From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers 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 Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- .../kconfig/tests/preprocess/builtin_func/Kconfig | 27 +++++++++++ .../tests/preprocess/builtin_func/__init__.py | 9 ++++ .../tests/preprocess/builtin_func/expected_stderr | 5 ++ .../tests/preprocess/builtin_func/expected_stdout | 1 + .../tests/preprocess/circular_expansion/Kconfig | 5 ++ .../preprocess/circular_expansion/__init__.py | 11 +++++ .../preprocess/circular_expansion/expected_stderr | 1 + scripts/kconfig/tests/preprocess/escape/Kconfig | 44 ++++++++++++++++++ .../kconfig/tests/preprocess/escape/__init__.py | 8 ++++ .../tests/preprocess/escape/expected_stderr | 10 ++++ scripts/kconfig/tests/preprocess/variable/Kconfig | 53 ++++++++++++++++++++++ .../kconfig/tests/preprocess/variable/__init__.py | 8 ++++ .../tests/preprocess/variable/expected_stderr | 9 ++++ 13 files changed, 191 insertions(+) create mode 100644 scripts/kconfig/tests/preprocess/builtin_func/Kconfig create mode 100644 scripts/kconfig/tests/preprocess/builtin_func/__init__.py create mode 100644 scripts/kconfig/tests/preprocess/builtin_func/expected_stderr create mode 100644 scripts/kconfig/tests/preprocess/builtin_func/expected_stdout create mode 100644 scripts/kconfig/tests/preprocess/circular_expansion/Kconfig create mode 100644 scripts/kconfig/tests/preprocess/circular_expansion/__init__.py create mode 100644 scripts/kconfig/tests/preprocess/circular_expansion/expected_stderr create mode 100644 scripts/kconfig/tests/preprocess/escape/Kconfig create mode 100644 scripts/kconfig/tests/preprocess/escape/__init__.py create mode 100644 scripts/kconfig/tests/preprocess/escape/expected_stderr create mode 100644 scripts/kconfig/tests/preprocess/variable/Kconfig create mode 100644 scripts/kconfig/tests/preprocess/variable/__init__.py create mode 100644 scripts/kconfig/tests/preprocess/variable/expected_stderr (limited to 'scripts/kconfig/tests/preprocess') diff --git a/scripts/kconfig/tests/preprocess/builtin_func/Kconfig b/scripts/kconfig/tests/preprocess/builtin_func/Kconfig new file mode 100644 index 000000000..baa328827 --- /dev/null +++ b/scripts/kconfig/tests/preprocess/builtin_func/Kconfig @@ -0,0 +1,27 @@ +# SPDX-License-Identifier: GPL-2.0 + +# 'info' prints the argument to stdout. +$(info,hello world 0) + +# 'warning-if', if the first argument is y, sends the second argument to stderr, +# and the message is prefixed with the current file name and line number. +$(warning-if,y,hello world 1) + +# 'error-if' is similar, but it terminates the parsing immediately. +# The following is just no-op since the first argument is not y. +$(error-if,n,this should not be printed) + +# Shorthand +warning = $(warning-if,y,$(1)) + +# 'shell' executes a command, and returns its stdout. +$(warning,$(shell,echo hello world 3)) + +# Every newline in the output is replaced with a space, +# but any trailing newlines are deleted. +$(warning,$(shell,printf 'hello\nworld\n\n4\n\n\n')) + +# 'filename' is expanded to the currently parsed file name, +# 'lineno' to the line number. +$(warning,filename=$(filename)) +$(warning,lineno=$(lineno)) diff --git a/scripts/kconfig/tests/preprocess/builtin_func/__init__.py b/scripts/kconfig/tests/preprocess/builtin_func/__init__.py new file mode 100644 index 000000000..2e53ba08f --- /dev/null +++ b/scripts/kconfig/tests/preprocess/builtin_func/__init__.py @@ -0,0 +1,9 @@ +# SPDX-License-Identifier: GPL-2.0 +""" +Built-in function