kbuild: link-vmlinux.sh: Make output file name configurable

In order to introduce an intermediate, non-stripped vmlinux build that
can be used by other build steps as an input, pass the output file

kbuild: link-vmlinux.sh: Make output file name configurable

In order to introduce an intermediate, non-stripped vmlinux build that
can be used by other build steps as an input, pass the output file name
to link-vmlinux.sh via its command line.

Signed-off-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Masahiro Yamada <[email protected]>

show more ...

kbuild: do not generate .tmp_vmlinux*.map when CONFIG_VMLINUX_MAP=y

Commit 5cc124720461 ("kbuild: add CONFIG_VMLINUX_MAP expert option")
mentioned that "the .map file can be rather large (several MB

kbuild: do not generate .tmp_vmlinux*.map when CONFIG_VMLINUX_MAP=y

Commit 5cc124720461 ("kbuild: add CONFIG_VMLINUX_MAP expert option")
mentioned 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."

If that is the case, generating map files for the intermediate
tmp_vmlinux* files is also a waste of space. It is unlikely that
anyone would be interested in the .tmp_vmlinux*.map files.

This commit stops passing the -Map= option when linking the .tmp_vmlinux*
intermediates.

I also hard-coded the file name 'vmlinux.map' instead of ${output}.map
because a later commit will introduce vmlinux.unstripped but I want to
keep the current name of the map file.

Signed-off-by: Masahiro Yamada <[email protected]>
Acked-by: Ard Biesheuvel <[email protected]>

show more ...

scripts/sorttable: Zero out weak functions in mcount_loc table

When a function is annotated as "weak" and is overridden, the code is not
removed. If it is traced, the fentry/mcount location in the w

scripts/sorttable: Zero out weak functions in mcount_loc table

When a function is annotated as "weak" and is overridden, the code is not
removed. If it is traced, the fentry/mcount location in the weak function
will be referenced by the "__mcount_loc" section. This will then be added
to the available_filter_functions list. Since only the address of the
functions are listed, to find the name to show, a search of kallsyms is
used.

Since kallsyms will return the function by simply finding the function
that the address is after but before the next function, an address of a
weak function will show up as the function before it. This is because
kallsyms does not save names of weak functions. This has caused issues in
the past, as now the traced weak function will be listed in
available_filter_functions with the name of the function before it.

At best, this will cause the previous function's name to be listed twice.
At worse, if the previous function was marked notrace, it will now show up
as a function that can be traced. Note that it only shows up that it can
be traced but will not be if enabled, which causes confusion.

https://lore.kernel.org/all/[email protected]/

The commit b39181f7c6907 ("ftrace: Add FTRACE_MCOUNT_MAX_OFFSET to avoid
adding weak function") was a workaround to this by checking the function
address before printing its name. If the address was too far from the
function given by the name then instead of printing the name it would
print: __ftrace_invalid_address___<invalid-offset>

The real issue is that these invalid addresses are listed in the ftrace
table look up which available_filter_functions is derived from. A place
holder must be listed in that file because set_ftrace_filter may take a
series of indexes into that file instead of names to be able to do O(1)
lookups to enable filtering (many tools use this method).

Even if kallsyms saved the size of the function, it does not remove the
need of having these place holders. The real solution is to not add a weak
function into the ftrace table in the first place.

To solve this, the sorttable.c code that sorts the mcount regions during
the build is modified to take a "nm -S vmlinux" input, sort it, and any
function listed in the mcount_loc section that is not within a boundary of
the function list given by nm is considered a weak function and is zeroed
out.

Note, this does not mean they will remain zero when booting as KASLR
will still shift those addresses. To handle this, the entries in the
mcount_loc section will be ignored if they are zero or match the
kaslr_offset() value.

Before:

~# grep __ftrace_invalid_address___ /sys/kernel/tracing/available_filter_functions | wc -l
551

After:

~# grep __ftrace_invalid_address___ /sys/kernel/tracing/available_filter_functions | wc -l
0

Cc: bpf <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Nicolas Schier <[email protected]>
Cc: Zheng Yejian <[email protected]>
Cc: Martin Kelly <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Alexander Gordeev <[email protected]>
Link: https://lore.kernel.org/[email protected]
Signed-off-by: Steven Rostedt (Google) <[email protected]>

show more ...

kallsyms: Remove KALLSYMS_ABSOLUTE_PERCPU

x86-64 was the only user.

