<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/scripts/mod/modpost.c, branch v4.14.331</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>modpost: fix off by one in is_executable_section()</title>
<updated>2023-08-11T09:33:38+00:00</updated>
<author>
<name>Dan Carpenter</name>
<email>dan.carpenter@linaro.org</email>
</author>
<published>2023-06-08T08:23:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=7ee557590bac154d324de446d1cd0444988bd511'/>
<id>7ee557590bac154d324de446d1cd0444988bd511</id>
<content type='text'>
[ Upstream commit 3a3f1e573a105328a2cca45a7cfbebabbf5e3192 ]

The &gt; comparison should be &gt;= to prevent an out of bounds array
access.

Fixes: 52dc0595d540 ("modpost: handle relocations mismatch in __ex_table.")
Signed-off-by: Dan Carpenter &lt;dan.carpenter@linaro.org&gt;
Signed-off-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 3a3f1e573a105328a2cca45a7cfbebabbf5e3192 ]

The &gt; comparison should be &gt;= to prevent an out of bounds array
access.

Fixes: 52dc0595d540 ("modpost: handle relocations mismatch in __ex_table.")
Signed-off-by: Dan Carpenter &lt;dan.carpenter@linaro.org&gt;
Signed-off-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>modpost: fix section mismatch message for R_ARM_{PC24,CALL,JUMP24}</title>
<updated>2023-08-11T09:33:38+00:00</updated>
<author>
<name>Masahiro Yamada</name>
<email>masahiroy@kernel.org</email>
</author>
<published>2023-06-01T12:09:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=a2a121a1936e55a7688eeb6baf080e7672577a5e'/>
<id>a2a121a1936e55a7688eeb6baf080e7672577a5e</id>
<content type='text'>
[ Upstream commit 56a24b8ce6a7f9c4a21b2276a8644f6f3d8fc14d ]

addend_arm_rel() processes R_ARM_PC24, R_ARM_CALL, R_ARM_JUMP24 in a
wrong way.

Here, test code.

[test code for R_ARM_JUMP24]

  .section .init.text,"ax"
  bar:
          bx      lr

  .section .text,"ax"
  .globl foo
  foo:
          b       bar

[test code for R_ARM_CALL]

  .section .init.text,"ax"
  bar:
          bx      lr

  .section .text,"ax"
  .globl foo
  foo:
          push    {lr}
          bl      bar
          pop     {pc}

If you compile it with ARM multi_v7_defconfig, modpost will show the
symbol name, (unknown).

  WARNING: modpost: vmlinux.o: section mismatch in reference: foo (section: .text) -&gt; (unknown) (section: .init.text)

(You need to use GNU linker instead of LLD to reproduce it.)

Fix the code to make modpost show the correct symbol name.

I imported (with adjustment) sign_extend32() from include/linux/bitops.h.

The '+8' is the compensation for pc-relative instruction. It is
documented in "ELF for the Arm Architecture" [1].

  "If the relocation is pc-relative then compensation for the PC bias
  (the PC value is 8 bytes ahead of the executing instruction in Arm
  state and 4 bytes in Thumb state) must be encoded in the relocation
  by the object producer."

[1]: https://github.com/ARM-software/abi-aa/blob/main/aaelf32/aaelf32.rst

Fixes: 56a974fa2d59 ("kbuild: make better section mismatch reports on arm")
Fixes: 6e2e340b59d2 ("ARM: 7324/1: modpost: Fix section warnings for ARM for many compilers")
Signed-off-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 56a24b8ce6a7f9c4a21b2276a8644f6f3d8fc14d ]

addend_arm_rel() processes R_ARM_PC24, R_ARM_CALL, R_ARM_JUMP24 in a
wrong way.

Here, test code.

[test code for R_ARM_JUMP24]

  .section .init.text,"ax"
  bar:
          bx      lr

  .section .text,"ax"
  .globl foo
  foo:
          b       bar

[test code for R_ARM_CALL]

  .section .init.text,"ax"
  bar:
          bx      lr

  .section .text,"ax"
  .globl foo
  foo:
          push    {lr}
          bl      bar
          pop     {pc}

If you compile it with ARM multi_v7_defconfig, modpost will show the
symbol name, (unknown).

