From: Fangrui Song <maskray@google.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
rostedt@goodmis.org, mhiramat@kernel.org, bristot@redhat.com,
jbaron@akamai.com, torvalds@linux-foundation.org,
tglx@linutronix.de, mingo@kernel.org, namit@vmware.com,
hpa@zytor.com, luto@kernel.org, ard.biesheuvel@linaro.org,
jpoimboe@redhat.com, clang-built-linux@googlegroups.com
Subject: Re: [RESEND][PATCH v3 09/17] x86/static_call: Add out-of-line static call implementation
Date: Sun, 5 Apr 2020 18:08:59 -0700 [thread overview]
Message-ID: <20200406010859.bcfouhukcgmg2on7@google.com> (raw)
In-Reply-To: <20200324142245.819003994@infradead.org>
On 2020-03-24, Peter Zijlstra wrote:
>Add the x86 out-of-line static call implementation. For each key, a
>permanent trampoline is created which is the destination for all static
>calls for the given key. The trampoline has a direct jump which gets
>patched by static_call_update() when the destination function changes.
>
>Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
>[peterz: fixed trampoline, rewrote patching code]
>Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
>---
> arch/x86/Kconfig | 1 +
> arch/x86/include/asm/static_call.h | 22 ++++++++++++++++++++++
> arch/x86/kernel/Makefile | 1 +
> arch/x86/kernel/static_call.c | 31 +++++++++++++++++++++++++++++++
> 4 files changed, 55 insertions(+)
> create mode 100644 arch/x86/include/asm/static_call.h
> create mode 100644 arch/x86/kernel/static_call.c
>
>--- a/arch/x86/Kconfig
>+++ b/arch/x86/Kconfig
>@@ -205,6 +205,7 @@ config X86
> select HAVE_FUNCTION_ARG_ACCESS_API
> select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
> select HAVE_STACK_VALIDATION if X86_64
>+ select HAVE_STATIC_CALL
> select HAVE_RSEQ
> select HAVE_SYSCALL_TRACEPOINTS
> select HAVE_UNSTABLE_SCHED_CLOCK
>--- /dev/null
>+++ b/arch/x86/include/asm/static_call.h
>@@ -0,0 +1,22 @@
>+/* SPDX-License-Identifier: GPL-2.0 */
>+#ifndef _ASM_STATIC_CALL_H
>+#define _ASM_STATIC_CALL_H
>+
>+#include <asm/text-patching.h>
>+
>+/*
>+ * For CONFIG_HAVE_STATIC_CALL, this is a permanent trampoline which
>+ * does a direct jump to the function. The direct jump gets patched by
>+ * static_call_update().
>+ */
>+#define ARCH_DEFINE_STATIC_CALL_TRAMP(name, func) \
>+ asm(".pushsection .text, \"ax\" \n" \
>+ ".align 4 \n" \
>+ ".globl " STATIC_CALL_TRAMP_STR(name) " \n" \
>+ STATIC_CALL_TRAMP_STR(name) ": \n" \
>+ " jmp.d32 " #func " \n" \
>+ ".type " STATIC_CALL_TRAMP_STR(name) ", @function \n" \
>+ ".size " STATIC_CALL_TRAMP_STR(name) ", . - " STATIC_CALL_TRAMP_STR(name) " \n" \
>+ ".popsection \n")
>+
>+#endif /* _ASM_STATIC_CALL_H */
Hi Peter,
Coming here from https://github.com/ClangBuiltLinux/linux/issues/974
jmp.d32 is not recognized by clang integrated assembler.
The syntax appears to be very rarely used. According to Debian Code Search,
u-boot is the only project using this syntax.
In March 2017, gas added the pseudo prefix {disp32}
https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=86fa6981e7487e2c2df4337aa75ed2d93c32eaf2
which generalizes jmp.d32 ({disp32} jmp foo)
I wonder whether the instruction jmp.d32 can be replaced with the trick in
arch/x86/include/asm/jump_label.h for clang portability.