Signed-off-by: Brian Gerst <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Reviewed-by: Ard Biesheuvel <ardb@ke

kallsyms: Remove KALLSYMS_ABSOLUTE_PERCPU

x86-64 was the only user.

Signed-off-by: Brian Gerst <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Reviewed-by: Ard Biesheuvel <[email protected]>
Cc: Linus Torvalds <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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kbuild/btf: Propagate CONFIG_WERROR to resolve_btfids

Use CONFIG_WERROR to also fail on warnings emitted by resolve_btfids.
Allow the CI bots to prevent the introduction of new warnings.

Signed-off

kbuild/btf: Propagate CONFIG_WERROR to resolve_btfids

Use CONFIG_WERROR to also fail on warnings emitted by resolve_btfids.
Allow the CI bots to prevent the introduction of new warnings.

Signed-off-by: Thomas Weißschuh <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

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kbuild: rename .tmp_vmlinux.kallsyms0.syms to .tmp_vmlinux0.syms

Change the naming for consistency.

While at this, fix the comments in scripts/link-vmlinux.sh.

Signed-off-by: Sedat Dilek <sedat.di

kbuild: rename .tmp_vmlinux.kallsyms0.syms to .tmp_vmlinux0.syms

Change the naming for consistency.

While at this, fix the comments in scripts/link-vmlinux.sh.

Signed-off-by: Sedat Dilek <[email protected]>
Signed-off-by: Masahiro Yamada <[email protected]>

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kbuild: add generic support for built-in boot DTBs

Some architectures embed boot DTBs in vmlinux. A potential issue for
these architectures is a race condition during parallel builds because
Kbuild

kbuild: add generic support for built-in boot DTBs

Some architectures embed boot DTBs in vmlinux. A potential issue for
these architectures is a race condition during parallel builds because
Kbuild descends into arch/*/boot/dts/ twice.

One build thread is initiated by the 'dtbs' target, which is a
prerequisite of the 'all' target in the top-level Makefile:

ifdef CONFIG_OF_EARLY_FLATTREE
all: dtbs
endif

For architectures that support the built-in boot dtb, arch/*/boot/dts/
is visited also during the ordinary directory traversal in order to
build obj-y objects that wrap DTBs.

Since these build threads are unaware of each other, they can run
simultaneously during parallel builds.

This commit introduces a generic build rule to scripts/Makefile.vmlinux
to support embedded boot DTBs in a race-free way. Architectures that
want to use this rule need to select CONFIG_GENERIC_BUILTIN_DTB.

After the migration, Makefiles under arch/*/boot/dts/ will be visited
only once to build only *.dtb files.

This change also aims to unify the CONFIG options used for built-in DTBs
support. Currently, different architectures use different CONFIG options
for the same purposes.

With this commit, the CONFIG options will be unified as follows:

- CONFIG_GENERIC_BUILTIN_DTB

This enables the generic rule for built-in boot DTBs. This will be
renamed to CONFIG_BUILTIN_DTB after all architectures migrate to the
generic rule.

- CONFIG_BUILTIN_DTB_NAME

This specifies the path to the embedded DTB.
(relative to arch/*/boot/dts/)

- CONFIG_BUILTIN_DTB_ALL

If this is enabled, all DTB files compiled under arch/*/boot/dts/ are
embedded into vmlinux. Only used by MIPS.

Signed-off-by: Masahiro Yamada <[email protected]>

show more ...

kbuild: Add generic hook for architectures to use before the final vmlinux link

On powerpc, we would like to be able to make a pass on vmlinux.o and
generate a new object file to be linked into vmli

kbuild: Add generic hook for architectures to use before the final vmlinux link

On powerpc, we would like to be able to make a pass on vmlinux.o and
generate a new object file to be linked into vmlinux. Add a generic pass
in Makefile.vmlinux that architectures can use for this purpose.

Architectures need to select CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX and must
provide arch/<arch>/tools/Makefile with .arch.vmlinux.o target, which
will be invoked prior to the final vmlinux link step.

