kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit
`objtool` errors such as:

    vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a:
    can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd

The reason is that in such builds, the Clang invocation that compiles
the combined Rust plus helpers bitcode emits LLVM bitcode (again) --
the final code generation happens in the linker's LTO step, which the
`-mllvm` trap options passed to Clang do not reach.

This, in turn, means that unreachable traps are missing, and the
impossible paths do not merely fallthrough to the next symbol, but past
the end of their own section, since LTO builds place each function in
its own section.

Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always
emits machine code directly, with the traps in place.

Assisted-by: LLM
Cc: Gary Guo <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

46 files changed, 190 insertions, 0 deletions

diff --git a/tools/bootconfig/samples/bad-array-after-comment.bconf b/tools/bootconfig/samples/bad-array-after-comment.bconf
new file mode 100644
index 000000000..fdb6d4e04
--- /dev/null
+++ b/tools/bootconfig/samples/bad-array-after-comment.bconf
@@ -0,0 +1,4 @@
+# the first array value must be on the same line as the key
+key = # comment
+ value1,
+ value2
diff --git a/tools/bootconfig/samples/bad-array-in-next-line.bconf b/tools/bootconfig/samples/bad-array-in-next-line.bconf
new file mode 100644
index 000000000..95a99a3bd
--- /dev/null
+++ b/tools/bootconfig/samples/bad-array-in-next-line.bconf
@@ -0,0 +1,4 @@
+# the first array value must be on the same line as the key
+key =
+  value1,
+  value2
diff --git a/tools/bootconfig/samples/bad-array-space-comment.bconf b/tools/bootconfig/samples/bad-array-space-comment.bconf
new file mode 100644
index 000000000..fda19e47d
--- /dev/null
+++ b/tools/bootconfig/samples/bad-array-space-comment.bconf
@@ -0,0 +1,5 @@
+key =	# comment
+	"value1",	  # comment1
+	"value2" 	  # comment2
+,
+	"value3"
diff --git a/tools/bootconfig/samples/bad-array.bconf b/tools/bootconfig/samples/bad-array.bconf
new file mode 100644
index 000000000..0174af019
--- /dev/null
+++ b/tools/bootconfig/samples/bad-array.bconf
@@ -0,0 +1,2 @@
+# Array must be comma separated.
+key = "value1" "value2"
diff --git a/tools/bootconfig/samples/bad-dotword.bconf b/tools/bootconfig/samples/bad-dotword.bconf
new file mode 100644
index 000000000..ba5557b2b
--- /dev/null
+++ b/tools/bootconfig/samples/bad-dotword.bconf
@@ -0,0 +1,4 @@
+# do not start keyword with .
+key {
+  .word = 1
+}
diff --git a/tools/bootconfig/samples/bad-empty.bconf b/tools/bootconfig/samples/bad-empty.bconf
new file mode 100644
index 000000000..2ba3f6cc6
--- /dev/null
+++ b/tools/bootconfig/samples/bad-empty.bconf
@@ -0,0 +1 @@
+# Wrong boot config: comment only
diff --git a/tools/bootconfig/samples/bad-keyerror.bconf b/tools/bootconfig/samples/bad-keyerror.bconf
new file mode 100644
index 000000000..b6e247a09
--- /dev/null
+++ b/tools/bootconfig/samples/bad-keyerror.bconf