tests. +""" + +def test(conf): + assert conf.oldaskconfig() == 0 + assert conf.stdout_contains('expected_stdout') + assert conf.stderr_matches('expected_stderr') diff --git a/scripts/kconfig/tests/preprocess/builtin_func/expected_stderr b/scripts/kconfig/tests/preprocess/builtin_func/expected_stderr new file mode 100644 index 000000000..33ea9ca38 --- /dev/null +++ b/scripts/kconfig/tests/preprocess/builtin_func/expected_stderr @@ -0,0 +1,5 @@ +Kconfig:8: hello world 1 +Kconfig:18: hello world 3 +Kconfig:22: hello world 4 +Kconfig:26: filename=Kconfig +Kconfig:27: lineno=27 diff --git a/scripts/kconfig/tests/preprocess/builtin_func/expected_stdout b/scripts/kconfig/tests/preprocess/builtin_func/expected_stdout new file mode 100644 index 000000000..82de3a7e9 --- /dev/null +++ b/scripts/kconfig/tests/preprocess/builtin_func/expected_stdout @@ -0,0 +1 @@ +hello world 0 diff --git a/scripts/kconfig/tests/preprocess/circular_expansion/Kconfig b/scripts/kconfig/tests/preprocess/circular_expansion/Kconfig new file mode 100644 index 000000000..6838997c2 --- /dev/null +++ b/scripts/kconfig/tests/preprocess/circular_expansion/Kconfig @@ -0,0 +1,5 @@ +# SPDX-License-Identifier: GPL-2.0 + +X = $(Y) +Y = $(X) +$(info $(X)) diff --git a/scripts/kconfig/tests/preprocess/circular_expansion/__init__.py b/scripts/kconfig/tests/preprocess/circular_expansion/__init__.py new file mode 100644 index 000000000..419bda3e0 --- /dev/null +++ b/scripts/kconfig/tests/preprocess/circular_expansion/__init__.py @@ -0,0 +1,11 @@ +# SPDX-License-Identifier: GPL-2.0 +""" +Detect circular variable expansion. + +If a recursively expanded variable references itself (eventually), +it should fail with an error message. +""" + +def test(conf): + assert conf.oldaskconfig() != 0 + assert conf.stderr_matches('expected_stderr') diff --git a/scripts/kconfig/tests/preprocess/circular_expansion/expected_stderr b/scripts/kconfig/tests/preprocess/circular_expansion/expected_stderr new file mode 100644 index 000000000..cde68fa98 --- /dev/null +++ b/scripts/kconfig/tests/preprocess/circular_expansion/expected_stderr @@ -0,0 +1 @@ +Kconfig:5: Recursive variable 'X' references itself (eventually) diff --git a/scripts/kconfig/tests/preprocess/escape/Kconfig b/scripts/kconfig/tests/preprocess/escape/Kconfig new file mode 100644 index 000000000..4e3f44445 --- /dev/null +++ b/scripts/kconfig/tests/preprocess/escape/Kconfig @@ -0,0 +1,44 @@ +# SPDX-License-Identifier: GPL-2.0 + +# Shorthand +warning = $(warning-if,y,$(1)) + +# You can not pass commas directly to a function since they are treated as +# delimiters. You can use the following trick to do so. +comma := , +$(warning,hello$(comma) world) + +# Like Make, single quotes, double quotes, spaces are treated verbatim. +# The following prints the text as-is. +$(warning, ' " '" ' ''' "'") + +# Unlike Make, '$' has special meaning only when it is followed by '('. +# No need to escape '$' itself. +$(warning,$) +$(warning,$$) +$ := 1 +$(warning,$($)) + +# You need a trick to escape '$' followed by '(' +# The following should print "$(X)". It should not be expanded further. +dollar := $ +$(warning,$(dollar)(X)) + +# You need a trick to treat unbalanced parentheses. +# The following should print "(". +left_paren := ( +$(warning,$(left_paren)) + +# A simple expanded should not be expanded multiple times. +# The following should print "$(X)". It should not be expanded further. +Y := $(dollar)(X) +$(warning,$(Y)) + +# The following should print "$(X)" as well. +Y = $(dollar)(X) +$(warning,$(Y)) + +# The