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linux-google-crosshatch-mainline: revert: build with LLVM and sync kconfig

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Reverts commit b33ba8203c

Build failing in bpo.

Signed-off-by: Aster Boese <asterboese@mailbox.org>
Part-of: <https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/8299>
This commit is contained in:
Aster Boese 2026-04-07 20:05:32 +02:00 • committed by The Friendly Meow (merge) Bot
parent 2d7c216e36
commit 130e3e9e89
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2 changed files with 5 additions and 142 deletions
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123
device/testing/linux-google-crosshatch-mainline/10_add_stpcpy.patch
View file

@ -1,123 +0,0 @@
From 5934637641c863cc2c1765a0d01c5b6f53ecc4fc Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers@google.com>
Date: Wed, 26 Aug 2020 15:21:29 +1000
Subject: lib/string.c: implement stpcpy
LLVM implemented a recent "libcall optimization" that lowers calls to
`sprintf(dest, "%s", str)` where the return value is used to `stpcpy(dest,
str) - dest`. This generally avoids the machinery involved in parsing
format strings. `stpcpy` is just like `strcpy` except it returns the
pointer to the new tail of `dest`. This optimization was introduced into
clang-12.
Implement this so that we don't observe linkage failures due to missing
symbol definitions for `stpcpy`.
Similar to last year's fire drill with: commit 5f074f3e192f
("lib/string.c: implement a basic bcmp")
The kernel is somewhere between a "freestanding" environment (no full
libc) and "hosted" environment (many symbols from libc exist with the same
type, function signature, and semantics).
As H. Peter Anvin notes, there's not really a great way to inform the
compiler that you're targeting a freestanding environment but would like
to opt-in to some libcall optimizations (see pr/47280 below), rather than
opt-out.
Arvind notes, -fno-builtin-* behaves slightly differently between GCC and
Clang, and Clang is missing many __builtin_* definitions, which I consider
a bug in Clang and am working on fixing.
Masahiro summarizes the subtle distinction between compilers justly:
To prevent transformation from foo() into bar(), there are two ways in
Clang to do that; -fno-builtin-foo, and -fno-builtin-bar. There is
only one in GCC; -fno-buitin-foo.
(Any difference in that behavior in Clang is likely a bug from a missing
__builtin_* definition.)
Masahiro also notes:
We want to disable optimization from foo() to bar(),
but we may still benefit from the optimization from
foo() into something else. If GCC implements the same transform, we
would run into a problem because it is not -fno-builtin-bar, but
-fno-builtin-foo that disables that optimization.
In this regard, -fno-builtin-foo would be more future-proof than
-fno-built-bar, but -fno-builtin-foo is still potentially overkill. We
may want to prevent calls from foo() being optimized into calls to
bar(), but we still may want other optimization on calls to foo().
It seems that compilers today don't quite provide the fine grain control
over which libcall optimizations pseudo-freestanding environments would
prefer.
Finally, Kees notes that this interface is unsafe, so we should not
encourage its use. As such, I've removed the declaration from any header,
but it still needs to be exported to avoid linkage errors in modules.
Link: https://lkml.kernel.org/r/20200825140001.2941001-1-ndesaulniers@google.com
Link: https://bugs.llvm.org/show_bug.cgi?id=47162
Link: https://bugs.llvm.org/show_bug.cgi?id=47280
Link: https://github.com/ClangBuiltLinux/linux/issues/1126
Link: https://man7.org/linux/man-pages/man3/stpcpy.3.html
Link: https://pubs.opengroup.org/onlinepubs/9699919799/functions/stpcpy.html
Link: https://reviews.llvm.org/D85963
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reported-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Suggested-by: Andy Lavr <andy.lavr@gmail.com>
Suggested-by: Arvind Sankar <nivedita@alum.mit.edu>
Suggested-by: Joe Perches <joe@perches.com>
Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: <stable@vger.kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Alexandru Ardelean <alexandru.ardelean@analog.com>
Cc: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
---
lib/string.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/lib/string.c b/lib/string.c
index 6012c385fb314d..6bd0cf0fb009a2 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -272,6 +272,30 @@ ssize_t strscpy_pad(char *dest, const char *src, size_t count)
}
EXPORT_SYMBOL(strscpy_pad);
+/**
+ * stpcpy - copy a string from src to dest returning a pointer to the new end
+ * of dest, including src's %NUL-terminator. May overrun dest.
+ * @dest: pointer to end of string being copied into. Must be large enough
+ * to receive copy.
+ * @src: pointer to the beginning of string being copied from. Must not overlap
+ * dest.
+ *
+ * stpcpy differs from strcpy in a key way: the return value is the new
+ * %NUL-terminated character. (for strcpy, the return value is a pointer to
+ * src. This interface is considered unsafe as it doesn't perform bounds
+ * checking of the inputs. As such it's not recommended for usage. Instead,
+ * its definition is provided in case the compiler lowers other libcalls to
+ * stpcpy.
+ */
+char *stpcpy(char *__restrict__ dest, const char *__restrict__ src);
+char *stpcpy(char *__restrict__ dest, const char *__restrict__ src)
+{
+ while ((*dest++ = *src++) != '\0')
+ /* nothing */;
+ return --dest;
+}
+EXPORT_SYMBOL(stpcpy);
+
#ifndef __HAVE_ARCH_STRCAT
/**
* strcat - Append one %NUL-terminated string to another
--
cgit 1.2.3-korg