Acked-by: Masahiro Yamada <[email protected]>
Signed-off-by: Naveen N Rao <[email protected]>
Signed-off-by: Hari Bathini <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://patch.msgid.link/[email protected]

show more ...

btf: move pahole check in scripts/link-vmlinux.sh to lib/Kconfig.debug

When DEBUG_INFO_DWARF5 is selected, pahole 1.21+ is required to enable
DEBUG_INFO_BTF.

When DEBUG_INFO_DWARF4 or DEBUG_INFO_DW

btf: move pahole check in scripts/link-vmlinux.sh to lib/Kconfig.debug

When DEBUG_INFO_DWARF5 is selected, pahole 1.21+ is required to enable
DEBUG_INFO_BTF.

When DEBUG_INFO_DWARF4 or DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT is selected,
DEBUG_INFO_BTF can be enabled without pahole installed, but a build error
will occur in scripts/link-vmlinux.sh:

LD .tmp_vmlinux1
BTF: .tmp_vmlinux1: pahole (pahole) is not available
Failed to generate BTF for vmlinux
Try to disable CONFIG_DEBUG_INFO_BTF

We did not guard DEBUG_INFO_BTF by PAHOLE_VERSION when previously
discussed [1].

However, commit 613fe1692377 ("kbuild: Add CONFIG_PAHOLE_VERSION")
added CONFIG_PAHOLE_VERSION after all. Now several CONFIG options, as
well as the combination of DEBUG_INFO_BTF and DEBUG_INFO_DWARF5, are
guarded by PAHOLE_VERSION.

The remaining compile-time check in scripts/link-vmlinux.sh now appears
to be an awkward inconsistency.

This commit adopts Nathan's original work.

[1]: https://lore.kernel.org/lkml/[email protected]/

Signed-off-by: Masahiro Yamada <[email protected]>
Reviewed-by: Alan Maguire <[email protected]>
Acked-by: Andrii Nakryiko <[email protected]>
Reviewed-by: Nathan Chancellor <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>

show more ...

btf: remove redundant CONFIG_BPF test in scripts/link-vmlinux.sh

CONFIG_DEBUG_INFO_BTF depends on CONFIG_BPF_SYSCALL, which in turn
selects CONFIG_BPF.

When CONFIG_DEBUG_INFO_BTF=y, CONFIG_BPF=y is

btf: remove redundant CONFIG_BPF test in scripts/link-vmlinux.sh

CONFIG_DEBUG_INFO_BTF depends on CONFIG_BPF_SYSCALL, which in turn
selects CONFIG_BPF.

When CONFIG_DEBUG_INFO_BTF=y, CONFIG_BPF=y is always met.

Signed-off-by: Masahiro Yamada <[email protected]>
Reviewed-by: Alan Maguire <[email protected]>
Acked-by: Andrii Nakryiko <[email protected]>
Reviewed-by: Nathan Chancellor <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>

show more ...

kbuild: remove recent dependency on "truncate" program

Remove the recently-added dependency on the truncate program for
building the kernel. truncate is not available when building the kernel
under

kbuild: remove recent dependency on "truncate" program

Remove the recently-added dependency on the truncate program for
building the kernel. truncate is not available when building the kernel
under Yocto. It could be added, but it would be better just to avoid
the unnecessary dependency.

Fixes: 1472464c6248 ("kbuild: avoid scripts/kallsyms parsing /dev/null")
Signed-off-by: Tony Battersby <[email protected]>
Reviewed-by: Nathan Chancellor <[email protected]>
Signed-off-by: Masahiro Yamada <[email protected]>

show more ...

kallsyms: Do not cleanup .llvm.<hash> suffix before sorting symbols

Cleaning up the symbols causes various issues afterwards. Let's sort
the list based on original name.

Signed-off-by: Song Liu <so

kallsyms: Do not cleanup .llvm.<hash> suffix before sorting symbols

Cleaning up the symbols causes various issues afterwards. Let's sort
the list based on original name.

Signed-off-by: Song Liu <[email protected]>
Fixes: 8cc32a9bbf29 ("kallsyms: strip LTO-only suffixes from promoted global functions")
Reviewed-by: Masami Hiramatsu (Google) <[email protected]>
Tested-by: Masami Hiramatsu (Google) <[email protected]>
Acked-by: Petr Mladek <[email protected]>
Reviewed-by: Sami Tolvanen <[email protected]>
Reviewed-by: Luis Chamberlain <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Kees Cook <[email protected]>

show more ...

kbuild: avoid scripts/kallsyms parsing /dev/null

On macOS, as reported by Daniel Gomez, getline() sets ENOTTY to errno
if it is requested to read from /dev/null.

