* [PATCH] kbuild: add CONFIG_VMLINUX_MAP expert option
@ 2021-02-24 10:52 Rasmus Villemoes
2021-03-04 22:47 ` Rasmus Villemoes
2021-03-05 5:59 ` Masahiro Yamada
0 siblings, 2 replies; 5+ messages in thread
From: Rasmus Villemoes @ 2021-02-24 10:52 UTC (permalink / raw)
To: Masahiro Yamada, Michal Marek
Cc: Rasmus Villemoes, linux-kernel, linux-kbuild
It can be quite useful to have ld emit a link map file, in order to
debug or verify that special sections end up where they are supposed
to, and to see what LD_DEAD_CODE_DATA_ELIMINATION manages to get rid
of.
The only reason I'm not just adding this unconditionally is that the
.map file can be rather large (several MB), and that's a waste of
space when one isn't interested in these things. Also hide the prompt
behind CONFIG_EXPERT.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
.gitignore | 1 +
Makefile | 3 ++-
lib/Kconfig.debug | 9 +++++++++
scripts/link-vmlinux.sh | 9 +++++++++
4 files changed, 21 insertions(+), 1 deletion(-)
diff --git a/.gitignore b/.gitignore
index 3af66272d6f1..d3038aff4485 100644
--- a/.gitignore
+++ b/.gitignore
@@ -58,6 +58,7 @@ modules.order
/TAGS
/linux
/vmlinux
+/vmlinux.map
/vmlinux.32
/vmlinux.symvers
/vmlinux-gdb.py
diff --git a/Makefile b/Makefile
index b18dbc634690..be6fbd99a214 100644
--- a/Makefile
+++ b/Makefile
@@ -1501,7 +1501,8 @@ endif # CONFIG_MODULES
# Directories & files removed with 'make clean'
CLEAN_FILES += include/ksym vmlinux.symvers \
modules.builtin modules.builtin.modinfo modules.nsdeps \
- compile_commands.json
+ compile_commands.json \
+ vmlinux.map
# Directories & files removed with 'make mrproper'
MRPROPER_FILES += include/config include/generated \
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 5ea0c1773b0a..d6af084c11ae 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -412,6 +412,15 @@ config VMLINUX_VALIDATION
depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT
default y
+config VMLINUX_MAP
+ bool "Generate vmlinux.map file when linking" if EXPERT
+ help
+ Selecting this option will pass "-Map=vmlinux.map" to ld
+ when linking vmlinux. That file can be useful for verifying
+ and debugging magic section games, and for seeing which
+ pieces of code get eliminated with
+ CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
+
config DEBUG_FORCE_WEAK_PER_CPU
bool "Force weak per-cpu definitions"
depends on DEBUG_KERNEL
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 3b261b0f74f0..bba58839db40 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -166,6 +166,12 @@ vmlinux_link()
strip_debug=-Wl,--strip-debug
fi
+ if [ -n "${CONFIG_VMLINUX_MAP}" ]; then
+ map_option="-Map=${output}.map"
+ else
+ map_option=""
+ fi
+
if [ "${SRCARCH}" != "um" ]; then
if [ -n "${CONFIG_LTO_CLANG}" ]; then
# Use vmlinux.o instead of performing the slow LTO
@@ -187,6 +193,7 @@ vmlinux_link()
${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \
${strip_debug#-Wl,} \
-o ${output} \
+ ${map_option} \
-T ${lds} ${objects}
else
objects="-Wl,--whole-archive \
@@ -200,6 +207,7 @@ vmlinux_link()
${CC} ${CFLAGS_vmlinux} \
${strip_debug} \
-o ${output} \
+ ${map_option:+-Wl,${map_option}} \
-Wl,-T,${lds} \
${objects} \
-lutil -lrt -lpthread
@@ -303,6 +311,7 @@ cleanup()
rm -f .tmp_vmlinux*
rm -f System.map
rm -f vmlinux
+ rm -f vmlinux.map
rm -f vmlinux.o
}
--
2.29.2
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] kbuild: add CONFIG_VMLINUX_MAP expert option
2021-02-24 10:52 [PATCH] kbuild: add CONFIG_VMLINUX_MAP expert option Rasmus Villemoes
@ 2021-03-04 22:47 ` Rasmus Villemoes
2021-03-05 5:59 ` Masahiro Yamada
1 sibling, 0 replies; 5+ messages in thread
From: Rasmus Villemoes @ 2021-03-04 22:47 UTC (permalink / raw)
To: Rasmus Villemoes, Masahiro Yamada, Michal Marek
Cc: linux-kernel, linux-kbuild
On 24/02/2021 11.52, Rasmus Villemoes wrote:
> It can be quite useful to have ld emit a link map file, in order to
> debug or verify that special sections end up where they are supposed
> to, and to see what LD_DEAD_CODE_DATA_ELIMINATION manages to get rid
> of.
