5.15-stable patches

added patches:
	kbuild-remove-support-for-clang-s-thinlto-caching.patch

diff --git a/queue-5.15/kbuild-remove-support-for-clang-s-thinlto-caching.patch b/queue-5.15/kbuild-remove-support-for-clang-s-thinlto-caching.patch
new file mode 100644 (file)
index 0000000..14639fc
--- /dev/null
+++ b/queue-5.15/kbuild-remove-support-for-clang-s-thinlto-caching.patch
@@ -0,0 +1,136 @@
+From aba091547ef6159d52471f42a3ef531b7b660ed8 Mon Sep 17 00:00:00 2001
+From: Nathan Chancellor <nathan@kernel.org>
+Date: Wed, 1 May 2024 15:55:25 -0700
+Subject: kbuild: Remove support for Clang's ThinLTO caching
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+From: Nathan Chancellor <nathan@kernel.org>
+
+commit aba091547ef6159d52471f42a3ef531b7b660ed8 upstream.
+
+There is an issue in clang's ThinLTO caching (enabled for the kernel via
+'--thinlto-cache-dir') with .incbin, which the kernel occasionally uses
+to include data within the kernel, such as the .config file for
+/proc/config.gz. For example, when changing the .config and rebuilding
+vmlinux, the copy of .config in vmlinux does not match the copy of
+.config in the build folder:
+
+  $ echo 'CONFIG_LTO_NONE=n
+  CONFIG_LTO_CLANG_THIN=y
+  CONFIG_IKCONFIG=y
+  CONFIG_HEADERS_INSTALL=y' >kernel/configs/repro.config
+
+  $ make -skj"$(nproc)" ARCH=x86_64 LLVM=1 clean defconfig repro.config vmlinux
+  ...
+
+  $ grep CONFIG_HEADERS_INSTALL .config
+  CONFIG_HEADERS_INSTALL=y
+
+  $ scripts/extract-ikconfig vmlinux | grep CONFIG_HEADERS_INSTALL
+  CONFIG_HEADERS_INSTALL=y
+
+  $ scripts/config -d HEADERS_INSTALL
+
+  $ make -kj"$(nproc)" ARCH=x86_64 LLVM=1 vmlinux
+  ...
+    UPD     kernel/config_data
+    GZIP    kernel/config_data.gz
+    CC      kernel/configs.o
+  ...
+    LD      vmlinux
+  ...
+
+  $ grep CONFIG_HEADERS_INSTALL .config
+  # CONFIG_HEADERS_INSTALL is not set
+
+  $ scripts/extract-ikconfig vmlinux | grep CONFIG_HEADERS_INSTALL
+  CONFIG_HEADERS_INSTALL=y
+
+Without '--thinlto-cache-dir' or when using full LTO, this issue does
+not occur.
+
+Benchmarking incremental builds on a few different machines with and
+without the cache shows a 20% increase in incremental build time without
+the cache when measured by touching init/main.c and running 'make all'.
+
+ARCH=arm64 defconfig + CONFIG_LTO_CLANG_THIN=y on an arm64 host:
+
+  Benchmark 1: With ThinLTO cache
+    Time (mean ± σ):     56.347 s ±  0.163 s    [User: 83.768 s, System: 24.661 s]
+    Range (min … max):   56.109 s … 56.594 s    10 runs
+
+  Benchmark 2: Without ThinLTO cache
+    Time (mean ± σ):     67.740 s ±  0.479 s    [User: 718.458 s, System: 31.797 s]
+    Range (min … max):   67.059 s … 68.556 s    10 runs
+
+  Summary
+    With ThinLTO cache ran
+      1.20 ± 0.01 times faster than Without ThinLTO cache
+
+ARCH=x86_64 defconfig + CONFIG_LTO_CLANG_THIN=y on an x86_64 host:
+
+  Benchmark 1: With ThinLTO cache
+    Time (mean ± σ):     85.772 s ±  0.252 s    [User: 91.505 s, System: 8.408 s]
+    Range (min … max):   85.447 s … 86.244 s    10 runs
+