  WARNING: modpost: vmlinux.o: section mismatch in reference: foo (section: .text) -&gt; (unknown) (section: .init.text)

(You need to use GNU linker instead of LLD to reproduce it.)

Fix the code to make modpost show the correct symbol name.

I imported (with adjustment) sign_extend32() from include/linux/bitops.h.

The '+8' is the compensation for pc-relative instruction. It is
documented in "ELF for the Arm Architecture" [1].

  "If the relocation is pc-relative then compensation for the PC bias
  (the PC value is 8 bytes ahead of the executing instruction in Arm
  state and 4 bytes in Thumb state) must be encoded in the relocation
  by the object producer."

[1]: https://github.com/ARM-software/abi-aa/blob/main/aaelf32/aaelf32.rst

Fixes: 56a974fa2d59 ("kbuild: make better section mismatch reports on arm")
Fixes: 6e2e340b59d2 ("ARM: 7324/1: modpost: Fix section warnings for ARM for many compilers")
Signed-off-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>modpost: fix section mismatch message for R_ARM_ABS32</title>
<updated>2023-08-11T09:33:38+00:00</updated>
<author>
<name>Masahiro Yamada</name>
<email>masahiroy@kernel.org</email>
</author>
<published>2023-06-01T12:09:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=eaf31306a9f5a728099d81a70113dd22d165f6f6'/>
<id>eaf31306a9f5a728099d81a70113dd22d165f6f6</id>
<content type='text'>
[ Upstream commit b7c63520f6703a25eebb4f8138fed764fcae1c6f ]

addend_arm_rel() processes R_ARM_ABS32 in a wrong way.

Here, test code.

  [test code 1]

    #include &lt;linux/init.h&gt;

    int __initdata foo;
    int get_foo(void) { return foo; }

If you compile it with ARM versatile_defconfig, modpost will show the
symbol name, (unknown).

  WARNING: modpost: vmlinux.o: section mismatch in reference: get_foo (section: .text) -&gt; (unknown) (section: .init.data)

(You need to use GNU linker instead of LLD to reproduce it.)

If you compile it for other architectures, modpost will show the correct
symbol name.

  WARNING: modpost: vmlinux.o: section mismatch in reference: get_foo (section: .text) -&gt; foo (section: .init.data)

For R_ARM_ABS32, addend_arm_rel() sets r-&gt;r_addend to a wrong value.

I just mimicked the code in arch/arm/kernel/module.c.

However, there is more difficulty for ARM.

Here, test code.

  [test code 2]

    #include &lt;linux/init.h&gt;

    int __initdata foo;
    int get_foo(void) { return foo; }

    int __initdata bar;
    int get_bar(void) { return bar; }

With this commit applied, modpost will show the following messages
for ARM versatile_defconfig:

  WARNING: modpost: vmlinux.o: section mismatch in reference: get_foo (section: .text) -&gt; foo (section: .init.data)
  WARNING: modpost: vmlinux.o: section mismatch in reference: get_bar (section: .text) -&gt; foo (section: .init.data)

The reference from 'get_bar' to 'foo' seems wrong.

I have no solution for this because it is true in assembly level.

In the following output, relocation at 0x1c is no longer associated
with 'bar'. The two relocation entries point to the same symbol, and
the offset to 'bar' is encoded in the instruction 'r0, [r3, #4]'.

  Disassembly of section .text:

  00000000 &lt;get_foo&gt;:
     0: e59f3004          ldr     r3, [pc, #4]   @ c &lt;get_foo+0xc&gt;
     4: e5930000          ldr     r0, [r3]
     8: e12fff1e          bx      lr
     c: 00000000          .word   0x00000000

  00000010 &lt;get_bar&gt;:
    10: e59f3004          ldr     r3, [pc, #4]   @ 1c &lt;get_bar+0xc&gt;
    14: e5930004          ldr     r0, [r3, #4]
    18: e12fff1e          bx      lr
    1c: 00000000          .word   0x00000000

  Relocation section '.rel.text' at offset 0x244 contains 2 entries:
   Offset     Info    Type            Sym.Value  Sym. Name
  0000000c  00000c02 R_ARM_ABS32       00000000   .init.data
  0000001c  00000c02 R_ARM_ABS32       00000000   .init.data

When find_elf_symbol() gets into a situation where relsym-&gt;st_name is
zero, there is no guarantee to get the symbol name as written in C.