following should print "$(". +# It should not be emit "unterminated reference" error. +unterminated := $(dollar)( +$(warning,$(unterminated)) diff --git a/scripts/kconfig/tests/preprocess/escape/__init__.py b/scripts/kconfig/tests/preprocess/escape/__init__.py new file mode 100644 index 000000000..7ee8e747f --- /dev/null +++ b/scripts/kconfig/tests/preprocess/escape/__init__.py @@ -0,0 +1,8 @@ +# SPDX-License-Identifier: GPL-2.0 +""" +Escape sequence tests. +""" + +def test(conf): + assert conf.oldaskconfig() == 0 + assert conf.stderr_matches('expected_stderr') diff --git a/scripts/kconfig/tests/preprocess/escape/expected_stderr b/scripts/kconfig/tests/preprocess/escape/expected_stderr new file mode 100644 index 000000000..1c00957dd --- /dev/null +++ b/scripts/kconfig/tests/preprocess/escape/expected_stderr @@ -0,0 +1,10 @@ +Kconfig:9: hello, world +Kconfig:13: ' " '" ' ''' "'" +Kconfig:17: $ +Kconfig:18: $$ +Kconfig:20: 1 +Kconfig:25: $(X) +Kconfig:30: ( +Kconfig:35: $(X) +Kconfig:39: $(X) +Kconfig:44: $( diff --git a/scripts/kconfig/tests/preprocess/variable/Kconfig b/scripts/kconfig/tests/preprocess/variable/Kconfig new file mode 100644 index 000000000..9ce2f95cb --- /dev/null +++ b/scripts/kconfig/tests/preprocess/variable/Kconfig @@ -0,0 +1,53 @@ +# SPDX-License-Identifier: GPL-2.0 + +# Shorthand +warning = $(warning-if,y,$(1)) + +# Simply expanded variable. +X := 1 +SIMPLE := $(X) +X := 2 +$(warning,SIMPLE = $(SIMPLE)) + +# Recursively expanded variable. +X := 1 +RECURSIVE = $(X) +X := 2 +$(warning,RECURSIVE = $(RECURSIVE)) + +# Append something to a simply expanded variable. +Y := 3 +SIMPLE += $(Y) +Y := 4 +$(warning,SIMPLE = $(SIMPLE)) + +# Append something to a recursively expanded variable. +Y := 3 +RECURSIVE += $(Y) +Y := 4 +$(warning,RECURSIVE = $(RECURSIVE)) + +# Use += operator to an undefined variable. +# This works as a recursively expanded variable. +Y := 3 +UNDEFINED_VARIABLE += $(Y) +Y := 4 +$(warning,UNDEFINED_VARIABLE = $(UNDEFINED_VARIABLE)) + +# You can use variable references for the lefthand side of assignment statement. +X := A +Y := B +$(X)$(Y) := 5 +$(warning,AB = $(AB)) + +# User-defined function. +greeting = $(1), my name is $(2). +$(warning,$(greeting,Hello,John)) + +# The number of arguments is not checked for user-defined functions. +# If some arguments are optional, it is useful to pass fewer parameters. +# $(2) will be blank in this case. +$(warning,$(greeting,Hello)) + +# Unreferenced parameters are just ignored. +$(warning,$(greeting,Hello,John,ignored,ignored)) diff --git a/scripts/kconfig/tests/preprocess/variable/__init__.py b/scripts/kconfig/tests/preprocess/variable/__init__.py new file mode 100644 index 000000000..e88b1708d --- /dev/null +++ b/scripts/kconfig/tests/preprocess/variable/__init__.py @@ -0,0 +1,8 @@ +# SPDX-License-Identifier: GPL-2.0 +""" +Variable and user-defined function tests. +""" + +def test(conf): + assert conf.oldaskconfig() == 0 + assert conf.stderr_matches('expected_stderr') diff --git a/scripts/kconfig/tests/preprocess/variable/expected_stderr b/scripts/kconfig/tests/preprocess/variable/expected_stderr new file mode 100644 index 000000000..a4841c3fd --- /dev/null +++ b/scripts/kconfig/tests/preprocess/variable/expected_stderr @@ -0,0 +1,9 @@ +Kconfig:10: SIMPLE = 1 +Kconfig:16: RECURSIVE = 2 +Kconfig:22: SIMPLE = 1 3 +Kconfig:28: RECURSIVE = 2 4 +Kconfig:35: UNDEFINED_VARIABLE = 4 +Kconfig:41: AB = 5 +Kconfig:45: Hello, my name is John. +Kconfig:50: Hello, my name is . +Kconfig:53: Hello, my name is John. -- cgit v1.3.1