If this is worth fixing, I would ra

kbuild: avoid scripts/kallsyms parsing /dev/null

On macOS, as reported by Daniel Gomez, getline() sets ENOTTY to errno
if it is requested to read from /dev/null.

If this is worth fixing, I would rather pass an empty file to
scripts/kallsyms instead of adding the ugly #ifdef __APPLE__.

Fixes: c442db3f49f2 ("kbuild: remove PROVIDE() for kallsyms symbols")
Reported-by: Daniel Gomez <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Masahiro Yamada <[email protected]>
Reviewed-by: Nicolas Schier <[email protected]>
Reviewed-by: Daniel Gomez <[email protected]>

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kallsyms: get rid of code for absolute kallsyms

Commit cf8e8658100d ("arch: Remove Itanium (IA-64) architecture")
removed the last use of the absolute kallsyms.

Signed-off-by: Jann Horn <jannh@goog

kallsyms: get rid of code for absolute kallsyms

Commit cf8e8658100d ("arch: Remove Itanium (IA-64) architecture")
removed the last use of the absolute kallsyms.

Signed-off-by: Jann Horn <[email protected]>
Acked-by: Arnd Bergmann <[email protected]>
Link: https://lore.kernel.org/all/[email protected]/
[[email protected]: rebase the code and reword the commit description]
Signed-off-by: Masahiro Yamada <[email protected]>

show more ...

kbuild: merge temporary vmlinux for BTF and kallsyms

CONFIG_DEBUG_INFO_BTF=y requires one additional link step.
(.tmp_vmlinux.btf)

CONFIG_KALLSYMS=y requires two additional link steps.
(.tmp_vmlinu

kbuild: merge temporary vmlinux for BTF and kallsyms

CONFIG_DEBUG_INFO_BTF=y requires one additional link step.
(.tmp_vmlinux.btf)

CONFIG_KALLSYMS=y requires two additional link steps.
(.tmp_vmlinux.kallsyms1 and .tmp_vmlinux.kallsyms2)

Enabling both requires three additional link steps.

When CONFIG_DEBUG_INFO_BTF=y and CONFIG_KALLSYMS=y, the current build
process is as follows:

KSYMS .tmp_vmlinux.kallsyms0.S
AS .tmp_vmlinux.kallsyms0.o
LD .tmp_vmlinux.btf # temporary vmlinux for BTF
BTF .btf.vmlinux.bin.o
LD .tmp_vmlinux.kallsyms1 # temporary vmlinux for kallsyms step 1
NM .tmp_vmlinux.kallsyms1.syms
KSYMS .tmp_vmlinux.kallsyms1.S
AS .tmp_vmlinux.kallsyms1.o
LD .tmp_vmlinux.kallsyms2 # temporary vmlinux for kallsyms step 2
NM .tmp_vmlinux.kallsyms2.syms
KSYMS .tmp_vmlinux.kallsyms2.S
AS .tmp_vmlinux.kallsyms2.o
LD vmlinux # final vmlinux

This is redundant because the BTF generation and the kallsyms step 1 can
be performed against the same temporary vmlinux.

When both CONFIG_DEBUG_INFO_BTF and CONFIG_KALLSYMS are enabled, we can
reduce the number of link steps by one.

This commit changes the build process as follows:

KSYMS .tmp_vmlinux0.kallsyms.S
AS .tmp_vmlinux0.kallsyms.o
LD .tmp_vmlinux1 # temporary vmlinux for BTF and kallsyms step 1
BTF .tmp_vmlinux1.btf.o
NM .tmp_vmlinux1.syms
KSYMS .tmp_vmlinux1.kallsyms.S
AS .tmp_vmlinux1.kallsyms.o
LD .tmp_vmlinux2 # temporary vmlinux for kallsyms step 2
NM .tmp_vmlinux2.syms
KSYMS .tmp_vmlinux2.kallsyms.S
AS .tmp_vmlinux2.kallsyms.o
LD vmlinux # final vmlinux

Signed-off-by: Masahiro Yamada <[email protected]>
Acked-by: Andrii Nakryiko <[email protected]>

show more ...

kbuild: remove PROVIDE() for kallsyms symbols

This reimplements commit 951bcae6c5a0 ("kallsyms: Avoid weak references
for kallsyms symbols") because I am not a big fan of PROVIDE().