>
> The only reason I'm not just adding this unconditionally is that the
> .map file can be rather large (several MB), and that's a waste of
> space when one isn't interested in these things. Also hide the prompt
> behind CONFIG_EXPERT.
ping
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] kbuild: add CONFIG_VMLINUX_MAP expert option
2021-02-24 10:52 [PATCH] kbuild: add CONFIG_VMLINUX_MAP expert option Rasmus Villemoes
2021-03-04 22:47 ` Rasmus Villemoes
@ 2021-03-05 5:59 ` Masahiro Yamada
2021-03-05 9:27 ` [PATCH v2] " Rasmus Villemoes
1 sibling, 1 reply; 5+ messages in thread
From: Masahiro Yamada @ 2021-03-05 5:59 UTC (permalink / raw)
To: Rasmus Villemoes
Cc: Michal Marek, Linux Kernel Mailing List, Linux Kbuild mailing list
On Wed, Feb 24, 2021 at 7:53 PM Rasmus Villemoes
<linux@rasmusvillemoes.dk> wrote:
>
> It can be quite useful to have ld emit a link map file, in order to
> debug or verify that special sections end up where they are supposed
> to, and to see what LD_DEAD_CODE_DATA_ELIMINATION manages to get rid
> of.
>
> The only reason I'm not just adding this unconditionally is that the
> .map file can be rather large (several MB), and that's a waste of
> space when one isn't interested in these things. Also hide the prompt
> behind CONFIG_EXPERT.
>
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> ---
> .gitignore | 1 +
> Makefile | 3 ++-
> lib/Kconfig.debug | 9 +++++++++
> scripts/link-vmlinux.sh | 9 +++++++++
> 4 files changed, 21 insertions(+), 1 deletion(-)
>
> diff --git a/.gitignore b/.gitignore
> index 3af66272d6f1..d3038aff4485 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -58,6 +58,7 @@ modules.order
> /TAGS
> /linux
> /vmlinux
> +/vmlinux.map
Could you move this one line below
so that vmlinux.map is placed between
vmlinux.32 and vmlinux.symvers ?
I know this list is not sorted...
> /vmlinux.32
> /vmlinux.symvers
> /vmlinux-gdb.py
Please add this to Documentation/dontdiff as well.
> diff --git a/Makefile b/Makefile
> index b18dbc634690..be6fbd99a214 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1501,7 +1501,8 @@ endif # CONFIG_MODULES
> # Directories & files removed with 'make clean'
> CLEAN_FILES += include/ksym vmlinux.symvers \
> modules.builtin modules.builtin.modinfo modules.nsdeps \
> - compile_commands.json
> + compile_commands.json \
> + vmlinux.map
Do you need this ?
You already added this to cleanup() of scripts/link-vmlinux.sh,
which is invoked from 'make clean'.
> # Directories & files removed with 'make mrproper'
> MRPROPER_FILES += include/config include/generated \
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 5ea0c1773b0a..d6af084c11ae 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -412,6 +412,15 @@ config VMLINUX_VALIDATION
> depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT
> default y
>
> +config VMLINUX_MAP
> + bool "Generate vmlinux.map file when linking" if EXPERT
Please use depends on EXPERT
because VMLINUX_MAP is not select or implied by anyone.
> + help
> + Selecting this option will pass "-Map=vmlinux.map" to ld
> + when linking vmlinux. That file can be useful for verifying
> + and debugging magic section games, and for seeing which
> + pieces of code get eliminated with
> + CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
> +
> config DEBUG_FORCE_WEAK_PER_CPU
> bool "Force weak per-cpu definitions"
> depends on DEBUG_KERNEL
> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index 3b261b0f74f0..bba58839db40 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -166,6 +166,12 @@ vmlinux_link()
> strip_debug=-Wl,--strip-debug
> fi
>
> + if [ -n "${CONFIG_VMLINUX_MAP}" ]; then
> + map_option="-Map=${output}.map"
> + else
> + map_option=""
> + fi
> +
For consistency, please do like strip_debug, that is,
define this as a local variable, and
set the value of the 'if' case.
