From: Peter Zijlstra <peterz@infradead.org>
To: x86@kernel.org
Cc: peterz@infradead.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, pbonzini@redhat.com,
mathieu.desnoyers@efficios.com
Subject: [PATCH v4 14/18] static_call: Add static_cond_call()
Date: Fri, 01 May 2020 22:29:03 +0200 [thread overview]
Message-ID: <20200501202944.593400184@infradead.org> (raw)
In-Reply-To: 20200501202849.647891881@infradead.org
Extend the static_call infrastructure to optimize the following common
pattern:
if (func_ptr)
func_ptr(args...)
For the trampoline (which is in effect a tail-call), we patch the
JMP.d32 into a RET, which then directly consumes the trampoline call.
For the in-line sites we replace the CALL with a NOP5.
NOTE: this is 'obviously' limited to functions with a 'void' return type.
NOTE: DEFINE_STATIC_COND_CALL() only requires a typename, as opposed
to a full function.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/include/asm/static_call.h | 10 ++++++++
arch/x86/kernel/static_call.c | 42 ++++++++++++++++++++++++++++---------
include/linux/static_call.h | 29 +++++++++++++++++++++++++
3 files changed, 71 insertions(+), 10 deletions(-)
--- a/arch/x86/include/asm/static_call.h
+++ b/arch/x86/include/asm/static_call.h
@@ -30,4 +30,14 @@
".size " STATIC_CALL_TRAMP_STR(name) ", . - " STATIC_CALL_TRAMP_STR(name) " \n" \
".popsection \n")
+#define ARCH_DEFINE_STATIC_CALL_RETTRAMP(name) \
+ asm(".pushsection .static_call.text, \"ax\" \n" \
+ ".align 4 \n" \
+ ".globl " STATIC_CALL_TRAMP_STR(name) " \n" \
+ STATIC_CALL_TRAMP_STR(name) ": \n" \
+ " ret; nop; nop; nop; nop; \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 */
--- a/arch/x86/kernel/static_call.c
+++ b/arch/x86/kernel/static_call.c
@@ -4,19 +4,41 @@
#include <linux/bug.h>
#include <asm/text-patching.h>
-static void __static_call_transform(void *insn, u8 opcode, void *func)
+enum insn_type {
+ call = 0, /* site call */
+ nop = 1, /* site cond-call */
+ jmp = 2, /* tramp / site tail-call */
+ ret = 3, /* tramp / site cond-tail-call */
+};
+
+static void __static_call_transform(void *insn, enum insn_type type, void *func)
{
- const void *code = text_gen_insn(opcode, insn, func);
+ int size = CALL_INSN_SIZE;
+ const void *code;
- if (WARN_ONCE(*(u8 *)insn != opcode,
- "unexpected static call insn opcode 0x%x at %pS\n",
- opcode, insn))
- return;
+ switch (type) {
+ case call:
+ code = text_gen_insn(CALL_INSN_OPCODE, insn, func);
+ break;
+
+ case nop:
+ code = ideal_nops[NOP_ATOMIC5];
+ break;
+
+ case jmp:
+ code = text_gen_insn(JMP32_INSN_OPCODE, insn, func);
+ break;
+
+ case ret:
+ code = text_gen_insn(RET_INSN_OPCODE, insn, func);
+ size = RET_INSN_SIZE;
+ break;
+ }
- if (memcmp(insn, code, CALL_INSN_SIZE) == 0)
+ if (memcmp(insn, code, size) == 0)
return;
- text_poke_bp(insn, code, CALL_INSN_SIZE, NULL);
+ text_poke_bp(insn, code, size, NULL);
}
void arch_static_call_transform(void *site, void *tramp, void *func)
@@ -24,10 +46,10 @@ void arch_static_call_transform(void *si
mutex_lock(&text_mutex);
if (tramp)
- __static_call_transform(tramp, JMP32_INSN_OPCODE, func);
+ __static_call_transform(tramp, jmp + !func, func);
if (IS_ENABLED(CONFIG_HAVE_STATIC_CALL_INLINE) && site)
- __static_call_transform(site, CALL_INSN_OPCODE, func);
+ __static_call_transform(site, !func, func);
mutex_unlock(&text_mutex);
}
--- a/include/linux/static_call.h
+++ b/include/linux/static_call.h
@@ -16,7 +16,9 @@
*
* DECLARE_STATIC_CALL(name, func);
* DEFINE_STATIC_CALL(name, func);
+ * DEFINE_STATIC_COND_CALL(name, typename);
* static_call(name)(args...);
+ * static_cond_call(name)(args...)
