From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andy Lutomirski <luto@amacapital.net>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Lutomirski <luto@kernel.org>,
the arch/x86 maintainers <x86@kernel.org>,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
mhiramat@kernel.org, jbaron@akamai.com,
Jiri Kosina <jkosina@suse.cz>,
David.Laight@aculab.com, bp@alien8.de, julia@ni.com,
jeyu@kernel.org, Peter Anvin <hpa@zytor.com>
Subject: Re: [PATCH v2 4/4] x86/static_call: Add inline static call implementation for x86-64
Date: Thu, 29 Nov 2018 13:22:11 -0600 [thread overview]
Message-ID: <20181129192211.ndzj2ltzx5t6x2qe@treble> (raw)
In-Reply-To: <20181129141648.6ef944a9@gandalf.local.home>
On Thu, Nov 29, 2018 at 02:16:48PM -0500, Steven Rostedt wrote:
> > and honestly, the way "static_call()" works now, can you guarantee
> > that the call-site doesn't end up doing that, and calling the
> > trampoline function for two different static calls from one indirect
> > call?
> >
> > See what I'm talking about? Saying "callers are wrapped in macros"
> > doesn't actually protect you from the compiler doing things like that.
> >
> > In contrast, if the call was wrapped in an inline asm, we'd *know* the
> > compiler couldn't turn a "call wrapper(%rip)" into anything else.
>
> But then we need to implement all numbers of parameters.
I actually have an old unfinished patch which (ab)used C macros to
detect the number of parameters and then setup the asm constraints
accordingly. At the time, the goal was to optimize the BUG code.
I had wanted to avoid this kind of approach for static calls, because
"ugh", but now it's starting to look much more appealing.
Behold:
diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h
index aa6b2023d8f8..d63e9240da77 100644
--- a/arch/x86/include/asm/bug.h
+++ b/arch/x86/include/asm/bug.h
@@ -32,10 +32,59 @@
#ifdef CONFIG_DEBUG_BUGVERBOSE
-#define _BUG_FLAGS(ins, flags) \
+#define __BUG_ARGS_0(ins, ...) \
+({\
+ asm volatile("1:\t" ins "\n"); \
+})
+#define __BUG_ARGS_1(ins, ...) \
+({\
+ asm volatile("1:\t" ins "\n" \
+ : : "D" (ARG1(__VA_ARGS__))); \
+})
+#define __BUG_ARGS_2(ins, ...) \
+({\
+ asm volatile("1:\t" ins "\n" \
+ : : "D" (ARG1(__VA_ARGS__)), \
+ "S" (ARG2(__VA_ARGS__))); \
+})
+#define __BUG_ARGS_3(ins, ...) \
+({\
+ asm volatile("1:\t" ins "\n" \
+ : : "D" (ARG1(__VA_ARGS__)), \
+ "S" (ARG2(__VA_ARGS__)), \
+ "d" (ARG3(__VA_ARGS__))); \
+})
+#define __BUG_ARGS_4(ins, ...) \
+({\
+ asm volatile("1:\t" ins "\n" \
+ : : "D" (ARG1(__VA_ARGS__)), \
+ "S" (ARG2(__VA_ARGS__)), \
+ "d" (ARG3(__VA_ARGS__)), \
+ "c" (ARG4(__VA_ARGS__))); \
+})
+#define __BUG_ARGS_5(ins, ...) \
+({\
+ register u64 __r8 asm("r8") = (u64)ARG5(__VA_ARGS__); \
+ asm volatile("1:\t" ins "\n" \
+ : : "D" (ARG1(__VA_ARGS__)), \
+ "S" (ARG2(__VA_ARGS__)), \
+ "d" (ARG3(__VA_ARGS__)), \
+ "c" (ARG4(__VA_ARGS__)), \
+ "r" (__r8)); \
+})
+#define __BUG_ARGS_6 foo
+#define __BUG_ARGS_7 foo
+#define __BUG_ARGS_8 foo
+#define __BUG_ARGS_9 foo
+
+#define __BUG_ARGS(ins, num, ...) __BUG_ARGS_ ## num(ins, __VA_ARGS__)
+
+#define _BUG_ARGS(ins, num, ...) __BUG_ARGS(ins, num, __VA_ARGS__)
+
+#define _BUG_FLAGS(ins, flags, ...) \
do { \
- asm volatile("1:\t" ins "\n" \
- ".pushsection __bug_table,\"aw\"\n" \
+ _BUG_ARGS(ins, NUM_ARGS(__VA_ARGS__), __VA_ARGS__); \
+ asm volatile(".pushsection __bug_table,\"aw\"\n" \
"2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n" \
"\t" __BUG_REL(%c0) "\t# bug_entry::file\n" \
"\t.word %c1" "\t# bug_entry::line\n" \