As an alternati

kbuild: remove PROVIDE() for kallsyms symbols

This reimplements commit 951bcae6c5a0 ("kallsyms: Avoid weak references
for kallsyms symbols") because I am not a big fan of PROVIDE().

As an alternative solution, this commit prepends one more kallsyms step.

KSYMS .tmp_vmlinux.kallsyms0.S # added
AS .tmp_vmlinux.kallsyms0.o # added
LD .tmp_vmlinux.btf
BTF .btf.vmlinux.bin.o
LD .tmp_vmlinux.kallsyms1
NM .tmp_vmlinux.kallsyms1.syms
KSYMS .tmp_vmlinux.kallsyms1.S
AS .tmp_vmlinux.kallsyms1.o
LD .tmp_vmlinux.kallsyms2
NM .tmp_vmlinux.kallsyms2.syms
KSYMS .tmp_vmlinux.kallsyms2.S
AS .tmp_vmlinux.kallsyms2.o
LD vmlinux

Step 0 takes /dev/null as input, and generates .tmp_vmlinux.kallsyms0.o,
which has a valid kallsyms format with the empty symbol list, and can be
linked to vmlinux. Since it is really small, the added compile-time cost
is negligible.

Signed-off-by: Masahiro Yamada <[email protected]>
Acked-by: Ard Biesheuvel <[email protected]>
Reviewed-by: Nicolas Schier <[email protected]>

show more ...

kbuild: refactor variables in scripts/link-vmlinux.sh

Clean up the variables in scripts/link-vmlinux.sh

- Specify the extra objects directly in vmlinux_link()
- Move the AS rule to kallsyms()
-

kbuild: refactor variables in scripts/link-vmlinux.sh

Clean up the variables in scripts/link-vmlinux.sh

- Specify the extra objects directly in vmlinux_link()
- Move the AS rule to kallsyms()
- Set kallsymso and btf_vmlinux_bin_o where they are generated
- Remove unneeded variable, kallsymso_prev
- Introduce the btf_data variable
- Introduce the strip_debug flag instead of checking the output name

No functional change intended.

Signed-off-by: Masahiro Yamada <[email protected]>
Reviewed-by: Nicolas Schier <[email protected]>

show more ...

kbuild: explicitly run mksysmap as sed script from link-vmlinux.sh

In commit b18b047002b7 ("kbuild: change scripts/mksysmap into sed
script"), the mksysmap script was transformed into a sed script,

kbuild: explicitly run mksysmap as sed script from link-vmlinux.sh

In commit b18b047002b7 ("kbuild: change scripts/mksysmap into sed
script"), the mksysmap script was transformed into a sed script,
made directly executable with "#!/bin/sed -f". Apparently, the path to
sed is different on NixOS.

The shebang can't use the env command, otherwise the "sed -f" command
would be treated as a single argument. This can be solved with the -S
flag, but that is a GNU extension. Explicitly use sed instead of relying
on the executable shebang to fix NixOS builds without breaking build
environments using Busybox.

Fixes: b18b047002b7 ("kbuild: change scripts/mksysmap into sed script")
Reported-by: Kent Overstreet <[email protected]>
Signed-off-by: Richard Acayan <[email protected]>
Reviewed-by: Nathan Chancellor <[email protected]>
Tested-by: Dmitry Safonov <[email protected]>
Signed-off-by: Masahiro Yamada <[email protected]>

show more ...

kbuild: remove a stale comment about cleaning in link-vmlinux.sh

Remove the left-over of commit 51eb95e2da41 ("kbuild: Don't remove
link-vmlinux temporary files on exit/signal").

Signed-off-by: Mas

kbuild: remove a stale comment about cleaning in link-vmlinux.sh

Remove the left-over of commit 51eb95e2da41 ("kbuild: Don't remove
link-vmlinux temporary files on exit/signal").