I am keeping the current logic because it is useful in many architectures,
but the symbol name is not always correct depending on the optimization.
I left some comments in find_tosym().

Fixes: 56a974fa2d59 ("kbuild: make better section mismatch reports on arm")
Signed-off-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit b7c63520f6703a25eebb4f8138fed764fcae1c6f ]

addend_arm_rel() processes R_ARM_ABS32 in a wrong way.

Here, test code.

  [test code 1]

    #include &lt;linux/init.h&gt;

    int __initdata foo;
    int get_foo(void) { return foo; }

If you compile it with ARM versatile_defconfig, modpost will show the
symbol name, (unknown).

  WARNING: modpost: vmlinux.o: section mismatch in reference: get_foo (section: .text) -&gt; (unknown) (section: .init.data)

(You need to use GNU linker instead of LLD to reproduce it.)

If you compile it for other architectures, modpost will show the correct
symbol name.

  WARNING: modpost: vmlinux.o: section mismatch in reference: get_foo (section: .text) -&gt; foo (section: .init.data)

For R_ARM_ABS32, addend_arm_rel() sets r-&gt;r_addend to a wrong value.

I just mimicked the code in arch/arm/kernel/module.c.

However, there is more difficulty for ARM.

Here, test code.

  [test code 2]

    #include &lt;linux/init.h&gt;

    int __initdata foo;
    int get_foo(void) { return foo; }

    int __initdata bar;
    int get_bar(void) { return bar; }

With this commit applied, modpost will show the following messages
for ARM versatile_defconfig:

  WARNING: modpost: vmlinux.o: section mismatch in reference: get_foo (section: .text) -&gt; foo (section: .init.data)
  WARNING: modpost: vmlinux.o: section mismatch in reference: get_bar (section: .text) -&gt; foo (section: .init.data)

The reference from 'get_bar' to 'foo' seems wrong.

I have no solution for this because it is true in assembly level.

In the following output, relocation at 0x1c is no longer associated
with 'bar'. The two relocation entries point to the same symbol, and
the offset to 'bar' is encoded in the instruction 'r0, [r3, #4]'.

  Disassembly of section .text:

  00000000 &lt;get_foo&gt;:
     0: e59f3004          ldr     r3, [pc, #4]   @ c &lt;get_foo+0xc&gt;
     4: e5930000          ldr     r0, [r3]
     8: e12fff1e          bx      lr
     c: 00000000          .word   0x00000000

  00000010 &lt;get_bar&gt;:
    10: e59f3004          ldr     r3, [pc, #4]   @ 1c &lt;get_bar+0xc&gt;
    14: e5930004          ldr     r0, [r3, #4]
    18: e12fff1e          bx      lr
    1c: 00000000          .word   0x00000000

  Relocation section '.rel.text' at offset 0x244 contains 2 entries:
   Offset     Info    Type            Sym.Value  Sym. Name
  0000000c  00000c02 R_ARM_ABS32       00000000   .init.data
  0000001c  00000c02 R_ARM_ABS32       00000000   .init.data

When find_elf_symbol() gets into a situation where relsym-&gt;st_name is
zero, there is no guarantee to get the symbol name as written in C.

I am keeping the current logic because it is useful in many architectures,
but the symbol name is not always correct depending on the optimization.
I left some comments in find_tosym().

Fixes: 56a974fa2d59 ("kbuild: make better section mismatch reports on arm")
Signed-off-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>modpost: fix section mismatch check for exported init/exit sections</title>
<updated>2022-07-02T14:18:10+00:00</updated>
<author>
<name>Masahiro Yamada</name>
<email>masahiroy@kernel.org</email>
</author>
<published>2022-06-10T18:32:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=ac0d234fe54bd895f3472e6221db72eb0a4b833d'/>
<id>ac0d234fe54bd895f3472e6221db72eb0a4b833d</id>
<content type='text'>
commit 28438794aba47a27e922857d27b31b74e8559143 upstream.

Since commit f02e8a6596b7 ("module: Sort exported symbols"),
EXPORT_SYMBOL* is placed in the individual section ___ksymtab(_gpl)+&lt;sym&gt;
(3 leading underscores instead of 2).

Since then, modpost cannot detect the bad combination of EXPORT_SYMBOL
and __init/__exit.