* static_call_update(name, func);
*
* Usage example:
@@ -120,7 +122,16 @@ extern int static_call_text_reserved(voi
}; \
ARCH_DEFINE_STATIC_CALL_TRAMP(name, _func)
+#define DEFINE_STATIC_COND_CALL(name, _func) \
+ DECLARE_STATIC_CALL(name, _func); \
+ struct static_call_key STATIC_CALL_KEY(name) = { \
+ .func = NULL, \
+ .type = 1, \
+ }; \
+ ARCH_DEFINE_STATIC_CALL_RETTRAMP(name)
+
#define static_call(name) __static_call(name)
+#define static_cond_call(name) (void)__static_call(name)
#define EXPORT_STATIC_CALL(name) \
EXPORT_SYMBOL(STATIC_CALL_KEY(name)); \
@@ -143,7 +154,15 @@ struct static_call_key {
}; \
ARCH_DEFINE_STATIC_CALL_TRAMP(name, _func)
+#define DEFINE_STATIC_COND_CALL(name, _func) \
+ DECLARE_STATIC_CALL(name, _func); \
+ struct static_call_key STATIC_CALL_KEY(name) = { \
+ .func = NULL, \
+ }; \
+ ARCH_DEFINE_STATIC_CALL_RETTRAMP(name)
+
#define static_call(name) __static_call(name)
+#define static_cond_call(name) (void)__static_call(name)
static inline
void __static_call_update(struct static_call_key *key, void *tramp, void *func)
@@ -179,9 +198,19 @@ struct static_call_key {
.func = _func, \
}
+#define DEFINE_STATIC_COND_CALL(name, _func) \
+ DECLARE_STATIC_CALL(name, _func); \
+ struct static_call_key STATIC_CALL_KEY(name) = { \
+ .func = NULL, \
+ }
+
#define static_call(name) \
((typeof(STATIC_CALL_TRAMP(name))*)(STATIC_CALL_KEY(name).func))
+#define static_cond_call(name) \
+ if (STATIC_CALL_KEY(name).func) \
+ ((typeof(STATIC_CALL_TRAMP(name))*)(STATIC_CALL_KEY(name).func))
+
static inline
void __static_call_update(struct static_call_key *key, void *tramp, void *func)
{
next prev parent reply other threads:[~2020-05-01 20:31 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-01 20:28 [PATCH v4 00/18] Add static_call() Peter Zijlstra
2020-05-01 20:28 ` [PATCH v4 01/18] notifier: Fix broken error handling pattern Peter Zijlstra
2020-05-01 23:35 ` Steven Rostedt
2020-05-01 20:28 ` [PATCH v4 02/18] module: Fix up module_notifier return values Peter Zijlstra
2020-05-01 20:28 ` [PATCH v4 03/18] module: Properly propagate MODULE_STATE_COMING failure Peter Zijlstra
2020-05-01 20:28 ` [PATCH v4 04/18] jump_label,module: Fix module lifetime for __jump_label_mod_text_reserved Peter Zijlstra
2020-05-01 20:28 ` [PATCH v4 05/18] compiler.h: Make __ADDRESSABLE() symbol truly unique Peter Zijlstra
2020-05-01 20:28 ` [PATCH v4 06/18] static_call: Add basic static call infrastructure Peter Zijlstra
2020-05-05 21:21 ` Josh Poimboeuf
2020-05-01 20:28 ` [PATCH v4 07/18] static_call: Add inline " Peter Zijlstra