@@ -0,0 +1,2 @@
+# key word can not contain ","
+key,word
diff --git a/tools/bootconfig/samples/bad-longkey.bconf b/tools/bootconfig/samples/bad-longkey.bconf
new file mode 100644
index 000000000..eb97369f9
--- /dev/null
+++ b/tools/bootconfig/samples/bad-longkey.bconf
@@ -0,0 +1 @@
+key_word_is_too_long01234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345
diff --git a/tools/bootconfig/samples/bad-manywords.bconf b/tools/bootconfig/samples/bad-manywords.bconf
new file mode 100644
index 000000000..8db81967c
--- /dev/null
+++ b/tools/bootconfig/samples/bad-manywords.bconf
@@ -0,0 +1 @@
+key1.is2.too3.long4.5.6.7.8.9.10.11.12.13.14.15.16.17
diff --git a/tools/bootconfig/samples/bad-no-keyword.bconf b/tools/bootconfig/samples/bad-no-keyword.bconf
new file mode 100644
index 000000000..eff268085
--- /dev/null
+++ b/tools/bootconfig/samples/bad-no-keyword.bconf
@@ -0,0 +1,2 @@
+# No keyword
+{}
diff --git a/tools/bootconfig/samples/bad-non-closed-brace.bconf b/tools/bootconfig/samples/bad-non-closed-brace.bconf
new file mode 100644
index 000000000..6ed9f3363
--- /dev/null
+++ b/tools/bootconfig/samples/bad-non-closed-brace.bconf
@@ -0,0 +1,4 @@
+foo {
+ bar {
+   buz
+ }
diff --git a/tools/bootconfig/samples/bad-nonprintable.bconf b/tools/bootconfig/samples/bad-nonprintable.bconf
new file mode 100644
index 000000000..3bb1a2864
--- /dev/null
+++ b/tools/bootconfig/samples/bad-nonprintable.bconf
@@ -0,0 +1,2 @@
+# Non printable
+key = ""
diff --git a/tools/bootconfig/samples/bad-over-max-brace.bconf b/tools/bootconfig/samples/bad-over-max-brace.bconf
new file mode 100644
index 000000000..74b5dc9e2
--- /dev/null
+++ b/tools/bootconfig/samples/bad-over-max-brace.bconf
@@ -0,0 +1,19 @@
+key1 {
+key2 {
+key3 {
+key4 {
+key5 {
+key6 {
+key7 {
+key8 {
+key9 {
+key10 {
+key11 {
+key12 {
+key13 {
+key14 {
+key15 {
+key16 {
+key17 {
+}}}}}}}}}}}}}}}}}
+
diff --git a/tools/bootconfig/samples/bad-samekey.bconf b/tools/bootconfig/samples/bad-samekey.bconf
new file mode 100644
index 000000000..e8d983a45
--- /dev/null
+++ b/tools/bootconfig/samples/bad-samekey.bconf
@@ -0,0 +1,6 @@
+# Same key value is not allowed
+key {
+	foo = value
+	bar = value2
+}
+key.foo = value
diff --git a/tools/bootconfig/samples/bad-spaceword.bconf b/tools/bootconfig/samples/bad-spaceword.bconf
new file mode 100644
index 000000000..90c703d32
--- /dev/null
+++ b/tools/bootconfig/samples/bad-spaceword.bconf
@@ -0,0 +1,2 @@
+# No space between words
+key . word
diff --git a/tools/bootconfig/samples/bad-tree.bconf b/tools/bootconfig/samples/bad-tree.bconf
new file mode 100644
index 000000000..5a6038edc
--- /dev/null
+++ b/tools/bootconfig/samples/bad-tree.bconf
@@ -0,0 +1,5 @@
+# brace is not closing
+tree {
+  node {
+    value = 1
+}
diff --git a/tools/bootconfig/samples/bad-value.bconf b/tools/bootconfig/samples/bad-value.bconf
new file mode 100644
index 000000000..a1217fed8
--- /dev/null
+++ b/tools/bootconfig/samples/bad-value.bconf
@@ -0,0 +1,3 @@
+# Quotes error
+value = "data
+
