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FROMLIST: BACKPORT: kbuild: fix dynamic ftrace with clang LTO

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With CONFIG_LTO_CLANG enabled, LLVM IR won't be compiled into object
files until modpost_link. This change postpones calls to recordmcount
until after this step.

In order to exclude ftrace_process_locs from inspection, we add a new
code section .text..ftrace, which we tell recordmcount to ignore, and
a __norecordmcount attribute for moving functions to this section.

Bug: 62093296
Bug: 67506682
Change-Id: Iba2c053968206acf533fadab1eb34a743b5088ee
(am from https://patchwork.kernel.org/patch/10060327/)
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
This commit is contained in:
Sami Tolvanen 2017-06-16 12:52:57 -07:00
parent 475bdd7d35
commit 7bd125e57b
9 changed files with 52 additions and 7 deletions
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16
scripts/link-vmlinux.sh
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@ -113,6 +113,19 @@ modpost_link()
${LD} ${LDFLAGS} -r -o ${1} $(modversions) ${objects}
}
# If CONFIG_LTO_CLANG is selected, we postpone running recordmcount until
# we have compiled LLVM IR to an object file.
recordmcount()
{
if [ -z "${CONFIG_LTO_CLANG}" ]; then
return
fi
if [ -n "${CONFIG_FTRACE_MCOUNT_RECORD}" ]; then
scripts/recordmcount ${RECORDMCOUNT_FLAGS} $*
fi
}
# Link of vmlinux
# ${1} - optional extra .o files
# ${2} - output file
@ -282,6 +295,9 @@ if [ -n "${CONFIG_LTO_CLANG}" ]; then
# vmlinux_link
KBUILD_VMLINUX_INIT=
KBUILD_VMLINUX_MAIN=vmlinux.o
# Call recordmcount if needed
recordmcount vmlinux.o
fi
kallsymso=""