% grep -A2 'jmp.d32' arch/x86/include/asm/jump_label.h
/* Equivalent to "jmp.d32 \target" */
.byte 0xe9
.long \target - .Lstatic_jump_after_\@
...
+ clang-built-linux@googlegroups.com
next prev parent reply other threads:[~2020-04-06 1:10 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-24 13:56 [RESEND][PATCH v3 00/17] Add static_call() Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 01/17] notifier: Fix broken error handling pattern Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 02/17] module: Fix up module_notifier return values Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 03/17] module: Properly propagate MODULE_STATE_COMING failure Peter Zijlstra
2020-03-25 17:35 ` Jessica Yu
2020-03-27 4:51 ` Josh Poimboeuf
2020-03-27 12:04 ` Miroslav Benes
2020-03-24 13:56 ` [RESEND][PATCH v3 04/17] jump_label,module: Fix module lifetime for __jump_label_mod_text_reserved Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 05/17] compiler.h: Make __ADDRESSABLE() symbol truly unique Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 06/17] static_call: Add basic static call infrastructure Peter Zijlstra
2020-03-26 16:42 ` Nadav Amit
2020-03-26 17:01 ` Peter Zijlstra
2020-03-26 18:09 ` Nadav Amit
2020-03-26 18:28 ` Peter Zijlstra
2020-03-26 19:02 ` Nadav Amit
2020-03-26 19:13 ` Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 07/17] static_call: Add inline " Peter Zijlstra
2020-03-26 15:54 ` Borislav Petkov
2020-03-24 13:56 ` [RESEND][PATCH v3 08/17] static_call: Avoid kprobes on inline static_call()s Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 09/17] x86/static_call: Add out-of-line static call implementation Peter Zijlstra
2020-03-26 14:57 ` Borislav Petkov
2020-04-06 1:08 ` Fangrui Song [this message]
2020-04-06 11:04 ` Peter Zijlstra
2020-04-06 18:29 ` Nick Desaulniers
2020-03-24 13:56 ` [RESEND][PATCH v3 10/17] x86/static_call: Add inline static call implementation for x86-64 Peter Zijlstra
2020-03-26 15:17 ` Borislav Petkov
2020-03-26 16:06 ` Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 11/17] static_call: Simple self-test Peter Zijlstra
2020-03-26 15:44 ` Borislav Petkov
2020-03-26 17:08 ` Peter Zijlstra
2020-03-26 17:33 ` Borislav Petkov
2020-03-24 13:56 ` [RESEND][PATCH v3 12/17] tracepoint: Optimize using static_call() Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 13/17] x86/alternatives: Teach text_poke_bp() to emulate RET Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 14/17] static_call: Add static_cond_call() Peter Zijlstra
2020-03-24 16:14 ` Linus Torvalds
2020-03-24 16:22 ` Andy Lutomirski
2020-03-24 16:33 ` Linus Torvalds
2020-03-24 17:03 ` Peter Zijlstra
2020-03-25 18:13 ` Peter Zijlstra
2020-03-25 18:26 ` Linus Torvalds
2020-03-25 19:34 ` hpa
2020-03-25 20:52 ` Linus Torvalds
2020-03-25 22:07 ` Peter Zijlstra
2020-03-24 16:54 ` Peter Zijlstra
2020-03-26 23:37 ` Rasmus Villemoes
2020-03-27 10:08 ` Peter Zijlstra
2020-03-27 13:25 ` Rasmus Villemoes
2020-03-24 13:56 ` [RESEND][PATCH v3 15/17] static_call: Handle tail-calls Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 16/17] static_call: Allow early init Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 17/17] x86/perf, static_call: Optimize x86_pmu methods Peter Zijlstra
2020-03-25 17:49 ` [RESEND][PATCH v3 00/17] Add static_call() Peter Zijlstra
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