From: Ahmad Fatoum <ahmad@a3f.at>
To: barebox@lists.infradead.org
Subject: [PATCH 1/2] kbuild: add '-fno-stack-check' to barebox build options
Date: Tue, 23 Feb 2021 08:24:26 +0100 [thread overview]
Message-ID: <20210223072427.166689-1-ahmad@a3f.at> (raw)
This ports over Linux commit 3ce120b16cc5 ("kbuild: add
'-fno-stack-check' to kernel build options"):
Author: Linus Torvalds <torvalds@linux-foundation.org>
kbuild: add '-fno-stack-check' to kernel build options
It appears that hardened gentoo enables "-fstack-check" by default for
gcc.
That doesn't work _at_all_ for the kernel, because the kernel stack
doesn't act like a user stack at all: it's much smaller, and it doesn't
auto-expand on use. So the extra "probe one page below the stack" code
generated by -fstack-check just breaks the kernel in horrible ways,
causing infinite double faults etc.
[ I have to say, that the particular code gcc generates looks very
stupid even for user space where it works, but that's a separate
issue. ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I am porting it, because it may become more acute with the incoming
support for multiple stacks (via initjmp).
Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
---
Makefile | 3 +++
1 file changed, 3 insertions(+)
diff --git a/Makefile b/Makefile
index f3c85cff9430..fa7fbbeb35f0 100644
--- a/Makefile
+++ b/Makefile
@@ -622,6 +622,9 @@ KBUILD_CFLAGS += $(call cc-option, -fno-delete-null-pointer-checks,)
# disable invalid "can't wrap" optimizations for signed / pointers
KBUILD_CFLAGS += $(call cc-option,-fno-strict-overflow)
+# Make sure -fstack-check isn't enabled (like gentoo apparently did)
+KBUILD_CFLAGS += $(call cc-option,-fno-stack-check)
+
KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
# Align the bit size of userspace programs with the kernel
--
2.30.0
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next reply other threads:[~2021-02-23 7:24 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-23 7:24 Ahmad Fatoum [this message]
2021-02-23 7:24 ` [PATCH 2/2] kbuild: add '-fcf-protection=none' " Ahmad Fatoum
2021-02-24 8:49 ` [PATCH 1/2] kbuild: add '-fno-stack-check' " Sascha Hauer
2021-03-16 19:10 ` Ahmad Fatoum
2021-03-22 5:12 ` Sascha Hauer
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