Fix the .fromsec field.

Fixes: f02e8a6596b7 ("module: Sort exported symbols")
Signed-off-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Reviewed-by: Nick Desaulniers &lt;ndesaulniers@google.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 28438794aba47a27e922857d27b31b74e8559143 upstream.

Since commit f02e8a6596b7 ("module: Sort exported symbols"),
EXPORT_SYMBOL* is placed in the individual section ___ksymtab(_gpl)+&lt;sym&gt;
(3 leading underscores instead of 2).

Since then, modpost cannot detect the bad combination of EXPORT_SYMBOL
and __init/__exit.

Fix the .fromsec field.

Fixes: f02e8a6596b7 ("module: Sort exported symbols")
Signed-off-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Reviewed-by: Nick Desaulniers &lt;ndesaulniers@google.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>modpost: fix undefined behavior of is_arm_mapping_symbol()</title>
<updated>2022-06-14T14:54:00+00:00</updated>
<author>
<name>Masahiro Yamada</name>
<email>masahiroy@kernel.org</email>
</author>
<published>2022-05-23T16:46:22+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=35b2527da36bf541dd7581d65a9826cbd18236c6'/>
<id>35b2527da36bf541dd7581d65a9826cbd18236c6</id>
<content type='text'>
[ Upstream commit d6b732666a1bae0df3c3ae06925043bba34502b1 ]

The return value of is_arm_mapping_symbol() is unpredictable when "$"
is passed in.

strchr(3) says:
  The strchr() and strrchr() functions return a pointer to the matched
  character or NULL if the character is not found. The terminating null
  byte is considered part of the string, so that if c is specified as
  '\0', these functions return a pointer to the terminator.

When str[1] is '\0', strchr("axtd", str[1]) is not NULL, and str[2] is
referenced (i.e. buffer overrun).

Test code
---------

  char str1[] = "abc";
  char str2[] = "ab";

  strcpy(str1, "$");
  strcpy(str2, "$");

  printf("test1: %d\n", is_arm_mapping_symbol(str1));
  printf("test2: %d\n", is_arm_mapping_symbol(str2));

Result
------

  test1: 0
  test2: 1

Signed-off-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Reviewed-by: Nick Desaulniers &lt;ndesaulniers@google.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit d6b732666a1bae0df3c3ae06925043bba34502b1 ]

The return value of is_arm_mapping_symbol() is unpredictable when "$"
is passed in.

strchr(3) says:
  The strchr() and strrchr() functions return a pointer to the matched
  character or NULL if the character is not found. The terminating null
  byte is considered part of the string, so that if c is specified as
  '\0', these functions return a pointer to the terminator.

When str[1] is '\0', strchr("axtd", str[1]) is not NULL, and str[2] is
referenced (i.e. buffer overrun).

Test code
---------

  char str1[] = "abc";
  char str2[] = "ab";

  strcpy(str1, "$");
  strcpy(str2, "$");

  printf("test1: %d\n", is_arm_mapping_symbol(str1));
  printf("test2: %d\n", is_arm_mapping_symbol(str2));

Result
------

  test1: 0
  test2: 1

Signed-off-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Reviewed-by: Nick Desaulniers &lt;ndesaulniers@google.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>modpost: fix removing numeric suffixes</title>
<updated>2022-06-14T14:53:57+00:00</updated>
<author>
<name>Alexander Lobakin</name>
<email>alexandr.lobakin@intel.com</email>
</author>
<published>2022-05-24T15:27:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=ffd8470494c2ae11d24bc52c9bcfbd80c5afbbbb'/>
<id>ffd8470494c2ae11d24bc52c9bcfbd80c5afbbbb</id>
<content type='text'>
[ Upstream commit b5beffa20d83c4e15306c991ffd00de0d8628338 ]

With the `-z unique-symbol` linker flag or any similar mechanism,
it is possible to trigger the following:

ERROR: modpost: "param_set_uint.0" [vmlinux] is a static EXPORT_SYMBOL

The reason is that for now the condition from remove_dot():

if (m &amp;&amp; (s[n + m] == '.' || s[n + m] == 0))

which was designed to test if it's a dot or a '\0' after the suffix
is never satisfied.
This is due to that `s[n + m]` always points to the last digit of a
numeric suffix, not on the symbol next to it (from a custom debug
print added to modpost):

param_set_uint.0, s[n + m] is '0', s[n + m + 1] is '\0'

So it's off-by-one and was like that since 2014.

