From: Alexandre Ghiti <alex@ghiti.fr>
To: Michael Ellerman <mpe@ellerman.id.au>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Anup Patel <Anup.Patel@wdc.com>,
Atish Patra <Atish.Patra@wdc.com>, Zong Li <zong.li@sifive.com>,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-riscv@lists.infradead.org
Cc: Alexandre Ghiti <alex@ghiti.fr>
Subject: [PATCH v3 3/3] arch, scripts: Add script to check relocations at compile time
Date: Sun, 24 May 2020 04:52:59 -0400 [thread overview]
Message-ID: <20200524085259.24784-4-alex@ghiti.fr> (raw)
In-Reply-To: <20200524085259.24784-1-alex@ghiti.fr>
Relocating kernel at runtime is done very early in the boot process, so
it is not convenient to check for relocations there and react in case a
relocation was not expected.
Powerpc architecture has a script that allows to check at compile time
for such unexpected relocations: extract the common logic to scripts/
and add arch specific scripts triggered at postlink.
At the moment, powerpc and riscv architectures take advantage of this
compile-time check.
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
arch/powerpc/tools/relocs_check.sh | 18 ++-------------
arch/riscv/Makefile.postlink | 36 ++++++++++++++++++++++++++++++
arch/riscv/tools/relocs_check.sh | 26 +++++++++++++++++++++
scripts/relocs_check.sh | 20 +++++++++++++++++
4 files changed, 84 insertions(+), 16 deletions(-)
create mode 100644 arch/riscv/Makefile.postlink
create mode 100755 arch/riscv/tools/relocs_check.sh
create mode 100755 scripts/relocs_check.sh
diff --git a/arch/powerpc/tools/relocs_check.sh b/arch/powerpc/tools/relocs_check.sh
index 014e00e74d2b..e367895941ae 100755
--- a/arch/powerpc/tools/relocs_check.sh
+++ b/arch/powerpc/tools/relocs_check.sh
@@ -15,21 +15,8 @@ if [ $# -lt 3 ]; then
exit 1
fi
-# Have Kbuild supply the path to objdump and nm so we handle cross compilation.
-objdump="$1"
-nm="$2"
-vmlinux="$3"
-
-# Remove from the bad relocations those that match an undefined weak symbol
-# which will result in an absolute relocation to 0.
-# Weak unresolved symbols are of that form in nm output:
-# " w _binary__btf_vmlinux_bin_end"
-undef_weak_symbols=$($nm "$vmlinux" | awk '$1 ~ /w/ { print $2 }')
-
bad_relocs=$(
-$objdump -R "$vmlinux" |
- # Only look at relocation lines.
- grep -E '\<R_' |
+${srctree}/scripts/relocs_check.sh "$@" |
# These relocations are okay
# On PPC64:
# R_PPC64_RELATIVE, R_PPC64_NONE
@@ -43,8 +30,7 @@ R_PPC_ADDR16_LO
R_PPC_ADDR16_HI
R_PPC_ADDR16_HA
R_PPC_RELATIVE
-R_PPC_NONE' |
- ([ "$undef_weak_symbols" ] && grep -F -w -v "$undef_weak_symbols" || cat)
+R_PPC_NONE'
)
if [ -z "$bad_relocs" ]; then
diff --git a/arch/riscv/Makefile.postlink b/arch/riscv/Makefile.postlink
new file mode 100644
index 000000000000..bf2b2bca1845
--- /dev/null
+++ b/arch/riscv/Makefile.postlink
@@ -0,0 +1,36 @@
+# SPDX-License-Identifier: GPL-2.0
+# ===========================================================================
+# Post-link riscv pass
+# ===========================================================================
+#
+# Check that vmlinux relocations look sane
+
+PHONY := __archpost
+__archpost:
+
+-include include/config/auto.conf
+include scripts/Kbuild.include
+
+quiet_cmd_relocs_check = CHKREL $@
+cmd_relocs_check = \
+ $(CONFIG_SHELL) $(srctree)/arch/riscv/tools/relocs_check.sh "$(OBJDUMP)" "$(NM)" "$@"
+
+# `@true` prevents complaint when there is nothing to be done
+
+vmlinux: FORCE
+ @true
+ifdef CONFIG_RELOCATABLE
+ $(call if_changed,relocs_check)
+endif
+
+%.ko: FORCE
+ @true
+
+clean:
+ @true
+
+PHONY += FORCE clean
+
+FORCE:
+
+.PHONY: $(PHONY)
diff --git a/arch/riscv/tools/relocs_check.sh b/arch/riscv/tools/relocs_check.sh
new file mode 100755
index 000000000000..baeb2e7b2290
--- /dev/null
+++ b/arch/riscv/tools/relocs_check.sh
@@ -0,0 +1,26 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Based on powerpc relocs_check.sh
+
+# This script checks the relocations of a vmlinux for "suspicious"
+# relocations.
+
+if [ $# -lt 3 ]; then
+ echo "$0 [path to objdump] [path to nm] [path to vmlinux]" 1>&2
+ exit 1
+fi
+
+bad_relocs=$(
+${srctree}/scripts/relocs_check.sh "$@" |
+ # These relocations are okay
+ # R_RISCV_RELATIVE
+ grep -F -w -v 'R_RISCV_RELATIVE'
+)
+
+if [ -z "$bad_relocs" ]; then
+ exit 0
+fi
+
+num_bad=$(echo "$bad_relocs" | wc -l)
+echo "WARNING: $num_bad bad relocations"
+echo "$bad_relocs"
diff --git a/scripts/relocs_check.sh b/scripts/relocs_check.sh
new file mode 100755
index 000000000000..137c660499f3
--- /dev/null
+++ b/scripts/relocs_check.sh
@@ -0,0 +1,20 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+# Get a list of all the relocations, remove from it the relocations
+# that are known to be legitimate and return this list to arch specific
+# script that will look for suspicious relocations.
+
+objdump="$1"
+nm="$2"
+vmlinux="$3"
+
+# Remove from the possible bad relocations those that match an undefined
+# weak symbol which will result in an absolute relocation to 0.
+# Weak unresolved symbols are of that form in nm output:
+# " w _binary__btf_vmlinux_bin_end"
+undef_weak_symbols=$($nm "$vmlinux" | awk '$1 ~ /w/ { print $2 }')
+
+$objdump -R "$vmlinux" |
+ grep -E '\<R_' |
+ ([ "$undef_weak_symbols" ] && grep -F -w -v "$undef_weak_symbols" || cat)
--
2.20.1
next prev parent reply other threads:[~2020-05-24 8:56 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-24 8:52 [PATCH v3 0/3] vmalloc kernel mapping and relocatable kernel Alexandre Ghiti
2020-05-24 8:52 ` [PATCH v3 1/3] riscv: Move kernel mapping to vmalloc zone Alexandre Ghiti
2020-05-26 9:43 ` Zong Li
2020-05-26 17:06 ` Alex Ghiti
2020-05-27 6:05 ` Zong Li
2020-05-27 7:29 ` Alex Ghiti
2020-05-28 13:07 ` Alex Ghiti
2020-05-27 7:33 ` kbuild test robot
2020-05-24 8:52 ` [PATCH v3 2/3] riscv: Introduce CONFIG_RELOCATABLE Alexandre Ghiti
2020-05-26 9:05 ` Zong Li
2020-05-29 12:04 ` Anup Patel
2020-05-24 8:52 ` Alexandre Ghiti [this message]
2020-05-29 12:08 ` [PATCH v3 3/3] arch, scripts: Add script to check relocations at compile time Anup Patel
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