linux/arch/um
Nathan Chancellor 846cfbeed0 um: Fix adding '-no-pie' for clang
The kernel builds with -fno-PIE, so commit 883354afbc ("um: link
vmlinux with -no-pie") added the compiler linker flag '-no-pie' via
cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer.

While this works for GCC, this does not work for clang because cc-option
uses '-c', which stops the pipeline right before linking, so '-no-pie'
is unconsumed and clang warns, causing cc-option to fail just as it
would if the option was entirely unsupported:

  $ clang -Werror -no-pie -c -o /dev/null -x c /dev/null
  clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument]

A recent version of clang exposes this because it generates a relocation
under '-mcmodel=large' that is not supported in PIE mode:

  /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE
  /usr/sbin/ld: failed to set dynamic section sizes: bad value
  clang: error: linker command failed with exit code 1 (use -v to see invocation)

Remove the cc-option check altogether. It is wasteful to invoke the
compiler to check for '-no-pie' because only one supported compiler
version does not support it, GCC 5.x (as it is supported with the
minimum version of clang and GCC 6.1.0+). Use a combination of the
gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add
'-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all
compilers that support this. Furthermore, using gcc-min-version can help
turn this back into

  LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie

when the minimum version of GCC is bumped past 6.1.0.

Cc: stable@vger.kernel.org
Closes: https://github.com/ClangBuiltLinux/linux/issues/1982
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2024-01-28 01:13:37 +09:00
..
configs um: Fix hostaudio build errors 2023-08-19 23:30:22 +02:00
drivers TTY/Serial changes for 6.8-rc1 2024-01-18 11:37:24 -08:00
include um: Remove unused register save/restore functions 2024-01-05 16:28:57 +01:00
kernel This pull request contains the following changes for UML: 2024-01-17 10:44:34 -08:00
os-Linux um: Remove unused register save/restore functions 2024-01-05 16:28:57 +01:00
scripts um: prevent user code in modules 2023-04-20 23:06:38 +02:00
.gitignore um: gitignore: Add kernel/capflags.c 2021-12-21 21:22:43 +01:00
Kbuild um: use obj-y to descend into arch/um/*/ 2023-08-26 22:41:34 +02:00
Kconfig Landlock updates for v6.5-rc1 2023-06-27 17:10:27 -07:00
Kconfig.debug um: Disable CONFIG_GCOV with MODULES 2021-04-15 23:10:33 +02:00
Makefile um: Fix adding '-no-pie' for clang 2024-01-28 01:13:37 +09:00
Makefile-os-Linux
Makefile-skas arch: um: Add Clang coverage support 2024-01-05 00:30:35 +01:00