+  Benchmark 2: Without ThinLTO cache
+    Time (mean ± σ):     103.833 s ±  0.288 s    [User: 232.058 s, System: 8.569 s]
+    Range (min … max):   103.286 s … 104.124 s    10 runs
+
+  Summary
+    With ThinLTO cache ran
+      1.21 ± 0.00 times faster than Without ThinLTO cache
+
+While it is unfortunate to take this performance improvement off the
+table, correctness is more important. If/when this is fixed in LLVM, it
+can potentially be brought back in a conditional manner. Alternatively,
+a developer can just disable LTO if doing incremental compiles quickly
+is important, as a full compile cycle can still take over a minute even
+with the cache and it is unlikely that LTO will result in functional
+differences for a kernel change.
+
+Cc: stable@vger.kernel.org
+Fixes: dc5723b02e52 ("kbuild: add support for Clang LTO")
+Reported-by: Yifan Hong <elsk@google.com>
+Closes: https://github.com/ClangBuiltLinux/linux/issues/2021
+Reported-by: Masami Hiramatsu <mhiramat@kernel.org>
+Closes: https://lore.kernel.org/r/20220327115526.cc4b0ff55fc53c97683c3e4d@kernel.org/
+Signed-off-by: Nathan Chancellor <nathan@kernel.org>
+Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
+[nathan: Address conflict in Makefile]
+Signed-off-by: Nathan Chancellor <nathan@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ Makefile |    5 ++---
+ 1 file changed, 2 insertions(+), 3 deletions(-)
+
+--- a/Makefile
++++ b/Makefile
+@@ -959,7 +959,6 @@ endif
+ ifdef CONFIG_LTO_CLANG
+ ifdef CONFIG_LTO_CLANG_THIN
+ CC_FLAGS_LTO  := -flto=thin -fsplit-lto-unit
+-KBUILD_LDFLAGS        += --thinlto-cache-dir=$(extmod_prefix).thinlto-cache
+ else
+ CC_FLAGS_LTO  := -flto
+ endif
+@@ -1560,7 +1559,7 @@ endif # CONFIG_MODULES
+ # Directories & files removed with 'make clean'
+ CLEAN_FILES += include/ksym vmlinux.symvers modules-only.symvers \
+              modules.builtin modules.builtin.modinfo modules.nsdeps \
+-             compile_commands.json .thinlto-cache
++             compile_commands.json
+ 
+ # Directories & files removed with 'make mrproper'
+ MRPROPER_FILES += include/config include/generated          \
+@@ -1788,7 +1787,7 @@ PHONY += compile_commands.json
+ 
+ clean-dirs := $(KBUILD_EXTMOD)
+ clean: rm-files := $(KBUILD_EXTMOD)/Module.symvers $(KBUILD_EXTMOD)/modules.nsdeps \
+-      $(KBUILD_EXTMOD)/compile_commands.json $(KBUILD_EXTMOD)/.thinlto-cache
++      $(KBUILD_EXTMOD)/compile_commands.json
+ 
+ PHONY += prepare
+ # now expand this into a simple variable to reduce the cost of shell evaluations

diff --git a/queue-5.15/series b/queue-5.15/series
index 7ee2c13c78dde5ebfe03f7323b2d8cdcbe0c656c..7f8740a339276d0291356ad8247427941788d443 100644 (file)
--- a/queue-5.15/series
+++ b/queue-5.15/series
@@ -170,3 +170,4 @@ serial-8250_pxa-configure-tx_loadsz-to-match-fifo-irq-level.patch
 hugetlb_encode.h-fix-undefined-behaviour-34-26.patch
 mptcp-pm-inc-rmaddr-mib-counter-once-per-rm_addr-id.patch
 mptcp-pm-update-add_addr-counters-after-connect.patch
+kbuild-remove-support-for-clang-s-thinlto-caching.patch