Signed-off-by: Masahiro Yamada <[email protected]>

show more ...

kbuild: fix short log for AS in link-vmlinux.sh

In convention, short logs print the output file, not the input file.

Let's change the suffix for 'AS' since it assembles *.S into *.o.

[Before]

L

kbuild: fix short log for AS in link-vmlinux.sh

In convention, short logs print the output file, not the input file.

Let's change the suffix for 'AS' since it assembles *.S into *.o.

[Before]

LD .tmp_vmlinux.kallsyms1
NM .tmp_vmlinux.kallsyms1.syms
KSYMS .tmp_vmlinux.kallsyms1.S
AS .tmp_vmlinux.kallsyms1.S
LD .tmp_vmlinux.kallsyms2
NM .tmp_vmlinux.kallsyms2.syms
KSYMS .tmp_vmlinux.kallsyms2.S
AS .tmp_vmlinux.kallsyms2.S
LD vmlinux

[After]

LD .tmp_vmlinux.kallsyms1
NM .tmp_vmlinux.kallsyms1.syms
KSYMS .tmp_vmlinux.kallsyms1.S
AS .tmp_vmlinux.kallsyms1.o
LD .tmp_vmlinux.kallsyms2
NM .tmp_vmlinux.kallsyms2.syms
KSYMS .tmp_vmlinux.kallsyms2.S
AS .tmp_vmlinux.kallsyms2.o
LD vmlinux

Signed-off-by: Masahiro Yamada <[email protected]>

show more ...

kbuild: change scripts/mksysmap into sed script

The previous commit removed the subshell execution from scripts/mksysmap,
which is now simple enough to become a sed script.

Signed-off-by: Masahiro

kbuild: change scripts/mksysmap into sed script

The previous commit removed the subshell execution from scripts/mksysmap,
which is now simple enough to become a sed script.

Signed-off-by: Masahiro Yamada <[email protected]>

show more ...

kbuild: avoid unneeded kallsyms step 3

Since commit 951bcae6c5a0 ("kallsyms: Avoid weak references for kallsyms
symbols"), the kallsyms step 3 always occurs.

You can compare the build logs.

[Befor

kbuild: avoid unneeded kallsyms step 3

Since commit 951bcae6c5a0 ("kallsyms: Avoid weak references for kallsyms
symbols"), the kallsyms step 3 always occurs.

You can compare the build logs.

[Before 951bcae6c5a0]

$ git checkout 951bcae6c5a0^
$ make defconfig all
[ snip ]
LD .tmp_vmlinux.kallsyms1
NM .tmp_vmlinux.kallsyms1.syms
KSYMS .tmp_vmlinux.kallsyms1.S
AS .tmp_vmlinux.kallsyms1.S
LD .tmp_vmlinux.kallsyms2
NM .tmp_vmlinux.kallsyms2.syms
KSYMS .tmp_vmlinux.kallsyms2.S
AS .tmp_vmlinux.kallsyms2.S
LD vmlinux

[After 951bcae6c5a0]

$ git checkout 951bcae6c5a0
$ make defconfig all
[ snip ]
LD .tmp_vmlinux.kallsyms1
NM .tmp_vmlinux.kallsyms1.syms
KSYMS .tmp_vmlinux.kallsyms1.S
AS .tmp_vmlinux.kallsyms1.S
LD .tmp_vmlinux.kallsyms2
NM .tmp_vmlinux.kallsyms2.syms
KSYMS .tmp_vmlinux.kallsyms2.S
AS .tmp_vmlinux.kallsyms2.S
LD .tmp_vmlinux.kallsyms3 # should not happen
NM .tmp_vmlinux.kallsyms3.syms # should not happen
KSYMS .tmp_vmlinux.kallsyms3.S # should not happen
AS .tmp_vmlinux.kallsyms3.S # should not happen
LD vmlinux

The resulting vmlinux is correct, but it always requires an additional
linking step.

The symbols produced by kallsyms are excluded from kallsyms itself
because they were previously missing in step 1. With those symbols
excluded, the symbol lists matched between step 1 and step 2,
eliminating the need for step 3. Now, this has a negative effect.

Since 951bcae6c5a0, the PROVIDE() directives provide the fallback
definitions, which are not trimmed from the sysbol list in step 1
because ${kallsymso_prev} is empty at this point.

