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MSP430: Fix alignment of __*_array_start symbols in default linker script

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__{preinit,init,fini}_array_start symbols must be word aligned in
linker scripts. If the section preceding the __*_array_start symbol
has an odd size, then a NULL byte will be present between the start
symbol and the .*_array section itself, when the section gets
automatically word-aligned.

This results in a branch to an invalid address when the CRT startup
code tries to run through the functions listed in the array sections.

Some MSP430 linker scripts do not align the __*_array start symbols, so
this added warning will catch that problem and help the user avoid
the potential incorrect execution of the program.

ld/ChangeLog:

	* emultempl/msp430.em (input_section_exists): New.
	(check_array_section_alignment): New.
	(gld${EMULATION_NAME}_finish): New.
	* scripttempl/elf32msp430.sc: Add ALIGN directives before the
	definition of __*_array_start symbols.
	* testsuite/ld-msp430-elf/finiarray-warn.ld: New test.
	* testsuite/ld-msp430-elf/finiarray-warn.r: New test.
	* testsuite/ld-msp430-elf/initarray-nowarn.ld: New test.
	* testsuite/ld-msp430-elf/initarray-warn.ld: New test.
	* testsuite/ld-msp430-elf/initarray-warn.r: New test.
	* testsuite/ld-msp430-elf/initarray.s: New test.
	* testsuite/ld-msp430-elf/msp430-elf.exp: Run new tests.
	* testsuite/ld-msp430-elf/preinitarray-warn.ld: New test.
	* testsuite/ld-msp430-elf/preinitarray-warn.r: New test.
This commit is contained in:
Jozef Lawrynowicz
2020-08-28 13:56:53 +01:00
parent 87870682f3
commit 64b63c2993
13 changed files with 320 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
ld/ChangeLog
View File

@@ -1,3 +1,20 @@
2020-08-28 Jozef Lawrynowicz <jozef.l@mittosystems.com>
* emultempl/msp430.em (input_section_exists): New.
(check_array_section_alignment): New.
(gld${EMULATION_NAME}_finish): New.
* scripttempl/elf32msp430.sc: Add ALIGN directives before the
definition of __*_array_start symbols.
* testsuite/ld-msp430-elf/finiarray-warn.ld: New test.
* testsuite/ld-msp430-elf/finiarray-warn.r: New test.
* testsuite/ld-msp430-elf/initarray-nowarn.ld: New test.
* testsuite/ld-msp430-elf/initarray-warn.ld: New test.
* testsuite/ld-msp430-elf/initarray-warn.r: New test.
* testsuite/ld-msp430-elf/initarray.s: New test.
* testsuite/ld-msp430-elf/msp430-elf.exp: Run new tests.
* testsuite/ld-msp430-elf/preinitarray-warn.ld: New test.
* testsuite/ld-msp430-elf/preinitarray-warn.r: New test.
2020-08-28 Jozef Lawrynowicz <jozef.l@mittosystems.com>
* ldmisc.c (vfinfo): Support new "%pU" format specifier.

81
ld/emultempl/msp430.em
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@@ -826,6 +826,85 @@ msp430_elf_after_allocation (void)
gld${EMULATION_NAME}_after_allocation ();
}
/* Return TRUE if a non-debug input section in L has positive size and matches
the given name. */
static int
input_section_exists (lang_statement_union_type * l, const char * name)
{
while (l != NULL)
{
switch (l->header.type)
{
case lang_input_section_enum:
if ((l->input_section.section->flags & SEC_ALLOC)
&& l->input_section.section->size > 0
&& !strcmp (l->input_section.section->name, name))
return TRUE;
break;
case lang_wild_statement_enum:
if (input_section_exists (l->wild_statement.children.head, name))
return TRUE;
break;
default:
break;
}
l = l->header.next;
}
return FALSE;
}
/* Some MSP430 linker scripts do not include ALIGN directives to ensure
__preinit_array_start, __init_array_start or __fini_array_start are word
aligned.
If __*_array_start symbols are not word aligned, the code in crt0 to run
through the array and call the functions will crash.
To avoid warning unnecessarily when the .*_array sections are not being
used for running constructors/destructors, only emit the warning if
the associated section exists and has size. */
static void
check_array_section_alignment (void)
{
int i;
lang_output_section_statement_type * rodata_sec;
lang_output_section_statement_type * rodata2_sec;
const char * array_names[3][2] = { { ".init_array", "__init_array_start" },
{ ".preinit_array", "__preinit_array_start" },
{ ".fini_array", "__fini_array_start" } };
/* .{preinit,init,fini}_array could be in either .rodata or .rodata2. */
rodata_sec = lang_output_section_find (".rodata");
rodata2_sec = lang_output_section_find (".rodata2");
if (rodata_sec == NULL && rodata2_sec == NULL)
return;
/* There are 3 .*_array sections which must be checked for alignment. */
for (i = 0; i < 3; i++)
{
struct bfd_link_hash_entry * sym;
if (((rodata_sec && input_section_exists (rodata_sec->children.head,
array_names[i][0]))
|| (rodata2_sec && input_section_exists (rodata2_sec->children.head,
array_names[i][0])))
&& (sym = bfd_link_hash_lookup (link_info.hash, array_names[i][1],
FALSE, FALSE, TRUE))
&& sym->type == bfd_link_hash_defined
&& sym->u.def.value % 2)
{
einfo ("%P: warning: \"%s\" symbol (%pU) is not word aligned\n",
array_names[i][1], NULL);
}
}
}
static void
gld${EMULATION_NAME}_finish (void)
{
finish_default ();
check_array_section_alignment ();
}
struct ld_emulation_xfer_struct ld_${EMULATION_NAME}_emulation =
{
${LDEMUL_BEFORE_PARSE-gld${EMULATION_NAME}_before_parse},
@@ -842,7 +921,7 @@ struct ld_emulation_xfer_struct ld_${EMULATION_NAME}_emulation =
${LDEMUL_GET_SCRIPT-gld${EMULATION_NAME}_get_script},
"${EMULATION_NAME}",
"${OUTPUT_FORMAT}",
${LDEMUL_FINISH-finish_default},
gld${EMULATION_NAME}_finish,
${LDEMUL_CREATE_OUTPUT_SECTION_STATEMENTS-NULL},
${LDEMUL_OPEN_DYNAMIC_ARCHIVE-NULL},
${LDEMUL_PLACE_ORPHAN-gld${EMULATION_NAME}_place_orphan},