Fix this for the sake of any potential upcoming features, but don't
bother stable-backporting, as it's well hidden -- apart from that
LD flag, it can be triggered only with GCC LTO which never landed
upstream.

Fixes: fcd38ed0ff26 ("scripts: modpost: fix compilation warning")
Signed-off-by: Alexander Lobakin &lt;alexandr.lobakin@intel.com&gt;
Reviewed-by: Petr Mladek &lt;pmladek@suse.com&gt;
Signed-off-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit b5beffa20d83c4e15306c991ffd00de0d8628338 ]

With the `-z unique-symbol` linker flag or any similar mechanism,
it is possible to trigger the following:

ERROR: modpost: "param_set_uint.0" [vmlinux] is a static EXPORT_SYMBOL

The reason is that for now the condition from remove_dot():

if (m &amp;&amp; (s[n + m] == '.' || s[n + m] == 0))

which was designed to test if it's a dot or a '\0' after the suffix
is never satisfied.
This is due to that `s[n + m]` always points to the last digit of a
numeric suffix, not on the symbol next to it (from a custom debug
print added to modpost):

param_set_uint.0, s[n + m] is '0', s[n + m + 1] is '\0'

So it's off-by-one and was like that since 2014.

Fix this for the sake of any potential upcoming features, but don't
bother stable-backporting, as it's well hidden -- apart from that
LD flag, it can be triggered only with GCC LTO which never landed
upstream.

Fixes: fcd38ed0ff26 ("scripts: modpost: fix compilation warning")
Signed-off-by: Alexander Lobakin &lt;alexandr.lobakin@intel.com&gt;
Reviewed-by: Petr Mladek &lt;pmladek@suse.com&gt;
Signed-off-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>modpost: skip ELF local symbols during section mismatch check</title>
<updated>2019-12-17T19:38:30+00:00</updated>
<author>
<name>Paul Walmsley</name>
<email>paul.walmsley@sifive.com</email>
</author>
<published>2018-11-21T21:14:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=4d64f26e2a30dd4aab623182a38cbb90b5460b73'/>
<id>4d64f26e2a30dd4aab623182a38cbb90b5460b73</id>
<content type='text'>
[ Upstream commit a4d26f1a0958bb1c2b60c6f1e67c6f5d43e2647b ]

During development of a serial console driver with a gcc 8.2.0
toolchain for RISC-V, the following modpost warning appeared:

----
WARNING: vmlinux.o(.data+0x19b10): Section mismatch in reference from the variable .LANCHOR1 to the function .init.text:sifive_serial_console_setup()
The variable .LANCHOR1 references
the function __init sifive_serial_console_setup()
If the reference is valid then annotate the
variable with __init* or __refdata (see linux/init.h) or name the variable:
*_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console
----

".LANCHOR1" is an ELF local symbol, automatically created by gcc's section
anchor generation code:

https://gcc.gnu.org/onlinedocs/gccint/Anchored-Addresses.html

https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/varasm.c;h=cd9591a45617464946dcf9a126dde277d9de9804;hb=9fb89fa845c1b2e0a18d85ada0b077c84508ab78#l7473

This was verified by compiling the kernel with -fno-section-anchors
and observing that the ".LANCHOR1" ELF local symbol disappeared, and
modpost no longer warned about the section mismatch.  The serial
driver code idiom triggering the warning is standard Linux serial
driver practice that has a specific whitelist inclusion in modpost.c.

I'm neither a modpost nor an ELF expert, but naively, it doesn't seem
useful for modpost to report section mismatch warnings caused by ELF
local symbols by default.  Local symbols have compiler-generated
names, and thus bypass modpost's whitelisting algorithm, which relies
on the presence of a non-autogenerated symbol name.  This increases
the likelihood that false positive warnings will be generated (as in
the above case).

Thus, disable section mismatch reporting on ELF local symbols.  The
rationale here is similar to that of commit 2e3a10a1551d ("ARM: avoid
ARM binutils leaking ELF local symbols") and of similar code already
present in modpost.c:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/mod/modpost.c?h=v4.19-rc4&amp;id=7876320f88802b22d4e2daf7eb027dd14175a0f8#n1256

This third version of the patch implements a suggestion from Masahiro
Yamada &lt;yamada.masahiro@socionext.com&gt; to restructure the code as an
additional pattern matching step inside secref_whitelist(), and
further improves the patch description.