In step 2, ${kallsymso_prev} is set, and the kallsyms_* symbols are
trimmed from the symbol list.

Due to the table size difference between step 1 and step 2 (the former
is larger due to the presence of kallsyms_*), step 3 is triggered.

Now that the kallsyms_* symbols are always linked, let's stop omitting
them from kallsyms. This avoids unnecessary step 3.

Fixes: 951bcae6c5a0 ("kallsyms: Avoid weak references for kallsyms symbols")
Signed-off-by: Masahiro Yamada <[email protected]>

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kbuild: Fix changing ELF file type for output of gen_btf for big endian

Commit 90ceddcb4950 ("bpf: Support llvm-objcopy for vmlinux BTF")
changed the ELF type of .btf.vmlinux.bin.o to ET_REL via dd,

kbuild: Fix changing ELF file type for output of gen_btf for big endian

Commit 90ceddcb4950 ("bpf: Support llvm-objcopy for vmlinux BTF")
changed the ELF type of .btf.vmlinux.bin.o to ET_REL via dd, which works
fine for little endian platforms:

00000000 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 |.ELF............|
-00000010 03 00 b7 00 01 00 00 00 00 00 00 80 00 80 ff ff |................|
+00000010 01 00 b7 00 01 00 00 00 00 00 00 80 00 80 ff ff |................|

However, for big endian platforms, it changes the wrong byte, resulting
in an invalid ELF file type, which ld.lld rejects:

00000000 7f 45 4c 46 02 02 01 00 00 00 00 00 00 00 00 00 |.ELF............|
-00000010 00 03 00 16 00 00 00 01 00 00 00 00 00 10 00 00 |................|
+00000010 01 03 00 16 00 00 00 01 00 00 00 00 00 10 00 00 |................|

Type: <unknown>: 103

ld.lld: error: .btf.vmlinux.bin.o: unknown file type

Fix this by updating the entire 16-bit e_type field rather than just a
single byte, so that everything works correctly for all platforms and
linkers.

00000000 7f 45 4c 46 02 02 01 00 00 00 00 00 00 00 00 00 |.ELF............|
-00000010 00 03 00 16 00 00 00 01 00 00 00 00 00 10 00 00 |................|
+00000010 00 01 00 16 00 00 00 01 00 00 00 00 00 10 00 00 |................|

Type: REL (Relocatable file)

While in the area, update the comment to mention that binutils 2.35+
matches LLD's behavior of rejecting an ET_EXEC input, which occurred
after the comment was added.

Cc: [email protected]
Fixes: 90ceddcb4950 ("bpf: Support llvm-objcopy for vmlinux BTF")
Link: https://github.com/llvm/llvm-project/pull/75643
Suggested-by: Masahiro Yamada <[email protected]>
Signed-off-by: Nathan Chancellor <[email protected]>
Reviewed-by: Fangrui Song <[email protected]>
Reviewed-by: Nicolas Schier <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Reviewed-by: Justin Stitt <[email protected]>
Signed-off-by: Masahiro Yamada <[email protected]>

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scripts/kallsyms: exclude symbols generated by itself dynamically

Drop the symbols generated by scripts/kallsyms itself automatically
instead of maintaining the symbol list manually.

Pass the kalls

scripts/kallsyms: exclude symbols generated by itself dynamically

Drop the symbols generated by scripts/kallsyms itself automatically
instead of maintaining the symbol list manually.

Pass the kallsyms object from the previous kallsyms step (if it exists)
as the third parameter of scripts/mksysmap, which will weed out the
generated symbols from the input to the next kallsyms step.

Signed-off-by: Masahiro Yamada <[email protected]>

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scripts/link-vmlinux.sh: fix error message presentation

This comes out as

Try make KALLSYMS_EXTRA_PASS=1 as a workaround

but we want quotes:

Try "make KALLSYMS_EXTRA_PASS=1" as a workaround

scripts/link-vmlinux.sh: fix error message presentation

This comes out as

Try make KALLSYMS_EXTRA_PASS=1 as a workaround

but we want quotes:

Try "make KALLSYMS_EXTRA_PASS=1" as a workaround

Link: https://lkml.kernel.org/r/[email protected]
Cc: kernel test robot <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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