diff options
| author | Fangrui Song <maskray@google.com> | 2020-04-14 09:32:55 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-05-02 08:51:02 +0200 |
| commit | 4e579d7f93ae4d5b74c83e5c72a12dd8fdf6f3bf (patch) | |
| tree | 92ae54e83b88f48f7aa354a6bb44e7a84e6f39a7 | |
| parent | cb0986223caa3f2cc9dd8be3b556fd6f03d94f05 (diff) | |
arm64: Delete the space separator in __emit_inst
[ Upstream commit c9a4ef66450145a356a626c833d3d7b1668b3ded ]
In assembly, many instances of __emit_inst(x) expand to a directive. In
a few places __emit_inst(x) is used as an assembler macro argument. For
example, in arch/arm64/kvm/hyp/entry.S
ALTERNATIVE(nop, SET_PSTATE_PAN(1), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
expands to the following by the C preprocessor:
alternative_insn nop, .inst (0xd500401f | ((0) << 16 | (4) << 5) | ((!!1) << 8)), 4, 1
Both comma and space are separators, with an exception that content
inside a pair of parentheses/quotes is not split, so the clang
integrated assembler splits the arguments to:
nop, .inst, (0xd500401f | ((0) << 16 | (4) << 5) | ((!!1) << 8)), 4, 1
GNU as preprocesses the input with do_scrub_chars(). Its arm64 backend
(along with many other non-x86 backends) sees:
alternative_insn nop,.inst(0xd500401f|((0)<<16|(4)<<5)|((!!1)<<8)),4,1
# .inst(...) is parsed as one argument
while its x86 backend sees:
alternative_insn nop,.inst (0xd500401f|((0)<<16|(4)<<5)|((!!1)<<8)),4,1
# The extra space before '(' makes the whole .inst (...) parsed as two arguments
The non-x86 backend's behavior is considered unintentional
(https://sourceware.org/bugzilla/show_bug.cgi?id=25750).
So drop the space separator inside `.inst (...)` to make the clang
integrated assembler work.
Suggested-by: Ilie Halip <ilie.halip@gmail.com>
Signed-off-by: Fangrui Song <maskray@google.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/939
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | arch/arm64/include/asm/sysreg.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index b91570ff9db1..931037500e83 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -49,7 +49,9 @@ #ifndef CONFIG_BROKEN_GAS_INST #ifdef __ASSEMBLY__ -#define __emit_inst(x) .inst (x) +// The space separator is omitted so that __emit_inst(x) can be parsed as +// either an assembler directive or an assembler macro argument. +#define __emit_inst(x) .inst(x) #else #define __emit_inst(x) ".inst " __stringify((x)) "\n\t" #endif |