patches: stable: Apply Hexagon fix

The bcachefs commit that introduced the infinite loop that this patch
works around was merged in 6.12, so this fix is needed in stable after
the bump in #789.

Signed-off-by: Nathan Chancellor <[email protected]>

Author: nathanchance

patches/stable/series

@@ -1 +1,2 @@
 20241018_arnd_media_mediatek_vcodec_mark_vdec_vp9_slice_map_counts_eob_coef_noinline.patch
+v2_20241121_nathan_hexagon_disable_constant_extender_optimization_for_llvm_prior_to_19_1_0.patch

patches/stable/v2_20241121_nathan_hexagon_disable_constant_extender_optimization_for_llvm_prior_to_19_1_0.patch

@@ -0,0 +1,73 @@
+From git@z Thu Jan  1 00:00:00 1970
+Subject: [PATCH v2] hexagon: Disable constant extender optimization for
+ LLVM prior to 19.1.0
+From: Nathan Chancellor <[email protected]>
+Date: Thu, 21 Nov 2024 11:22:18 -0700
+Message-Id: <20241121-hexagon-disable-constant-expander-pass-v2-1-1a92e9afb0f4@kernel.org>
+MIME-Version: 1.0
+Content-Type: text/plain; charset="utf-8"
+Content-Transfer-Encoding: 7bit
+
+The Hexagon-specific constant extender optimization in LLVM may crash on
+Linux kernel code [1], such as fs/bcache/btree_io.c after
+commit 32ed4a620c54 ("bcachefs: Btree path tracepoints") in 6.12:
+
+  clang: llvm/lib/Target/Hexagon/HexagonConstExtenders.cpp:745: bool (anonymous namespace)::HexagonConstExtenders::ExtRoot::operator<(const HCE::ExtRoot &) const: Assertion `ThisB->getParent() == OtherB->getParent()' failed.
+  Stack dump:
+  0.      Program arguments: clang --target=hexagon-linux-musl ... fs/bcachefs/btree_io.c
+  1.      <eof> parser at end of file
+  2.      Code generation
+  3.      Running pass 'Function Pass Manager' on module 'fs/bcachefs/btree_io.c'.
+  4.      Running pass 'Hexagon constant-extender optimization' on function '@__btree_node_lock_nopath'
+
+Without assertions enabled, there is just a hang during compilation.
+
+This has been resolved in LLVM main (20.0.0) [2] and backported to LLVM
+19.1.0 but the kernel supports LLVM 13.0.1 and newer, so disable the
+constant expander optimization using the '-mllvm' option when using a
+toolchain that is not fixed.
+
+Cc: [email protected]
+Link: https://github.com/llvm/llvm-project/issues/99714 [1]
+Link: https://github.com/llvm/llvm-project/commit/68df06a0b2998765cb0a41353fcf0919bbf57ddb [2]
+Link: https://github.com/llvm/llvm-project/commit/2ab8d93061581edad3501561722ebd5632d73892 [3]
+Reviewed-by: Brian Cain <[email protected]>
+Link: https://lore.kernel.org/r/20241121-hexagon-disable-constant-expander-pass-v2-1-1a92e9afb0f4@kernel.org
+Signed-off-by: Nathan Chancellor <[email protected]>
+---
+Andrew, can you please take this for 6.13? Our CI continues to hit this.
+
+Changes in v2:
+- Rebase on 6.12 to make sure it is still applicable
+- Name exact bcachefs commit that introduces crash now that it is
+  merged
+- Add 'Cc: stable' as this is now visible in a stable release
+- Carry forward Brian's reviewed-by
+- Link to v1: https://lore.kernel.org/r/20240819-hexagon-disable-constant-expander-pass-v1-1-36a734e9527d@kernel.org
+---
+ arch/hexagon/Makefile | 6 ++++++
+ 1 file changed, 6 insertions(+)
+
+diff --git a/arch/hexagon/Makefile b/arch/hexagon/Makefile
+index 92d005958dfb232d48a4ca843b46262a84a08eb4..ff172cbe5881a074f9d9430c37071992a4c8beac 100644
+--- a/arch/hexagon/Makefile
++++ b/arch/hexagon/Makefile
+@@ -32,3 +32,9 @@ KBUILD_LDFLAGS += $(ldflags-y)
+ TIR_NAME := r19
+ KBUILD_CFLAGS += -ffixed-$(TIR_NAME) -DTHREADINFO_REG=$(TIR_NAME) -D__linux__
+ KBUILD_AFLAGS += -DTHREADINFO_REG=$(TIR_NAME)
++
++# Disable HexagonConstExtenders pass for LLVM versions prior to 19.1.0
++# https://github.com/llvm/llvm-project/issues/99714
++ifneq ($(call clang-min-version, 190100),y)
++KBUILD_CFLAGS += -mllvm -hexagon-cext=false
++endif
+
+---
+base-commit: adc218676eef25575469234709c2d87185ca223a
+change-id: 20240802-hexagon-disable-constant-expander-pass-8b6b61db6afc
+
+Best regards,
+-- 
+Nathan Chancellor <[email protected]>
+