3
ld/scripttempl/elf32msp430.sc
View File

@@ -208,15 +208,18 @@ SECTIONS
KEEP (*(.gcc_except_table)) *(.gcc_except_table.*)
. = ALIGN(2);
PROVIDE (__preinit_array_start = .);
KEEP (*(.preinit_array))
PROVIDE (__preinit_array_end = .);
. = ALIGN(2);
PROVIDE (__init_array_start = .);
KEEP (*(SORT(.init_array.*)))
KEEP (*(.init_array))
PROVIDE (__init_array_end = .);
. = ALIGN(2);
PROVIDE (__fini_array_start = .);
KEEP (*(.fini_array))
KEEP (*(SORT(.fini_array.*)))

46
ld/testsuite/ld-msp430-elf/finiarray-warn.ld Normal file
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@@ -0,0 +1,46 @@
/* Script for ld testsuite */
OUTPUT_ARCH(msp430)
ENTRY(_start)
SECTIONS
{
.text :
{
PROVIDE (_start = .);
. = ALIGN(2);
*(.text .stub .text.* .gnu.linkonce.t.* .text:*)
}
.rodata :
{
*(.rodata.* .rodata)
. = ALIGN(2);
PROVIDE (__preinit_array_start = .);
KEEP (*(SORT(.preinit_array.*)))
KEEP (*(.preinit_array))
PROVIDE (__preinit_array_end = .);
. = ALIGN(2);
PROVIDE (__init_array_start = .);
KEEP (*(SORT(.init_array.*)))
KEEP (*(.init_array))
PROVIDE (__init_array_end = .);
. = ALIGN(2);
. += 1;
PROVIDE (__fini_array_start = .);
KEEP (*(SORT(.fini_array.*)))
KEEP (*(.fini_array))
PROVIDE (__fini_array_end = .);
}
.data :
{
. = ALIGN(2);
*(.data.* .data)
}
.bss :
{
. = ALIGN(2);
*(.bss.* .bss)
}
}

1
ld/testsuite/ld-msp430-elf/finiarray-warn.r Normal file
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@@ -0,0 +1 @@
.*warning: "__fini_array_start" symbol \(finiarray-warn.ld\) is not word aligned

45
ld/testsuite/ld-msp430-elf/initarray-nowarn.ld Normal file
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@@ -0,0 +1,45 @@
/* Script for ld testsuite */
OUTPUT_ARCH(msp430)
ENTRY(_start)
SECTIONS
{
.text :
{
PROVIDE (_start = .);
. = ALIGN(2);
*(.text .stub .text.* .gnu.linkonce.t.* .text:*)
}
.rodata :
{
*(.rodata.* .rodata)
. = ALIGN(2);
PROVIDE (__preinit_array_start = .);
KEEP (*(SORT(.preinit_array.*)))
KEEP (*(.preinit_array))
PROVIDE (__preinit_array_end = .);
. = ALIGN(2);
PROVIDE (__init_array_start = .);
KEEP (*(SORT(.init_array.*)))
KEEP (*(.init_array))
PROVIDE (__init_array_end = .);
. = ALIGN(2);
PROVIDE (__fini_array_start = .);
KEEP (*(SORT(.fini_array.*)))
KEEP (*(.fini_array))
PROVIDE (__fini_array_end = .);
}
.data :
{
. = ALIGN(2);
*(.data.* .data)
}
.bss :
{
. = ALIGN(2);
*(.bss.* .bss)
}
}