@@ -76,7 +125,7 @@ do { \
unreachable(); \
} while (0)
-#define __WARN_FLAGS(flags) _BUG_FLAGS(ASM_UD0, BUGFLAG_WARNING|(flags))
+#define __WARN_FLAGS(flags, ...) _BUG_FLAGS(ASM_UD0, BUGFLAG_WARNING|(flags), __VA_ARGS__)
#include <asm-generic/bug.h>
diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index 70c7732c9594..0cb16e912c02 100644
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -58,8 +58,8 @@ struct bug_entry {
#endif
#ifdef __WARN_FLAGS
-#define __WARN_TAINT(taint) __WARN_FLAGS(BUGFLAG_TAINT(taint))
-#define __WARN_ONCE_TAINT(taint) __WARN_FLAGS(BUGFLAG_ONCE|BUGFLAG_TAINT(taint))
+#define __WARN_TAINT(taint, args...) __WARN_FLAGS(BUGFLAG_TAINT(taint), args)
+#define __WARN_ONCE_TAINT(taint, args...) __WARN_FLAGS(BUGFLAG_ONCE|BUGFLAG_TAINT(taint), args)
#define WARN_ON_ONCE(condition) ({ \
int __ret_warn_on = !!(condition); \
@@ -84,11 +84,12 @@ void warn_slowpath_fmt_taint(const char *file, const int line, unsigned taint,
extern void warn_slowpath_null(const char *file, const int line);
#ifdef __WARN_TAINT
#define __WARN() __WARN_TAINT(TAINT_WARN)
+#define __WARN_printf(args...) __WARN_TAINT(TAINT_WARN, args)
#else
#define __WARN() warn_slowpath_null(__FILE__, __LINE__)
+#define __WARN_printf(arg...) warn_slowpath_fmt(__FILE__, __LINE__, arg)
#endif
-#define __WARN_printf(arg...) warn_slowpath_fmt(__FILE__, __LINE__, arg)
#define __WARN_printf_taint(taint, arg...) \
warn_slowpath_fmt_taint(__FILE__, __LINE__, taint, arg)
/* used internally by panic.c */
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 2d2721756abf..e641552e17cf 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -192,6 +192,14 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
# define unreachable() do { } while (1)
#endif
+#define __NUM_ARGS(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, N, ...) N
+#define NUM_ARGS(...) __NUM_ARGS(0, ## __VA_ARGS__, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
+#define ARG1(_1, ...) _1
+#define ARG2(_1, _2, ...) _2
+#define ARG3(_1, _2, _3, ...) _3
+#define ARG4(_1, _2, _3, _4, ...) _4
+#define ARG5(_1, _2, _3, _4, _5, ...) _5
+
/*
* KENTRY - kernel entry point
* This can be used to annotate symbols (functions or data) that are used
--
Josh
next prev parent reply other threads:[~2018-11-29 19:22 UTC|newest]
Thread overview: 120+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-26 13:54 [PATCH v2 0/4] Static calls Josh Poimboeuf
2018-11-26 13:54 ` [PATCH v2 1/4] compiler.h: Make __ADDRESSABLE() symbol truly unique Josh Poimboeuf
2018-11-27 8:49 ` Ard Biesheuvel
2018-11-26 13:54 ` [PATCH v2 2/4] static_call: Add static call infrastructure Josh Poimboeuf
2018-11-26 13:54 ` [PATCH v2 3/4] x86/static_call: Add out-of-line static call implementation Josh Poimboeuf
2018-11-26 15:43 ` Peter Zijlstra
2018-11-26 16:19 ` Steven Rostedt
2018-11-26 13:55 ` [PATCH v2 4/4] x86/static_call: Add inline static call implementation for x86-64 Josh Poimboeuf
2018-11-26 16:02 ` Peter Zijlstra
2018-11-26 17:10 ` Josh Poimboeuf
2018-11-26 17:56 ` Josh Poimboeuf
2018-11-26 20:00 ` Peter Zijlstra
2018-11-26 20:08 ` Peter Zijlstra
2018-11-26 21:26 ` Josh Poimboeuf
2018-11-27 8:43 ` Peter Zijlstra
2018-11-27 8:50 ` Peter Zijlstra
2018-11-29 6:05 ` Andy Lutomirski
2018-11-29 9:42 ` Peter Zijlstra
2018-11-29 13:11 ` Josh Poimboeuf
2018-11-29 13:37 ` Andy Lutomirski
2018-11-29 14:38 ` Peter Zijlstra
2018-11-29 14:42 ` Jiri Kosina
2018-11-29 16:33 ` Josh Poimboeuf
2018-11-29 16:49 ` Peter Zijlstra
2018-11-29 16:59 ` Andy Lutomirski