diff --git a/tools/bootconfig/samples/escaped.bconf b/tools/bootconfig/samples/escaped.bconf
new file mode 100644
index 000000000..9f72043b3
--- /dev/null
+++ b/tools/bootconfig/samples/escaped.bconf
@@ -0,0 +1,3 @@
+key1 = "A\B\C"
+key2 = '\'\''
+key3 = "\\"
diff --git a/tools/bootconfig/samples/exp-good-array-space-comment.bconf b/tools/bootconfig/samples/exp-good-array-space-comment.bconf
new file mode 100644
index 000000000..8d3278fa6
--- /dev/null
+++ b/tools/bootconfig/samples/exp-good-array-space-comment.bconf
@@ -0,0 +1 @@
+key = "value1", "value2", "value3";
diff --git a/tools/bootconfig/samples/exp-good-comment-after-value.bconf b/tools/bootconfig/samples/exp-good-comment-after-value.bconf
new file mode 100644
index 000000000..a8e8450db
--- /dev/null
+++ b/tools/bootconfig/samples/exp-good-comment-after-value.bconf
@@ -0,0 +1 @@
+key = "value";
diff --git a/tools/bootconfig/samples/exp-good-mixed-append.bconf b/tools/bootconfig/samples/exp-good-mixed-append.bconf
new file mode 100644
index 000000000..c2b407901
--- /dev/null
+++ b/tools/bootconfig/samples/exp-good-mixed-append.bconf
@@ -0,0 +1,2 @@
+key = "foo", "bar";
+keyx.subkey = "value";
diff --git a/tools/bootconfig/samples/exp-good-mixed-kv1.bconf b/tools/bootconfig/samples/exp-good-mixed-kv1.bconf
new file mode 100644
index 000000000..8346287d9
--- /dev/null
+++ b/tools/bootconfig/samples/exp-good-mixed-kv1.bconf
@@ -0,0 +1,2 @@
+key = "value";
+key.subkey = "another-value";
diff --git a/tools/bootconfig/samples/exp-good-mixed-kv2.bconf b/tools/bootconfig/samples/exp-good-mixed-kv2.bconf
new file mode 100644
index 000000000..40c6232c7
--- /dev/null
+++ b/tools/bootconfig/samples/exp-good-mixed-kv2.bconf
@@ -0,0 +1,2 @@
+key = "another-value";
+key.subkey = "value";
diff --git a/tools/bootconfig/samples/exp-good-mixed-kv3.bconf b/tools/bootconfig/samples/exp-good-mixed-kv3.bconf
new file mode 100644
index 000000000..8368a7bef
--- /dev/null
+++ b/tools/bootconfig/samples/exp-good-mixed-kv3.bconf
@@ -0,0 +1,5 @@
+key = "value";
+key {
+	subkey1;
+	subkey2 = "foo";
+}
diff --git a/tools/bootconfig/samples/exp-good-mixed-override.bconf b/tools/bootconfig/samples/exp-good-mixed-override.bconf
new file mode 100644
index 000000000..58757712c
--- /dev/null
+++ b/tools/bootconfig/samples/exp-good-mixed-override.bconf
@@ -0,0 +1,2 @@
+key = "value2";
+key.foo = "bar";
diff --git a/tools/bootconfig/samples/exp-good-nested-brace.bconf b/tools/bootconfig/samples/exp-good-nested-brace.bconf
new file mode 100644
index 000000000..19e0f51b4
--- /dev/null
+++ b/tools/bootconfig/samples/exp-good-nested-brace.bconf
@@ -0,0 +1 @@
+key1.key2.key3.key4.key5.key6.key7.key8.key9.key10.key11.key12.key13.key14.key15.key16;
diff --git a/tools/bootconfig/samples/exp-good-override.bconf b/tools/bootconfig/samples/exp-good-override.bconf
new file mode 100644
index 000000000..00bbd30e9
--- /dev/null
+++ b/tools/bootconfig/samples/exp-good-override.bconf
@@ -0,0 +1,4 @@
+key {
+	word = "2", "3";
+	new.word = "new";
+}
