From: Hans de Goede <hdegoede@redhat.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H . Peter Anvin" <hpa@zytor.com>
Cc: Hans de Goede <hdegoede@redhat.com>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v5 2/2] x86/purgatory: Make sure we fail the build if purgatory.ro has missing symbols
Date: Thu, 12 Mar 2020 12:49:51 +0100 [thread overview]
Message-ID: <20200312114951.56009-2-hdegoede@redhat.com> (raw)
In-Reply-To: <20200312114951.56009-1-hdegoede@redhat.com>
Since we link purgatory.ro with -r aka we enable "incremental linking"
no checks for unresolved symbols is done while linking purgatory.ro.
Changes to the sha256 code has caused the purgatory in 5.4-rc1 to have
a missing symbol on memzero_explicit, yet things still happily build.
This commit adds an extra check for unresolved symbols by calling ld
without -r before running bin2c to generate kexec-purgatory.c.
This causes a build of 5.4-rc1 with this patch added to fail as it should:
CHK arch/x86/purgatory/purgatory.ro
ld: arch/x86/purgatory/purgatory.ro: in function `sha256_transform':
sha256.c:(.text+0x1c0c): undefined reference to `memzero_explicit'
make[2]: *** [arch/x86/purgatory/Makefile:72:
arch/x86/purgatory/kexec-purgatory.c] Error 1
make[1]: *** [scripts/Makefile.build:509: arch/x86/purgatory] Error 2
make: *** [Makefile:1650: arch/x86] Error 2
This will help us catch missing symbols in the purgatory sooner.
Note this commit also removes --no-undefined from LDFLAGS_purgatory.ro
as that has no effect.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v3:
- Add a .gitignore file with purgatory.chk listed in it
Changes in v2:
- Using 2 if_changed lines under a single rule does not work, then
1 of the 2 will always execute each build.
Instead add a new (unused) purgatory.chk intermediate which gets
linked from purgatory.ro without -r to do the missing symbols check
- This also fixes the check generating an a.out file (oops)
---
arch/x86/purgatory/.gitignore | 1 +
arch/x86/purgatory/Makefile | 13 ++++++++++---
2 files changed, 11 insertions(+), 3 deletions(-)
create mode 100644 arch/x86/purgatory/.gitignore
diff --git a/arch/x86/purgatory/.gitignore b/arch/x86/purgatory/.gitignore
new file mode 100644
index 000000000000..d2be1500671d
--- /dev/null
+++ b/arch/x86/purgatory/.gitignore
@@ -0,0 +1 @@
+purgatory.chk
diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index 4a35b9b94cb5..85221cb71c72 100644
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -14,8 +14,12 @@ $(obj)/sha256.o: $(srctree)/lib/crypto/sha256.c FORCE
CFLAGS_sha256.o := -D__DISABLE_EXPORTS
-LDFLAGS_purgatory.ro := -e purgatory_start -r --no-undefined -nostdlib -z nodefaultlib
-targets += purgatory.ro
+# Since we link purgatory.ro with -r unresolved symbols are not checked, so we
+# also link a purgatory.chk binary without -r to check for unresolved symbols.
+PURGATORY_LDFLAGS := -e purgatory_start -nostdlib -z nodefaultlib
+LDFLAGS_purgatory.ro := -r $(PURGATORY_LDFLAGS)
+LDFLAGS_purgatory.chk := $(PURGATORY_LDFLAGS)
+targets += purgatory.ro purgatory.chk
GCOV_PROFILE := n
KASAN_SANITIZE := n
@@ -60,12 +64,15 @@ CFLAGS_string.o += $(PURGATORY_CFLAGS)
$(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
$(call if_changed,ld)
+$(obj)/purgatory.chk: $(obj)/purgatory.ro FORCE
+ $(call if_changed,ld)
+
targets += kexec-purgatory.c
quiet_cmd_bin2c = BIN2C $@
cmd_bin2c = $(objtree)/scripts/bin2c kexec_purgatory < $< > $@
-$(obj)/kexec-purgatory.c: $(obj)/purgatory.ro FORCE
+$(obj)/kexec-purgatory.c: $(obj)/purgatory.ro $(obj)/purgatory.chk FORCE
$(call if_changed,bin2c)
obj-$(CONFIG_KEXEC_FILE) += kexec-purgatory.o
--
2.25.1
next prev parent reply other threads:[~2020-03-12 11:50 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-12 11:49 [PATCH v5 1/2] x86/purgatory: Disable various profiling and sanitizing options Hans de Goede
2020-03-12 11:49 ` Hans de Goede [this message]
2020-03-13 18:28 ` Borislav Petkov
2020-03-17 13:08 ` Hans de Goede
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