2018-11-29 17:10 ` Josh Poimboeuf
2018-11-29 22:01 ` Peter Zijlstra
2018-11-29 22:14 ` Josh Poimboeuf
2018-11-29 22:22 ` Peter Zijlstra
2018-11-29 22:25 ` Andy Lutomirski
2018-11-29 22:30 ` Josh Poimboeuf
2018-11-29 17:15 ` Peter Zijlstra
2018-11-29 17:20 ` Steven Rostedt
2018-11-29 17:21 ` Steven Rostedt
2018-11-29 17:41 ` Andy Lutomirski
2018-11-29 17:45 ` Josh Poimboeuf
2018-11-29 17:52 ` Andy Lutomirski
2018-11-29 17:49 ` Steven Rostedt
2018-11-29 18:37 ` Josh Poimboeuf
2018-11-29 16:50 ` Linus Torvalds
2018-11-29 16:55 ` Steven Rostedt
2018-11-29 17:02 ` Andy Lutomirski
2018-11-29 17:07 ` Peter Zijlstra
2018-11-29 17:31 ` Andy Lutomirski
2018-11-29 17:35 ` Jiri Kosina
2018-11-29 17:13 ` Steven Rostedt
2018-11-29 17:35 ` Linus Torvalds
2018-11-29 17:44 ` Steven Rostedt
2018-11-29 17:50 ` Linus Torvalds
2018-11-29 17:54 ` Linus Torvalds
2018-11-29 17:58 ` Steven Rostedt
2018-11-29 18:23 ` Linus Torvalds
2018-11-29 18:47 ` Steven Rostedt
2018-11-29 18:58 ` Linus Torvalds
2018-11-29 19:08 ` Linus Torvalds
2018-11-29 19:11 ` Linus Torvalds
2018-12-10 23:58 ` Pavel Machek
2018-12-11 1:43 ` Linus Torvalds
2018-11-29 19:12 ` Steven Rostedt
2018-11-29 19:27 ` Andy Lutomirski
2018-11-29 20:24 ` Josh Poimboeuf
2018-11-29 22:17 ` Josh Poimboeuf
2018-11-29 23:04 ` Linus Torvalds
2018-11-30 16:27 ` Josh Poimboeuf
2018-12-11 9:41 ` David Laight
2018-12-11 17:19 ` Josh Poimboeuf
2018-12-12 18:29 ` Josh Poimboeuf
2018-11-30 16:42 ` Andy Lutomirski
2018-11-30 18:39 ` Josh Poimboeuf
2018-11-30 19:45 ` Linus Torvalds
2018-11-30 20:18 ` Andy Lutomirski
2018-11-30 20:28 ` Steven Rostedt
2018-11-30 20:59 ` Andy Lutomirski
2018-11-30 21:01 ` Steven Rostedt
2018-11-30 21:13 ` Jiri Kosina
2018-11-30 21:10 ` Josh Poimboeuf
2018-11-29 19:16 ` Steven Rostedt
2018-11-29 19:22 ` Josh Poimboeuf [this message]
2018-11-29 19:27 ` Steven Rostedt
2018-11-30 22:16 ` Rasmus Villemoes
2018-11-30 22:24 ` Josh Poimboeuf
2018-11-29 19:24 ` Linus Torvalds
2018-11-29 19:28 ` Andy Lutomirski
2018-11-29 19:31 ` Steven Rostedt
2018-11-29 20:12 ` Josh Poimboeuf
2018-11-29 18:00 ` Andy Lutomirski
2018-11-29 18:42 ` Linus Torvalds
2018-11-29 18:55 ` Steven Rostedt
2018-11-29 17:29 ` Linus Torvalds
2018-11-29 17:35 ` Andy Lutomirski
2018-11-26 18:28 ` Andy Lutomirski
2018-11-26 20:14 ` Josh Poimboeuf
2018-11-27 8:46 ` Peter Zijlstra
2018-11-26 16:08 ` Peter Zijlstra
2018-11-26 16:11 ` Ard Biesheuvel
2018-11-26 16:33 ` Andy Lutomirski
2018-11-26 16:39 ` Peter Zijlstra
2018-11-26 16:44 ` Josh Poimboeuf
2018-11-26 14:01 ` [PATCH v2 0/4] Static calls Josh Poimboeuf
2018-11-26 20:54 ` Steven Rostedt
2018-11-26 22:24 ` Josh Poimboeuf
2018-11-26 22:53 ` Steven Rostedt
2018-12-04 23:08 ` Steven Rostedt
2018-12-04 23:41 ` Andy Lutomirski
2018-12-05 15:04 ` Josh Poimboeuf
2018-12-05 23:36 ` Andy Lutomirski
2018-12-07 16:06 ` Edward Cree
2018-12-07 16:49 ` Edward Cree
2018-12-11 18:05 ` Josh Poimboeuf
2018-12-12 5:59 ` Nadav Amit
2018-12-12 17:11 ` Edward Cree
2018-12-12 17:47 ` [RFC/WIP PATCH 0/2] dynamic calls Edward Cree
2018-12-12 17:50 ` [RFC PATCH 1/2] static_call: fix out-of-line static call implementation Edward Cree
2018-12-12 17:52 ` [RFC PATCH 2/2] net: core: rather hacky PoC implementation of dynamic calls Edward Cree
2018-12-12 18:14 ` [PATCH v2 0/4] Static calls Nadav Amit
2018-12-12 18:33 ` Edward Cree
2018-12-12 21:15 ` Nadav Amit
2018-12-12 21:36 ` Edward Cree
2018-12-12 21:45 ` Nadav Amit
2018-12-10 23:57 ` Pavel Machek
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