[ 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.htmlhttps://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&id=7876320f88802b22d4e2daf7eb027dd14175a0f8#n1256
This third version of the patch implements a suggestion from Masahiro
Yamada <yamada.masahiro@socionext.com> to restructure the code as an
additional pattern matching step inside secref_whitelist(), and
further improves the patch description.
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit f880eea68fe593342fa6e09be9bb661f3c297aec upstream.
Use specific prototype instead of an opaque pointer so that the
compiler can catch function prototype mismatch.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit ec91e78d378cc5d4b43805a1227d8e04e5dfa17d upstream.
Commit e49ce14150c6 ("modpost: use linker section to generate table.")
was not so cool as we had expected first; it ended up with ugly section
hacks when commit dd2a3acaecd7 ("mod/file2alias: make modpost compile
on darwin again") came in.
Given a certain degree of unknowledge about the link stage of host
programs, I really want to see simple, stupid table lookup so that
this works in the same way regardless of the underlying executable
format.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Mathieu Malaterre <malat@debian.org>
[nc: Omit rpmsg, sdw, fslmc, tbsvc, and typec as they don't exist here
Add of to avoid backporting two larger patches]
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