> if [ "${SRCARCH}" != "um" ]; then
> if [ -n "${CONFIG_LTO_CLANG}" ]; then
> # Use vmlinux.o instead of performing the slow LTO
> @@ -187,6 +193,7 @@ vmlinux_link()
> ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \
> ${strip_debug#-Wl,} \
> -o ${output} \
> + ${map_option} \
> -T ${lds} ${objects}
> else
> objects="-Wl,--whole-archive \
> @@ -200,6 +207,7 @@ vmlinux_link()
> ${CC} ${CFLAGS_vmlinux} \
> ${strip_debug} \
> -o ${output} \
> + ${map_option:+-Wl,${map_option}} \
> -Wl,-T,${lds} \
> ${objects} \
> -lutil -lrt -lpthread
> @@ -303,6 +311,7 @@ cleanup()
> rm -f .tmp_vmlinux*
> rm -f System.map
> rm -f vmlinux
> + rm -f vmlinux.map
> rm -f vmlinux.o
> }
>
> --
> 2.29.2
>
--
Best Regards
Masahiro Yamada
^ permalink raw reply [flat|nested] 5+ messages in thread* [PATCH v2] kbuild: add CONFIG_VMLINUX_MAP expert option
2021-03-05 5:59 ` Masahiro Yamada
@ 2021-03-05 9:27 ` Rasmus Villemoes
2021-03-05 13:50 ` Masahiro Yamada
0 siblings, 1 reply; 5+ messages in thread
From: Rasmus Villemoes @ 2021-03-05 9:27 UTC (permalink / raw)
To: Jonathan Corbet, Masahiro Yamada, Michal Marek
Cc: Rasmus Villemoes, linux-kernel, linux-doc, linux-kbuild
It can be quite useful to have ld emit a link map file, in order to
debug or verify that special sections end up where they are supposed
to, and to see what LD_DEAD_CODE_DATA_ELIMINATION manages to get rid
of.
The only reason I'm not just adding this unconditionally is that the
.map file can be rather large (several MB), and that's a waste of
space when one isn't interested in these things. Also make it depend
on CONFIG_EXPERT.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
.gitignore | 1 +
Documentation/dontdiff | 1 +
lib/Kconfig.debug | 10 ++++++++++
scripts/link-vmlinux.sh | 8 ++++++++
4 files changed, 20 insertions(+)
diff --git a/.gitignore b/.gitignore
index 3af66272d6f1..3adea59847ce 100644
--- a/.gitignore
+++ b/.gitignore
@@ -59,6 +59,7 @@ modules.order
/linux
/vmlinux
/vmlinux.32
+/vmlinux.map
/vmlinux.symvers
/vmlinux-gdb.py
/vmlinuz
diff --git a/Documentation/dontdiff b/Documentation/dontdiff
index e361fc95ca29..ac42ad8d430d 100644
--- a/Documentation/dontdiff
+++ b/Documentation/dontdiff
@@ -252,6 +252,7 @@ vmlinux-*
vmlinux.aout
vmlinux.bin.all
vmlinux.lds
+vmlinux.map
vmlinux.symvers
vmlinuz
voffset.h
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 5ea0c1773b0a..663c1cd5018c 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -412,6 +412,16 @@ config VMLINUX_VALIDATION
depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT
default y
+config VMLINUX_MAP
+ bool "Generate vmlinux.map file when linking"
+ depends on EXPERT
+ help
+ Selecting this option will pass "-Map=vmlinux.map" to ld
+ when linking vmlinux. That file can be useful for verifying
+ and debugging magic section games, and for seeing which
+ pieces of code get eliminated with
+ CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
+
config DEBUG_FORCE_WEAK_PER_CPU
bool "Force weak per-cpu definitions"
depends on DEBUG_KERNEL
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 3b261b0f74f0..855fd4e6f03e 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -155,6 +155,7 @@ vmlinux_link()
local output=${1}
local objects
local strip_debug
+ local map_option
info LD ${output}
@@ -166,6 +167,10 @@ vmlinux_link()
strip_debug=-Wl,--strip-debug
fi
+ if [ -n "${CONFIG_VMLINUX_MAP}" ]; then
+ map_option="-Map=${output}.map"
+ fi
+
if [ "${SRCARCH}" != "um" ]; then
if [ -n "${CONFIG_LTO_CLANG}" ]; then
# Use vmlinux.o instead of performing the slow LTO
@@ -187,6 +192,7 @@ vmlinux_link()
${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \
${strip_debug#-Wl,} \
-o ${output} \
+ ${map_option} \
-T ${lds} ${objects}
else
objects="-Wl,--whole-archive \
@@ -200,6 +206,7 @@ vmlinux_link()
${CC} ${CFLAGS_vmlinux} \
${strip_debug} \
-o ${output} \
+ ${map_option:+-Wl,${map_option}} \
-Wl,-T,${lds} \
${objects} \
-lutil -lrt -lpthread
@@ -303,6 +310,7 @@ cleanup()
rm -f .tmp_vmlinux*
rm -f System.map
rm -f vmlinux
+ rm -f vmlinux.map
rm -f vmlinux.o
}
--
2.29.2
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH v2] kbuild: add CONFIG_VMLINUX_MAP expert option
2021-03-05 9:27 ` [PATCH v2] " Rasmus Villemoes
@ 2021-03-05 13:50 ` Masahiro Yamada
0 siblings, 0 replies; 5+ messages in thread
From: Masahiro Yamada @ 2021-03-05 13:50 UTC (permalink / raw)
To: Rasmus Villemoes
Cc: Jonathan Corbet, Michal Marek, Linux Kernel Mailing List,
open list:DOCUMENTATION, Linux Kbuild mailing list
On Fri, Mar 5, 2021 at 6:27 PM Rasmus Villemoes
<linux@rasmusvillemoes.dk> wrote:
>
> It can be quite useful to have ld emit a link map file, in order to
> debug or verify that special sections end up where they are supposed
> to, and to see what LD_DEAD_CODE_DATA_ELIMINATION manages to get rid
> of.
