From: Fangrui Song <maskray@google.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org
Cc: Jisheng Zhang <jszhang@kernel.org>,
Ard Biesheuvel <ardb@kernel.org>,
llvm@lists.linux.dev, linux-kernel@vger.kernel.org,
Fangrui Song <maskray@google.com>
Subject: [PATCH] arm64: jump_label: use constraint "S" instead of "i"
Date: Tue, 30 Jan 2024 22:53:22 -0800 [thread overview]
Message-ID: <20240131065322.1126831-1-maskray@google.com> (raw)
The constraint "i" seems to be copied from x86 (and with a redundant
modifier "c"). It works with -fno-PIE but not with -fPIE/-fPIC in GCC's
aarch64 port.
The constraint "S", which denotes a symbol reference (e.g. function,
global variable) or label reference, is more appropriate, and has been
available in GCC since 2012 and in Clang since 7.0.
Signed-off-by: Fangrui Song <maskray@google.com>
Link: https://maskray.me/blog/2024-01-30-raw-symbol-names-in-inline-assembly
---
arch/arm64/include/asm/jump_label.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/include/asm/jump_label.h b/arch/arm64/include/asm/jump_label.h
index 48ddc0f45d22..31862b3bb33d 100644
--- a/arch/arm64/include/asm/jump_label.h
+++ b/arch/arm64/include/asm/jump_label.h
@@ -23,9 +23,9 @@ static __always_inline bool arch_static_branch(struct static_key * const key,
" .pushsection __jump_table, \"aw\" \n\t"
" .align 3 \n\t"
" .long 1b - ., %l[l_yes] - . \n\t"
- " .quad %c0 - . \n\t"
+ " .quad %0 - . \n\t"
" .popsection \n\t"
- : : "i"(&((char *)key)[branch]) : : l_yes);
+ : : "S"(&((char *)key)[branch]) : : l_yes);
return false;
l_yes:
@@ -40,9 +40,9 @@ static __always_inline bool arch_static_branch_jump(struct static_key * const ke
" .pushsection __jump_table, \"aw\" \n\t"
" .align 3 \n\t"
" .long 1b - ., %l[l_yes] - . \n\t"
- " .quad %c0 - . \n\t"
+ " .quad %0 - . \n\t"
" .popsection \n\t"
- : : "i"(&((char *)key)[branch]) : : l_yes);
+ : : "S"(&((char *)key)[branch]) : : l_yes);
return false;
l_yes:
--
2.43.0.429.g432eaa2c6b-goog
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next reply other threads:[~2024-01-31 6:53 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-31 6:53 Fangrui Song [this message]
2024-01-31 7:16 ` [PATCH] arm64: jump_label: use constraint "S" instead of "i" Ard Biesheuvel
2024-01-31 13:01 ` Dave Martin
2024-02-01 4:55 ` Fangrui Song
2024-02-01 8:08 ` Ard Biesheuvel
2024-02-01 9:11 ` Fangrui Song
2024-02-01 11:49 ` Dave Martin
2024-02-01 16:07 ` Ard Biesheuvel
2024-02-01 17:29 ` Dave Martin
2024-02-01 20:56 ` Fangrui Song
2024-02-01 21:23 ` Ard Biesheuvel
2024-02-01 22:12 ` Fangrui Song
2024-02-02 15:42 ` Dave Martin
2024-02-02 22:28 ` Fangrui Song
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