0
ld/testsuite/ld-msp430-elf/initarray-nowarn.r Normal file
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46
ld/testsuite/ld-msp430-elf/initarray-warn.ld Normal file
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@@ -0,0 +1,46 @@
/* Script for ld testsuite */
OUTPUT_ARCH(msp430)
ENTRY(_start)
SECTIONS
{
.text :
{
PROVIDE (_start = .);
. = ALIGN(2);
*(.text .stub .text.* .gnu.linkonce.t.* .text:*)
}
.rodata :
{
*(.rodata.* .rodata)
. = ALIGN(2);
PROVIDE (__preinit_array_start = .);
KEEP (*(SORT(.preinit_array.*)))
KEEP (*(.preinit_array))
PROVIDE (__preinit_array_end = .);
. = ALIGN(2);
. += 1;
PROVIDE (__init_array_start = .);
KEEP (*(SORT(.init_array.*)))
KEEP (*(.init_array))
PROVIDE (__init_array_end = .);
. = ALIGN(2);
PROVIDE (__fini_array_start = .);
KEEP (*(SORT(.fini_array.*)))
KEEP (*(.fini_array))
PROVIDE (__fini_array_end = .);
}
.data :
{
. = ALIGN(2);
*(.data.* .data)
}
.bss :
{
. = ALIGN(2);
*(.bss.* .bss)
}
}

1
ld/testsuite/ld-msp430-elf/initarray-warn.r Normal file
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@@ -0,0 +1 @@
.*warning: "__init_array_start" symbol \(initarray-warn.ld\) is not word aligned

21
ld/testsuite/ld-msp430-elf/initarray.s Normal file
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@@ -0,0 +1,21 @@
.text
.section .preinit_array,"aw"
.short 42
.section .init_array,"aw"
.short 43
.section .fini_array,"aw"
.short 44
.text
.global main
.type main, @function
main:
MOV #__preinit_array_start, R8
MOV #__init_array_start, R9
MOV #__fini_array_start, R10
CALL @R8
CALL @R9
CALL @R10
RET

13
ld/testsuite/ld-msp430-elf/msp430-elf.exp
View File

@@ -163,6 +163,19 @@ set msp430warntests {
{{ld warn-no-lower-data.r}} "warn-no-lower-data"}
}
set msp430arraytests {
{ "Warn when __preinit_array_start is not word aligned" "-T preinitarray-warn.ld" "" ""
{initarray.s} {{ld preinitarray-warn.r}} "preinitarray-warn"}
{ "Warn when __init_array_start is not word aligned" "-T initarray-warn.ld" "" ""
{initarray.s} {{ld initarray-warn.r}} "initarray-warn"}
{ "Warn when __fini_array_start is not word aligned" "-T finiarray-warn.ld" "" ""
{initarray.s} {{ld finiarray-warn.r}} "finiarray-warn"}
{ "Don't warn when __{preinit,init,fini}_array_start are word aligned" "-T initarray-nowarn.ld" "" ""
{initarray.s} {{ld initarray-nowarn.r}} "initarray-nowarn"}
}
run_ld_link_tests $msp430arraytests
# Don't run further tests when msp430 ISA is selected
if {[string match "*-mcpu=msp430 *" [board_info [target_info name] multilib_flags]]
|| [string match "*-mcpu=msp430" [board_info [target_info name] multilib_flags]]} {

46
ld/testsuite/ld-msp430-elf/preinitarray-warn.ld Normal file
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@@ -0,0 +1,46 @@
/* Script for ld testsuite */
OUTPUT_ARCH(msp430)
ENTRY(_start)
SECTIONS
{
.text :
{
PROVIDE (_start = .);
. = ALIGN(2);
*(.text .stub .text.* .gnu.linkonce.t.* .text:*)
}
.rodata :
{
*(.rodata.* .rodata)
. = ALIGN(2);
. += 1;
PROVIDE (__preinit_array_start = .);
KEEP (*(SORT(.preinit_array.*)))
KEEP (*(.preinit_array))
PROVIDE (__preinit_array_end = .);
. = ALIGN(2);
PROVIDE (__init_array_start = .);
KEEP (*(SORT(.init_array.*)))
KEEP (*(.init_array))
PROVIDE (__init_array_end = .);
. = ALIGN(2);
PROVIDE (__fini_array_start = .);
KEEP (*(SORT(.fini_array.*)))
KEEP (*(.fini_array))
PROVIDE (__fini_array_end = .);
}
.data :
{
. = ALIGN(2);
*(.data.* .data)
}
.bss :
{
. = ALIGN(2);
*(.bss.* .bss)
}
}

1
ld/testsuite/ld-msp430-elf/preinitarray-warn.r Normal file
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@@ -0,0 +1 @@
.*warning: "__preinit_array_start" symbol \(preinitarray-warn.ld\) is not word aligned