>
> The only reason I'm not just adding this unconditionally is that the
> .map file can be rather large (several MB), and that's a waste of
> space when one isn't interested in these things. Also make it depend
> on CONFIG_EXPERT.
>
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> ---
Applied to linux-kbuild.
Thanks.
> .gitignore | 1 +
> Documentation/dontdiff | 1 +
> lib/Kconfig.debug | 10 ++++++++++
> scripts/link-vmlinux.sh | 8 ++++++++
> 4 files changed, 20 insertions(+)
>
> diff --git a/.gitignore b/.gitignore
> index 3af66272d6f1..3adea59847ce 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -59,6 +59,7 @@ modules.order
> /linux
> /vmlinux
> /vmlinux.32
> +/vmlinux.map
> /vmlinux.symvers
> /vmlinux-gdb.py
> /vmlinuz
> diff --git a/Documentation/dontdiff b/Documentation/dontdiff
> index e361fc95ca29..ac42ad8d430d 100644
> --- a/Documentation/dontdiff
> +++ b/Documentation/dontdiff
> @@ -252,6 +252,7 @@ vmlinux-*
> vmlinux.aout
> vmlinux.bin.all
> vmlinux.lds
> +vmlinux.map
> vmlinux.symvers
> vmlinuz
> voffset.h
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 5ea0c1773b0a..663c1cd5018c 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -412,6 +412,16 @@ config VMLINUX_VALIDATION
> depends on STACK_VALIDATION && DEBUG_ENTRY && !PARAVIRT
> default y
>
> +config VMLINUX_MAP
> + bool "Generate vmlinux.map file when linking"
> + depends on EXPERT
> + help
> + Selecting this option will pass "-Map=vmlinux.map" to ld
> + when linking vmlinux. That file can be useful for verifying
> + and debugging magic section games, and for seeing which
> + pieces of code get eliminated with
> + CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
> +
> config DEBUG_FORCE_WEAK_PER_CPU
> bool "Force weak per-cpu definitions"
> depends on DEBUG_KERNEL
> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index 3b261b0f74f0..855fd4e6f03e 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -155,6 +155,7 @@ vmlinux_link()
> local output=${1}
> local objects
> local strip_debug
> + local map_option
>
> info LD ${output}
>
> @@ -166,6 +167,10 @@ vmlinux_link()
> strip_debug=-Wl,--strip-debug
> fi
>
> + if [ -n "${CONFIG_VMLINUX_MAP}" ]; then
> + map_option="-Map=${output}.map"
> + fi
> +
> if [ "${SRCARCH}" != "um" ]; then
> if [ -n "${CONFIG_LTO_CLANG}" ]; then
> # Use vmlinux.o instead of performing the slow LTO
> @@ -187,6 +192,7 @@ vmlinux_link()
> ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \
> ${strip_debug#-Wl,} \
> -o ${output} \
> + ${map_option} \
> -T ${lds} ${objects}
> else
> objects="-Wl,--whole-archive \
> @@ -200,6 +206,7 @@ vmlinux_link()
> ${CC} ${CFLAGS_vmlinux} \
> ${strip_debug} \
> -o ${output} \
> + ${map_option:+-Wl,${map_option}} \
> -Wl,-T,${lds} \
> ${objects} \
> -lutil -lrt -lpthread
> @@ -303,6 +310,7 @@ cleanup()
> rm -f .tmp_vmlinux*
> rm -f System.map
> rm -f vmlinux
> + rm -f vmlinux.map
> rm -f vmlinux.o
> }
>
> --
> 2.29.2
>
--
Best Regards
Masahiro Yamada
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-03-05 13:53 UTC | newest]
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2021-02-24 10:52 [PATCH] kbuild: add CONFIG_VMLINUX_MAP expert option Rasmus Villemoes
2021-03-04 22:47 ` Rasmus Villemoes
2021-03-05 5:59 ` Masahiro Yamada
2021-03-05 9:27 ` [PATCH v2] " Rasmus Villemoes
2021-03-05 13:50 ` Masahiro Yamada
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