Signed-off-by: Paul Walmsley &lt;paul.walmsley@sifive.com&gt;
Signed-off-by: Paul Walmsley &lt;paul@pwsan.com&gt;
Acked-by: Sam Ravnborg &lt;sam@ravnborg.org&gt;
Signed-off-by: Masahiro Yamada &lt;yamada.masahiro@socionext.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit a4d26f1a0958bb1c2b60c6f1e67c6f5d43e2647b ]

During development of a serial console driver with a gcc 8.2.0
toolchain for RISC-V, the following modpost warning appeared:

----
WARNING: vmlinux.o(.data+0x19b10): Section mismatch in reference from the variable .LANCHOR1 to the function .init.text:sifive_serial_console_setup()
The variable .LANCHOR1 references
the function __init sifive_serial_console_setup()
If the reference is valid then annotate the
variable with __init* or __refdata (see linux/init.h) or name the variable:
*_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console
----

".LANCHOR1" is an ELF local symbol, automatically created by gcc's section
anchor generation code:

https://gcc.gnu.org/onlinedocs/gccint/Anchored-Addresses.html

https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/varasm.c;h=cd9591a45617464946dcf9a126dde277d9de9804;hb=9fb89fa845c1b2e0a18d85ada0b077c84508ab78#l7473

This was verified by compiling the kernel with -fno-section-anchors
and observing that the ".LANCHOR1" ELF local symbol disappeared, and
modpost no longer warned about the section mismatch.  The serial
driver code idiom triggering the warning is standard Linux serial
driver practice that has a specific whitelist inclusion in modpost.c.

I'm neither a modpost nor an ELF expert, but naively, it doesn't seem
useful for modpost to report section mismatch warnings caused by ELF
local symbols by default.  Local symbols have compiler-generated
names, and thus bypass modpost's whitelisting algorithm, which relies
on the presence of a non-autogenerated symbol name.  This increases
the likelihood that false positive warnings will be generated (as in
the above case).

Thus, disable section mismatch reporting on ELF local symbols.  The
rationale here is similar to that of commit 2e3a10a1551d ("ARM: avoid
ARM binutils leaking ELF local symbols") and of similar code already
present in modpost.c:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/mod/modpost.c?h=v4.19-rc4&amp;id=7876320f88802b22d4e2daf7eb027dd14175a0f8#n1256

This third version of the patch implements a suggestion from Masahiro
Yamada &lt;yamada.masahiro@socionext.com&gt; to restructure the code as an
additional pattern matching step inside secref_whitelist(), and
further improves the patch description.

Signed-off-by: Paul Walmsley &lt;paul.walmsley@sifive.com&gt;
Signed-off-by: Paul Walmsley &lt;paul@pwsan.com&gt;
Acked-by: Sam Ravnborg &lt;sam@ravnborg.org&gt;
Signed-off-by: Masahiro Yamada &lt;yamada.masahiro@socionext.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>kbuild: modversions: Fix relative CRC byte order interpretation</title>
<updated>2019-04-03T04:25:17+00:00</updated>
<author>
<name>Fredrik Noring</name>
<email>noring@nocrew.org</email>
</author>
<published>2019-03-27T18:12:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=e75c894d8186c5bc86b40a6eebf887f6ce5ebb75'/>
<id>e75c894d8186c5bc86b40a6eebf887f6ce5ebb75</id>
<content type='text'>
commit 54a7151b1496cddbb7a83546b7998103e98edc88 upstream.

Fix commit 56067812d5b0 ("kbuild: modversions: add infrastructure for
emitting relative CRCs") where CRCs are interpreted in host byte order
rather than proper kernel byte order. The bug is conditional on
CONFIG_MODULE_REL_CRCS.

For example, when loading a BE module into a BE kernel compiled with a LE
system, the error "disagrees about version of symbol module_layout" is
produced. A message such as "Found checksum D7FA6856 vs module 5668FAD7"
will be given with debug enabled, which indicates an obvious endian
problem within __kcrctab within the kernel image.

