (abbrev == NULL)
return 1;
+ first = true;
+ str_offsets_base = 0;
while (ptr < endcu)
{
tag.entry = read_uleb128 (ptr);
@@ -2521,6 +2619,30 @@ edit_info (DSO *dso, int phase, struct debug_section *sec)
return 1;
}
+ /* We need str_offsets_base before processing the CU. */
+ if (first)
+ {
+ first = false;
+ if (cu_version >= 5)
+ {
+ uint32_t form;
+ unsigned char *fptr = ptr;
+ // We will read this DIE again, save and reset rel reading
+ REL *old_relptr = relptr;
+ for (i = 0; i < t->nattr; ++i)
+ {
+ form = t->attr[i].form;
+ if (t->attr[i].attr == DW_AT_str_offsets_base)
+ {
+ str_offsets_base = do_read_32_relocated (fptr);
+ break;
+ }
+ skip_form (dso, &form, &fptr);
+ }
+ // Reset the rel reading...
+ relptr = old_relptr;
+ }
+ }
ptr = edit_attributes (dso, ptr, t, phase);
if (ptr == NULL)
break;
@@ -2554,6 +2676,41 @@ edit_dwarf2_any_str (DSO *dso, struct strings *strings, debug_section *secp)
strings->str_buf = strdata->d_buf;
}
+/* Rebuild .debug_str_offsets. */
+static void
+update_str_offsets (DSO *dso)
+{
+ unsigned char *ptr = debug_sections[DEBUG_STR_OFFSETS].data;
+ unsigned char *endp = ptr + debug_sections[DEBUG_STR_OFFSETS].size;
+
+ while (ptr < endp)
+ {
+ /* Read header, unit_length, version and padding. */
+ if (endp - ptr < 3 * 4)
+ break;
+ uint32_t unit_length = read_32 (ptr);
+ if (unit_length == 0xffffffff || endp - ptr < unit_length)
+ break;
+ unsigned char *endidxp = ptr + unit_length;
+ uint32_t version = read_32 (ptr);
+ if (version != 5)
+ break;
+ uint32_t padding = read_32 (ptr);
+ if (padding != 0)
+ break;
+
+ while (ptr < endidxp)
+ {
+ struct stridxentry *entry;
+ size_t idx, new_idx;
+ idx = do_read_32_relocated (ptr);
+ entry = string_find_entry (&dso->debug_str, idx);
+ new_idx = strent_offset (entry->entry);
+ write_32_relocated (ptr, new_idx);
+ }
+ }
+}
+
static int
edit_dwarf2 (DSO *dso)
{
@@ -2675,6 +2832,7 @@ edit_dwarf2 (DSO *dso)
if (dso->ehdr.e_ident[EI_DATA] == ELFDATA2LSB)
{
do_read_16 = buf_read_ule16;
+ do_read_24 = buf_read_ule24;
do_read_32 = buf_read_ule32;
do_write_16 = dwarf2_write_le16;
do_write_32 = dwarf2_write_le32;
@@ -2682,6 +2840,7 @@ edit_dwarf2 (DSO *dso)
else if (dso->ehdr.e_ident[EI_DATA] == ELFDATA2MSB)
{
do_read_16 = buf_read_ube16;
+ do_read_24 = buf_read_ube24;
do_read_32 = buf_read_ube32;
do_write_16 = dwarf2_write_be16;
do_write_32 = dwarf2_write_be32;
@@ -2997,6 +3156,15 @@ edit_dwarf2 (DSO *dso)
dirty_section (DEBUG_MACRO);
if (need_stmt_update || need_line_strp_update)
dirty_section (DEBUG_LINE);
+ if (need_strp_update && debug_sections[DEBUG_STR_OFFSETS].data != NULL)
+ {
+ setup_relbuf(dso, &debug_sections[DEBUG_STR_OFFSETS], &reltype);
+ rel_updated = false;
+ update_str_offsets (dso);
+ dirty_section (DEBUG_STR_OFFSETS);
+ if (rel_updated)
+ update_rela_data (dso, &debug_sections[DEBUG_STR_OFFSETS]);
+ }
/* Update any relocations addends we might have touched. */
if (info_rel_updated)
--
2.42.0
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