24
device/testing/linux-google-crosshatch-mainline/APKBUILD
View file

@ -8,24 +8,13 @@ _config="config-$_flavor.$CARCH"
maintainer=""
pkgname=linux-$_flavor
pkgver=5.3_rc5
pkgrel=9
pkgrel=10
arch="aarch64"
_carch="arm64"
pkgdesc="Google Pixel 3 XL kernel fork, close to mainline"
url="https://kernel.org/"
license="GPL-2.0-only"
makedepends="
bison
clang
findutils
flex
lld
llvm
openssl-dev
perl
postmarketos-installkernel
zstd
"
license="GPL2-2.0-only"
makedepends="perl sed installkernel bash gmp-dev bc linux-headers elfutils-dev openssl-dev file bison flex"
options="!strip !check !tracedeps
pmb:cross-native
"
@ -37,7 +26,6 @@ source="
$pkgname-$_commit.tar.gz::https://github.com/Pixel3Dev/$_repository/archive/$_commit.tar.gz
config-$_flavor.aarch64
0001-linux4.17-gcc10-extern_YYLOC_global_declaration.patch
10_add_stpcpy.patch
"
builddir="$srcdir/linux-$_commit"
@ -50,7 +38,7 @@ prepare() {
build() {
unset LDFLAGS
# V=1: workaround for pma#1990
make ARCH="$_carch" LLVM=1 LLVM_IAS=1 \
make ARCH="$_carch" CC="${CC:-gcc}" \
KBUILD_BUILD_VERSION="$((pkgrel + 1 ))-$_flavor" \
CFLAGS_MODULE=-fno-pic V=1
}
@ -62,8 +50,6 @@ package() {
make modules_install dtbs_install \
ARCH="$_carch" \
LLVM=1 \
LLVM_IAS=1 \
INSTALL_PATH="$pkgdir"/boot \
INSTALL_MOD_PATH="$pkgdir" \
INSTALL_DTBS_PATH="$pkgdir/boot/dtbs"
@ -74,9 +60,9 @@ package() {
"$pkgdir/usr/share/kernel/$_flavor/kernel.release"
}
sha512sums="
1ce235689d7ce0b40be203cb16c1bdfe9bc7b2c5e793a942afc5ea4f3268a0a15b684d9c4017a87916d989d8592a96a4223976c95bf7fcca603e71d2f20fee86 linux-google-crosshatch-mainline-9c9b87cec239101274451cc9c086da60108f9fda.tar.gz
858f75f29fc18b600f2a8359c69d53628665f926fa3b06010a9cb6b377555e4786b2967c98a9a752277dae1071bfb1980f6422e1d72f4661da4b652a342004f6 config-google-crosshatch-mainline.aarch64
27827877040007fc1c4c719f7e2e19e5c272d44972415cfc53feba0313d87e4074f8204bdb13cbc5fe21ea61bf595314b68f10c081e7b7bac3c888b60f008acf 0001-linux4.17-gcc10-extern_YYLOC_global_declaration.patch
706c2d3a178231d9f79f5f594cebaafdc6a39add602cca4c8a381ca181d27a82afb49aef494dc7b11905089d337c344cb9ce05b6d94199af37a4a46cc9cf22f1 10_add_stpcpy.patch
"