modpost.c: Add .text.unlikely to TEXT_SECTIONS

Recent gcc's may place functions into the .text.unlikely section and we need to check this section as well for section mismatches now otherwise we may have false negatives for this test.

Cc Rusty Russell <[email protected]>

Cc Greg Kroah-Hartman <[email protected]>

Cc [email protected]

Cc [email protected]

Signed-off-by Tom Rini <[email protected]>

---
 scripts/mod/modpost.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

scripts/mod/modpost.c +1 -1

index ff36c50..13ff12f 100644
@@ -880,7 +880,7 @@ static void check_section(const char *modname, struct elf_info *elf,
 #define ALL_EXIT_SECTIONS EXIT_SECTIONS, ALL_XXXEXIT_SECTIONS
 
 #define DATA_SECTIONS ".data$", ".data.rel$"
-#define TEXT_SECTIONS ".text$"
+#define TEXT_SECTIONS ".text$", ".text.unlikely$"
 
 #define INIT_SECTIONS      ".init.*"
 #define CPU_INIT_SECTIONS  ".cpuinit.*"

Signature · 1 line

1.7.9.5

Quoted 3 lines · Tom Rini

Recent gcc's may place functions into the .text.unlikely section and we need to check this section as well for section mismatches now otherwise we may have false negatives for this test.

Hmm, I don't think it's all that recent, is it? I can find it back to gcc 4.0.4:

`-freorder-functions'
Reorder functions in the object file in order to improve code locality. This is implemented by using special subsections .text.hot' for most frequently executed functions and .text.unlikely' for unlikely executed functions. Reordering is done by the linker so object file format must support named sections and linker must place them in a reasonable way.

Also profile feedback must be available in to make this option effective. See `-fprofile-arcs' for details.

Enabled at levels -O2', -O3', `-Os'.

The comment is the same in in gcc 4.7.

So is your real issue that this section is generated with -fprofile-arcs, or has something changed with gcc 4.8, or...?

Quoted 24 lines · Rusty Russell

Quoted 3 lines · Tom Rini

Recent gcc's may place functions into the .text.unlikely section and we need to check this section as well for section mismatches now otherwise we may have false negatives for this test.

Hmm, I don't think it's all that recent, is it? I can find it back to gcc 4.0.4:

`-freorder-functions'
Reorder functions in the object file in order to improve code locality. This is implemented by using special subsections .text.hot' for most frequently executed functions and .text.unlikely' for unlikely executed functions. Reordering is done by the linker so object file format must support named sections and linker must place them in a reasonable way.

Also profile feedback must be available in to make this option effective. See `-fprofile-arcs' for details.

Enabled at levels -O2', -O3', `-Os'.

The comment is the same in in gcc 4.7.

Quoted 2 lines

So is your real issue that this section is generated with -fprofile-arcs, or has something changed with gcc 4.8, or...?

I've started seeing this with Linaro based 4.7 toolchains. I can go back through their releases and see when it starts showing up there if it helps. I didn't add .text.hot as I didn't have that section at all, fwiw.

Quoted 28 lines · Tom Rini

Quoted 26 lines · Rusty Russell

Quoted 3 lines · Tom Rini

Recent gcc's may place functions into the .text.unlikely section and we need to check this section as well for section mismatches now otherwise we may have false negatives for this test.

Hmm, I don't think it's all that recent, is it? I can find it back to gcc 4.0.4:

`-freorder-functions'
Reorder functions in the object file in order to improve code locality. This is implemented by using special subsections .text.hot' for most frequently executed functions and .text.unlikely' for unlikely executed functions. Reordering is done by the linker so object file format must support named sections and linker must place them in a reasonable way.

Also profile feedback must be available in to make this option effective. See `-fprofile-arcs' for details.

Enabled at levels -O2', -O3', `-Os'.

The comment is the same in in gcc 4.7.

So is your real issue that this section is generated with -fprofile-arcs, or has something changed with gcc 4.8, or...?

Quoted 4 lines

I've started seeing this with Linaro based 4.7 toolchains. I can go back through their releases and see when it starts showing up there if it helps. I didn't add .text.hot as I didn't have that section at all, fwiw.

Weird, did you turn on CONFIG_GCOV_KERNEL? AFAICT you shouldn't see this section without that.

Quoted 34 lines · Rusty Russell

Quoted 32 lines · Tom Rini

Quoted 20 lines · Rusty Russell

Quoted 3 lines · Tom Rini

Recent gcc's may place functions into the .text.unlikely section and we need to check this section as well for section mismatches now otherwise we may have false negatives for this test.

Hmm, I don't think it's all that recent, is it? I can find it back to gcc 4.0.4:

`-freorder-functions'
Reorder functions in the object file in order to improve code locality. This is implemented by using special subsections .text.hot' for most frequently executed functions and .text.unlikely' for unlikely executed functions. Reordering is done by the linker so object file format must support named sections and linker must place them in a reasonable way.

Also profile feedback must be available in to make this option effective. See `-fprofile-arcs' for details.

Quoted 6 lines

Enabled at levels -O2', -O3', `-Os'.

The comment is the same in in gcc 4.7.

So is your real issue that this section is generated with -fprofile-arcs, or has something changed with gcc 4.8, or...?

I've started seeing this with Linaro based 4.7 toolchains. I can go back through their releases and see when it starts showing up there if it helps. I didn't add .text.hot as I didn't have that section at all, fwiw.

Quoted 2 lines

Weird, did you turn on CONFIG_GCOV_KERNEL? AFAICT you shouldn't see this section without that.

Nope, CONFIG_GCOV_KERNEL is off. Must be related to whatever flags the Linaro folks set as default on -O2 (at least in their 2013.03 release), after reading over one of the .o.cmd files in the build.

Do you want me to re-word the commit message a bit or ? Thanks!

Quoted 38 lines · Tom Rini

Quoted 36 lines · Rusty Russell

Quoted 25 lines · Tom Rini

Quoted 24 lines · Rusty Russell

Quoted 3 lines · Tom Rini

Recent gcc's may place functions into the .text.unlikely section and we need to check this section as well for section mismatches now otherwise we may have false negatives for this test.

Hmm, I don't think it's all that recent, is it? I can find it back to gcc 4.0.4:

`-freorder-functions'
Reorder functions in the object file in order to improve code locality. This is implemented by using special subsections .text.hot' for most frequently executed functions and .text.unlikely' for unlikely executed functions. Reordering is done by the linker so object file format must support named sections and linker must place them in a reasonable way.

Also profile feedback must be available in to make this option effective. See `-fprofile-arcs' for details.

Enabled at levels -O2', -O3', `-Os'.

The comment is the same in in gcc 4.7.

Quoted 7 lines

Quoted 2 lines

So is your real issue that this section is generated with -fprofile-arcs, or has something changed with gcc 4.8, or...?

I've started seeing this with Linaro based 4.7 toolchains. I can go back through their releases and see when it starts showing up there if it helps. I didn't add .text.hot as I didn't have that section at all, fwiw.

Weird, did you turn on CONFIG_GCOV_KERNEL? AFAICT you shouldn't see this section without that.

Quoted 5 lines

Nope, CONFIG_GCOV_KERNEL is off. Must be related to whatever flags the Linaro folks set as default on -O2 (at least in their 2013.03 release), after reading over one of the .o.cmd files in the build.

Do you want me to re-word the commit message a bit or ? Thanks!

I poked around, and every Linaro binary I can grab (2012.01 and gcc 4.6 to 2013.04 and gcc 4.8) has this behaviour.