From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andriin@fb.com>, Sasha Levin <sashal@kernel.org>,
linux-kbuild@vger.kernel.org, netdev@vger.kernel.org,
bpf@vger.kernel.org
Subject: [PATCH AUTOSEL 5.6 168/606] kbuild: Remove debug info from kallsyms linking
Date: Mon, 8 Jun 2020 19:04:53 -0400 [thread overview]
Message-ID: <20200608231211.3363633-168-sashal@kernel.org> (raw)
In-Reply-To: <20200608231211.3363633-1-sashal@kernel.org>
From: Kees Cook <keescook@chromium.org>
[ Upstream commit af73d78bd384aa9b8789aa6e7ddbb165f971276f ]
When CONFIG_DEBUG_INFO is enabled, the two kallsyms linking steps spend
time collecting and writing the dwarf sections to the temporary output
files. kallsyms does not need this information, and leaving it off
halves their linking time. This is especially noticeable without
CONFIG_DEBUG_INFO_REDUCED. The BTF linking stage, however, does still
need those details.
Refactor the BTF and kallsyms generation stages slightly for more
regularized temporary names. Skip debug during kallsyms links.
Additionally move "info BTF" to the correct place since commit
8959e39272d6 ("kbuild: Parameterize kallsyms generation and correct
reporting"), which added "info LD ..." to vmlinux_link calls.
For a full debug info build with BTF, my link time goes from 1m06s to
0m54s, saving about 12 seconds, or 18%.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/202003031814.4AEA3351@keescook
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
scripts/link-vmlinux.sh | 28 +++++++++++++++++++---------
1 file changed, 19 insertions(+), 9 deletions(-)
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index dd484e92752e..ac569e197bfa 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -63,12 +63,18 @@ vmlinux_link()
local lds="${objtree}/${KBUILD_LDS}"
local output=${1}
local objects
+ local strip_debug
info LD ${output}
# skip output file argument
shift
+ # The kallsyms linking does not need debug symbols included.
+ if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
+ strip_debug=-Wl,--strip-debug
+ fi
+
if [ "${SRCARCH}" != "um" ]; then
objects="--whole-archive \
${KBUILD_VMLINUX_OBJS} \
@@ -79,6 +85,7 @@ vmlinux_link()
${@}"
${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \
+ ${strip_debug#-Wl,} \
-o ${output} \
-T ${lds} ${objects}
else
@@ -91,6 +98,7 @@ vmlinux_link()
${@}"
${CC} ${CFLAGS_vmlinux} \
+ ${strip_debug} \
-o ${output} \
-Wl,-T,${lds} \
${objects} \
@@ -106,6 +114,8 @@ gen_btf()
{
local pahole_ver
local bin_arch
+ local bin_format
+ local bin_file
if ! [ -x "$(command -v ${PAHOLE})" ]; then
echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
@@ -118,8 +128,9 @@ gen_btf()
return 1
fi
- info "BTF" ${2}
vmlinux_link ${1}
+
+ info "BTF" ${2}
LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1}
# dump .BTF section into raw binary file to link with final vmlinux
@@ -127,11 +138,12 @@ gen_btf()
cut -d, -f1 | cut -d' ' -f2)
bin_format=$(LANG=C ${OBJDUMP} -f ${1} | grep 'file format' | \
awk '{print $4}')
+ bin_file=.btf.vmlinux.bin
${OBJCOPY} --change-section-address .BTF=0 \
--set-section-flags .BTF=alloc -O binary \
- --only-section=.BTF ${1} .btf.vmlinux.bin
+ --only-section=.BTF ${1} $bin_file
${OBJCOPY} -I binary -O ${bin_format} -B ${bin_arch} \
- --rename-section .data=.BTF .btf.vmlinux.bin ${2}
+ --rename-section .data=.BTF $bin_file ${2}
}
# Create ${2} .o file with all symbols from the ${1} object file
@@ -166,8 +178,8 @@ kallsyms()
kallsyms_step()
{
kallsymso_prev=${kallsymso}
- kallsymso=.tmp_kallsyms${1}.o
- kallsyms_vmlinux=.tmp_vmlinux${1}
+ kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
+ kallsymso=${kallsyms_vmlinux}.o
vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
kallsyms ${kallsyms_vmlinux} ${kallsymso}
@@ -190,7 +202,6 @@ cleanup()
{
rm -f .btf.*
rm -f .tmp_System.map
- rm -f .tmp_kallsyms*
rm -f .tmp_vmlinux*
rm -f System.map
rm -f vmlinux
@@ -257,9 +268,8 @@ tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
btf_vmlinux_bin_o=""
if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
- if gen_btf .tmp_vmlinux.btf .btf.vmlinux.bin.o ; then
- btf_vmlinux_bin_o=.btf.vmlinux.bin.o
- else
+ btf_vmlinux_bin_o=.btf.vmlinux.bin.o
+ if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
echo >&2 "Failed to generate BTF for vmlinux"
echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
exit 1
--
2.25.1
next prev parent reply other threads:[~2020-06-09 0:31 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200608231211.3363633-1-sashal@kernel.org>
2020-06-08 23:02 ` [PATCH AUTOSEL 5.6 006/606] bpf: Fix bug in mmap() implementation for BPF array map Sasha Levin
2020-06-08 23:03 ` [PATCH AUTOSEL 5.6 068/606] bpf: Fix sk_psock refcnt leak when receiving message Sasha Levin
2020-06-08 23:03 ` [PATCH AUTOSEL 5.6 075/606] bpf: Enforce returning 0 for fentry/fexit progs Sasha Levin
2020-06-08 23:03 ` [PATCH AUTOSEL 5.6 076/606] selftests/bpf: Enforce returning 0 for fentry/fexit programs Sasha Levin
2020-06-08 23:03 ` [PATCH AUTOSEL 5.6 077/606] bpf: Restrict bpf_trace_printk()'s %s usage and add %pks, %pus specifier Sasha Levin
2020-06-08 23:03 ` [PATCH AUTOSEL 5.6 114/606] net/ena: Fix build warning in ena_xdp_set() Sasha Levin
2020-06-08 23:04 ` [PATCH AUTOSEL 5.6 141/606] bpf: Restrict bpf_probe_read{, str}() only to archs where they work Sasha Levin
2020-06-08 23:04 ` [PATCH AUTOSEL 5.6 142/606] bpf: Add bpf_probe_read_{user, kernel}_str() to do_refine_retval_range Sasha Levin
2020-06-08 23:04 ` Sasha Levin [this message]
2020-06-08 23:05 ` [PATCH AUTOSEL 5.6 198/606] flow_dissector: Drop BPF flow dissector prog ref on netns cleanup Sasha Levin
2020-06-08 23:05 ` [PATCH AUTOSEL 5.6 202/606] bpf: Prevent mmap()'ing read-only maps as writable Sasha Levin
2020-06-08 23:06 ` [PATCH AUTOSEL 5.6 243/606] net/tls: fix encryption error checking Sasha Levin
2020-06-08 23:06 ` [PATCH AUTOSEL 5.6 287/606] samples: bpf: Fix build error Sasha Levin
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