diff --git a/tools/bootconfig/samples/exp-good-printables.bconf b/tools/bootconfig/samples/exp-good-printables.bconf
new file mode 100644
index 000000000..5981d304e
--- /dev/null
+++ b/tools/bootconfig/samples/exp-good-printables.bconf
@@ -0,0 +1,2 @@
+key = "	
+ !#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~";
diff --git a/tools/bootconfig/samples/exp-good-simple.bconf b/tools/bootconfig/samples/exp-good-simple.bconf
new file mode 100644
index 000000000..d17f39421
--- /dev/null
+++ b/tools/bootconfig/samples/exp-good-simple.bconf
@@ -0,0 +1,8 @@
+key {
+	word1 = "1";
+	word2 = "2";
+	word3 = "3";
+	word4 = "4";
+	word5 = "5";
+	word6 = "6";
+}
diff --git a/tools/bootconfig/samples/exp-good-single.bconf b/tools/bootconfig/samples/exp-good-single.bconf
new file mode 100644
index 000000000..01196910d
--- /dev/null
+++ b/tools/bootconfig/samples/exp-good-single.bconf
@@ -0,0 +1,3 @@
+key = "1";
+key2 = "2";
+key3 = "alpha", "beta";
diff --git a/tools/bootconfig/samples/exp-good-space-after-value.bconf b/tools/bootconfig/samples/exp-good-space-after-value.bconf
new file mode 100644
index 000000000..a8e8450db
--- /dev/null
+++ b/tools/bootconfig/samples/exp-good-space-after-value.bconf
@@ -0,0 +1 @@
+key = "value";
diff --git a/tools/bootconfig/samples/exp-good-tree.bconf b/tools/bootconfig/samples/exp-good-tree.bconf
new file mode 100644
index 000000000..b711d38d8
--- /dev/null
+++ b/tools/bootconfig/samples/exp-good-tree.bconf
@@ -0,0 +1,8 @@
+key {
+	word.tree.value = "0";
+	word2.tree.value = "1", "2";
+}
+other.tree {
+	value = "2";
+	value2 = "3";
+}
diff --git a/tools/bootconfig/samples/good-array-space-comment.bconf b/tools/bootconfig/samples/good-array-space-comment.bconf
new file mode 100644
index 000000000..416fa2ed4
--- /dev/null
+++ b/tools/bootconfig/samples/good-array-space-comment.bconf
@@ -0,0 +1,3 @@
+key = "value1",	  # comment1
+	"value2"	 , # comment2
+	"value3"
diff --git a/tools/bootconfig/samples/good-comment-after-value.bconf b/tools/bootconfig/samples/good-comment-after-value.bconf
new file mode 100644
index 000000000..0d92a853d
--- /dev/null
+++ b/tools/bootconfig/samples/good-comment-after-value.bconf
@@ -0,0 +1 @@
+key = "value"  # comment
diff --git a/tools/bootconfig/samples/good-mixed-append.bconf b/tools/bootconfig/samples/good-mixed-append.bconf
new file mode 100644
index 000000000..b99a089a0
--- /dev/null
+++ b/tools/bootconfig/samples/good-mixed-append.bconf
@@ -0,0 +1,4 @@
+key = foo
+keyx.subkey = value
+key += bar
+
diff --git a/tools/bootconfig/samples/good-mixed-kv1.bconf b/tools/bootconfig/samples/good-mixed-kv1.bconf
new file mode 100644
index 000000000..1761547dd
--- /dev/null
+++ b/tools/bootconfig/samples/good-mixed-kv1.bconf
@@ -0,0 +1,3 @@
+# value -> subkey pattern
+key = value
+key.subkey = another-value
diff --git a/tools/bootconfig/samples/good-mixed-kv2.bconf b/tools/bootconfig/samples/good-mixed-kv2.bconf
new file mode 100644
index 000000000..6b32e0c38
--- /dev/null
+++ b/tools/bootconfig/samples/good-mixed-kv2.bconf
@@ -0,0 +1,3 @@
+# subkey -> value pattern
+key.subkey = value