The general solution is to use the macro TO_NATIVE, as is done in
similar cases throughout modpost.c. With this correction it has been
verified that a BE kernel compiled with a LE system accepts BE modules.

This change has also been verified with a LE kernel compiled with a LE
system, in which case TO_NATIVE returns its value unmodified since the
byte orders match. This is by far the common case.

Fixes: 56067812d5b0 ("kbuild: modversions: add infrastructure for emitting relative CRCs")
Signed-off-by: Fredrik Noring &lt;noring@nocrew.org&gt;
Cc: stable@vger.kernel.org
Signed-off-by: Masahiro Yamada &lt;yamada.masahiro@socionext.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 54a7151b1496cddbb7a83546b7998103e98edc88 upstream.

Fix commit 56067812d5b0 ("kbuild: modversions: add infrastructure for
emitting relative CRCs") where CRCs are interpreted in host byte order
rather than proper kernel byte order. The bug is conditional on
CONFIG_MODULE_REL_CRCS.

For example, when loading a BE module into a BE kernel compiled with a LE
system, the error "disagrees about version of symbol module_layout" is
produced. A message such as "Found checksum D7FA6856 vs module 5668FAD7"
will be given with debug enabled, which indicates an obvious endian
problem within __kcrctab within the kernel image.

The general solution is to use the macro TO_NATIVE, as is done in
similar cases throughout modpost.c. With this correction it has been
verified that a BE kernel compiled with a LE system accepts BE modules.

This change has also been verified with a LE kernel compiled with a LE
system, in which case TO_NATIVE returns its value unmodified since the
byte orders match. This is by far the common case.

Fixes: 56067812d5b0 ("kbuild: modversions: add infrastructure for emitting relative CRCs")
Signed-off-by: Fredrik Noring &lt;noring@nocrew.org&gt;
Cc: stable@vger.kernel.org
Signed-off-by: Masahiro Yamada &lt;yamada.masahiro@socionext.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>modpost: validate symbol names also in find_elf_symbol</title>
<updated>2019-02-12T18:45:59+00:00</updated>
<author>
<name>Sami Tolvanen</name>
<email>samitolvanen@google.com</email>
</author>
<published>2018-10-23T22:15:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=20a7ded03f97005cd282f419bf35f22ab2ec74fc'/>
<id>20a7ded03f97005cd282f419bf35f22ab2ec74fc</id>
<content type='text'>
[ Upstream commit 5818c683a619c534c113e1f66d24f636defc29bc ]

If an ARM mapping symbol shares an address with a valid symbol,
find_elf_symbol can currently return the mapping symbol instead, as the
symbol is not validated. This can result in confusing warnings:

  WARNING: vmlinux.o(.text+0x18f4028): Section mismatch in reference
  from the function set_reset_devices() to the variable .init.text:$x.0

This change adds a call to is_valid_name to find_elf_symbol, similarly
to how it's already used in find_elf_symbol2.

Signed-off-by: Sami Tolvanen &lt;samitolvanen@google.com&gt;
Signed-off-by: Masahiro Yamada &lt;yamada.masahiro@socionext.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 5818c683a619c534c113e1f66d24f636defc29bc ]

If an ARM mapping symbol shares an address with a valid symbol,
find_elf_symbol can currently return the mapping symbol instead, as the
symbol is not validated. This can result in confusing warnings:

  WARNING: vmlinux.o(.text+0x18f4028): Section mismatch in reference
  from the function set_reset_devices() to the variable .init.text:$x.0

This change adds a call to is_valid_name to find_elf_symbol, similarly
to how it's already used in find_elf_symbol2.

Signed-off-by: Sami Tolvanen &lt;samitolvanen@google.com&gt;
Signed-off-by: Masahiro Yamada &lt;yamada.masahiro@socionext.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86, modpost: Replace last remnants of RETPOLINE with CONFIG_RETPOLINE</title>
<updated>2019-01-16T21:07:10+00:00</updated>
<author>
<name>WANG Chao</name>
<email>chao.wang@ucloud.cn</email>
</author>
<published>2018-12-10T16:37:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=64ac5483a1b187f4e3fa47c65ba53546f9089bd6'/>
<id>64ac5483a1b187f4e3fa47c65ba53546f9089bd6</id>
<content type='text'>
commit e4f358916d528d479c3c12bd2fd03f2d5a576380 upstream.