2020-05-05 22:10 ` Josh Poimboeuf
2020-05-06 16:15 ` Peter Zijlstra
2020-05-01 20:28 ` [PATCH v4 08/18] static_call: Avoid kprobes on inline static_call()s Peter Zijlstra
2020-05-01 20:28 ` [PATCH v4 09/18] x86/static_call: Add out-of-line static call implementation Peter Zijlstra
2020-05-06 16:16 ` Peter Zijlstra
2020-05-01 20:28 ` [PATCH v4 10/18] x86/static_call: Add inline static call implementation for x86-64 Peter Zijlstra
2020-05-01 20:29 ` [PATCH v4 11/18] static_call: Simple self-test Peter Zijlstra
2020-05-01 20:29 ` [PATCH v4 12/18] tracepoint: Optimize using static_call() Peter Zijlstra
2020-05-13 8:48 ` [tracepoint] 01edfaf177: WARNING:at_kernel/static_call.c:#__static_call_update kernel test robot
2020-05-15 17:13 ` Peter Zijlstra
2020-05-01 20:29 ` [PATCH v4 13/18] x86/alternatives: Teach text_poke_bp() to emulate RET Peter Zijlstra
2020-05-01 20:29 ` Peter Zijlstra [this message]
2020-05-02 13:08 ` [PATCH v4 14/18] static_call: Add static_cond_call() Rasmus Villemoes
2020-05-03 12:58 ` Peter Zijlstra
2020-05-04 7:20 ` Rasmus Villemoes
2020-05-04 20:14 ` Peter Zijlstra
2020-05-05 7:50 ` Rasmus Villemoes
2020-05-05 9:38 ` Peter Zijlstra
2020-05-05 9:36 ` Peter Zijlstra
2020-05-05 18:13 ` Nick Desaulniers
2020-05-05 18:27 ` Nick Desaulniers
2020-05-05 18:48 ` Linus Torvalds
2020-05-05 19:00 ` Mathieu Desnoyers
2020-05-05 19:57 ` Nick Desaulniers
2020-05-05 20:27 ` Mathieu Desnoyers
2020-05-06 13:55 ` Peter Zijlstra
2020-05-06 14:01 ` Mathieu Desnoyers
2020-05-06 16:18 ` Peter Zijlstra
2020-05-06 13:51 ` Peter Zijlstra
2020-05-06 16:00 ` Peter Zijlstra
2020-05-06 17:16 ` Linus Torvalds
2020-05-06 19:57 ` Andy Lutomirski
2020-05-06 17:24 ` Josh Poimboeuf
2020-05-06 17:58 ` Peter Zijlstra
2020-05-06 18:09 ` Josh Poimboeuf
2020-05-06 18:16 ` Peter Zijlstra
2020-05-08 15:27 ` Peter Zijlstra
2020-05-08 15:47 ` Josh Poimboeuf
2020-05-08 16:17 ` Peter Zijlstra
2020-05-01 20:29 ` [PATCH v4 15/18] static_call: Handle tail-calls Peter Zijlstra
2020-05-06 18:10 ` Peter Zijlstra
2020-05-01 20:29 ` [PATCH v4 16/18] static_call: Allow early init Peter Zijlstra
2020-05-06 21:15 ` Josh Poimboeuf
2020-05-08 13:31 ` Peter Zijlstra
2020-05-08 14:27 ` Josh Poimboeuf
2020-05-08 15:30 ` Peter Zijlstra
2020-05-01 20:29 ` [PATCH v4 17/18] x86/perf, static_call: Optimize x86_pmu methods Peter Zijlstra
2020-05-01 20:29 ` [PATCH v4 18/18] objtool: Clean up elf_write() condition Peter Zijlstra
2020-05-06 17:32 ` [PATCH v4 00/18] Add static_call() Josh Poimboeuf
2020-05-06 18:05 ` Peter Zijlstra
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