+key = another-value
diff --git a/tools/bootconfig/samples/good-mixed-kv3.bconf b/tools/bootconfig/samples/good-mixed-kv3.bconf
new file mode 100644
index 000000000..2ce2b0222
--- /dev/null
+++ b/tools/bootconfig/samples/good-mixed-kv3.bconf
@@ -0,0 +1,6 @@
+# mixed key and subkeys with braces
+key = value
+key {
+	subkey1
+	subkey2 = foo
+}
diff --git a/tools/bootconfig/samples/good-mixed-override.bconf b/tools/bootconfig/samples/good-mixed-override.bconf
new file mode 100644
index 000000000..18195b287
--- /dev/null
+++ b/tools/bootconfig/samples/good-mixed-override.bconf
@@ -0,0 +1,4 @@
+key.foo = bar
+key = value
+# mixed key value can be overridden
+key := value2
diff --git a/tools/bootconfig/samples/good-nested-brace.bconf b/tools/bootconfig/samples/good-nested-brace.bconf
new file mode 100644
index 000000000..980d094f2
--- /dev/null
+++ b/tools/bootconfig/samples/good-nested-brace.bconf
@@ -0,0 +1,18 @@
+key1 {
+key2 {
+key3 {
+key4 {
+key5 {
+key6 {
+key7 {
+key8 {
+key9 {
+key10 {
+key11 {
+key12 {
+key13 {
+key14 {
+key15 {
+key16 {
+}}}}}}}}}}}}}}}}
+
diff --git a/tools/bootconfig/samples/good-override.bconf b/tools/bootconfig/samples/good-override.bconf
new file mode 100644
index 000000000..7d31d5f8f
--- /dev/null
+++ b/tools/bootconfig/samples/good-override.bconf
@@ -0,0 +1,6 @@
+# Override the value
+key.word = 1,2,4
+key.word := 2,3
+
+# No pre-defined key
+key.new.word := "new"
diff --git a/tools/bootconfig/samples/good-printables.bconf b/tools/bootconfig/samples/good-printables.bconf
new file mode 100644
index 000000000..ebb985a66
--- /dev/null
+++ b/tools/bootconfig/samples/good-printables.bconf
@@ -0,0 +1,2 @@
+key = "	
+ !#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~"
diff --git a/tools/bootconfig/samples/good-simple.bconf b/tools/bootconfig/samples/good-simple.bconf
new file mode 100644
index 000000000..37dd6d21c
--- /dev/null
+++ b/tools/bootconfig/samples/good-simple.bconf
@@ -0,0 +1,11 @@
+# A good simple bootconfig
+
+key.word1 = 1
+key.word2=2
+key.word3 = 3;
+
+key {
+word4 = 4 }
+
+key { word5 = 5; word6 = 6 }
+
diff --git a/tools/bootconfig/samples/good-single.bconf b/tools/bootconfig/samples/good-single.bconf
new file mode 100644
index 000000000..98e55ad8b
--- /dev/null
+++ b/tools/bootconfig/samples/good-single.bconf
@@ -0,0 +1,4 @@
+# single key style
+key = 1
+key2 = 2
+key3 = "alpha", "beta"
diff --git a/tools/bootconfig/samples/good-space-after-value.bconf b/tools/bootconfig/samples/good-space-after-value.bconf
new file mode 100644
index 000000000..56c15cbc5
--- /dev/null
+++ b/tools/bootconfig/samples/good-space-after-value.bconf
@@ -0,0 +1 @@
+key = "value"   
diff --git a/tools/bootconfig/samples/good-tree.bconf b/tools/bootconfig/samples/good-tree.bconf
new file mode 100644
index 000000000..f2ddefc8b
--- /dev/null
+++ b/tools/bootconfig/samples/good-tree.bconf
@@ -0,0 +1,12 @@
+key {
+  word {
+    tree {
+      value = "0"}
+  }
+  word2 {
+    tree {
+      value = 1,2 }
+  }
+}
+other.tree {
+  value = 2; value2 = 3;}