Commit

  4cd24de3a098 ("x86/retpoline: Make CONFIG_RETPOLINE depend on compiler support")

replaced the RETPOLINE define with CONFIG_RETPOLINE checks. Remove the
remaining pieces.

 [ bp: Massage commit message. ]

Fixes: 4cd24de3a098 ("x86/retpoline: Make CONFIG_RETPOLINE depend on compiler support")
Signed-off-by: WANG Chao &lt;chao.wang@ucloud.cn&gt;
Signed-off-by: Borislav Petkov &lt;bp@suse.de&gt;
Reviewed-by: Zhenzhong Duan &lt;zhenzhong.duan@oracle.com&gt;
Reviewed-by: Masahiro Yamada &lt;yamada.masahiro@socionext.com&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Cc: Andi Kleen &lt;ak@linux.intel.com&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Andy Lutomirski &lt;luto@kernel.org&gt;
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Cc: David Woodhouse &lt;dwmw@amazon.co.uk&gt;
Cc: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Cc: Jessica Yu &lt;jeyu@kernel.org&gt;
Cc: Jiri Kosina &lt;jkosina@suse.cz&gt;
Cc: Kees Cook &lt;keescook@chromium.org&gt;
Cc: Konrad Rzeszutek Wilk &lt;konrad.wilk@oracle.com&gt;
Cc: Luc Van Oostenryck &lt;luc.vanoostenryck@gmail.com&gt;
Cc: Michal Marek &lt;michal.lkml@markovi.net&gt;
Cc: Miguel Ojeda &lt;miguel.ojeda.sandonis@gmail.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Tim Chen &lt;tim.c.chen@linux.intel.com&gt;
Cc: Vasily Gorbik &lt;gor@linux.ibm.com&gt;
Cc: linux-kbuild@vger.kernel.org
Cc: srinivas.eeda@oracle.com
Cc: stable &lt;stable@vger.kernel.org&gt;
Cc: x86-ml &lt;x86@kernel.org&gt;
Link: https://lkml.kernel.org/r/20181210163725.95977-1-chao.wang@ucloud.cn
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit e4f358916d528d479c3c12bd2fd03f2d5a576380 upstream.

Commit

  4cd24de3a098 ("x86/retpoline: Make CONFIG_RETPOLINE depend on compiler support")

replaced the RETPOLINE define with CONFIG_RETPOLINE checks. Remove the
remaining pieces.

 [ bp: Massage commit message. ]

Fixes: 4cd24de3a098 ("x86/retpoline: Make CONFIG_RETPOLINE depend on compiler support")
Signed-off-by: WANG Chao &lt;chao.wang@ucloud.cn&gt;
Signed-off-by: Borislav Petkov &lt;bp@suse.de&gt;
Reviewed-by: Zhenzhong Duan &lt;zhenzhong.duan@oracle.com&gt;
Reviewed-by: Masahiro Yamada &lt;yamada.masahiro@socionext.com&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Cc: Andi Kleen &lt;ak@linux.intel.com&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Andy Lutomirski &lt;luto@kernel.org&gt;
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Cc: David Woodhouse &lt;dwmw@amazon.co.uk&gt;
Cc: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Cc: Jessica Yu &lt;jeyu@kernel.org&gt;
Cc: Jiri Kosina &lt;jkosina@suse.cz&gt;
Cc: Kees Cook &lt;keescook@chromium.org&gt;
Cc: Konrad Rzeszutek Wilk &lt;konrad.wilk@oracle.com&gt;
Cc: Luc Van Oostenryck &lt;luc.vanoostenryck@gmail.com&gt;
Cc: Michal Marek &lt;michal.lkml@markovi.net&gt;
Cc: Miguel Ojeda &lt;miguel.ojeda.sandonis@gmail.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Tim Chen &lt;tim.c.chen@linux.intel.com&gt;
Cc: Vasily Gorbik &lt;gor@linux.ibm.com&gt;
Cc: linux-kbuild@vger.kernel.org
Cc: srinivas.eeda@oracle.com
Cc: stable &lt;stable@vger.kernel.org&gt;
Cc: x86-ml &lt;x86@kernel.org&gt;
Link: https://lkml.kernel.org/r/20181210163725.95977-1-chao.wang@ucloud.cn
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
</feed>
