From: Josh Poimboeuf <jpoimboe@redhat.com>
To: x86@kernel.org
Cc: linux-kernel@vger.kernel.org,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Andy Lutomirski <luto@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Jason Baron <jbaron@akamai.com>, Jiri Kosina <jkosina@suse.cz>,
David Laight <David.Laight@ACULAB.COM>,
Borislav Petkov <bp@alien8.de>, Julia Cartwright <julia@ni.com>,
Jessica Yu <jeyu@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>
Subject: [PATCH v2 3/4] x86/static_call: Add out-of-line static call implementation
Date: Mon, 26 Nov 2018 07:54:59 -0600 [thread overview]
Message-ID: <00b08f2194e80241decbf206624b6580b9b8855b.1543200841.git.jpoimboe@redhat.com> (raw)
In-Reply-To: <cover.1543200841.git.jpoimboe@redhat.com>
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>
---
arch/x86/Kconfig | 1 +
arch/x86/include/asm/static_call.h | 28 ++++++++++++++++
arch/x86/kernel/Makefile | 1 +
arch/x86/kernel/static_call.c | 54 ++++++++++++++++++++++++++++++
include/linux/static_call.h | 2 +-
5 files changed, 85 insertions(+), 1 deletion(-)
create mode 100644 arch/x86/include/asm/static_call.h
create mode 100644 arch/x86/kernel/static_call.c
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index b5286ad2a982..a2a10e0ce248 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -189,6 +189,7 @@ 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_OUTLINE
select HAVE_RSEQ
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_UNSTABLE_SCHED_CLOCK
diff --git a/arch/x86/include/asm/static_call.h b/arch/x86/include/asm/static_call.h
new file mode 100644
index 000000000000..6e9ad5969ec2
--- /dev/null
+++ b/arch/x86/include/asm/static_call.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_STATIC_CALL_H
+#define _ASM_STATIC_CALL_H
+
+/*
+ * Manually construct a 5-byte direct JMP to prevent the assembler from
+ * optimizing it into a 2-byte JMP.
+ */
+#define __ARCH_STATIC_CALL_JMP_LABEL(key) ".L" __stringify(key ## _after_jmp)
+#define __ARCH_STATIC_CALL_TRAMP_JMP(key, func) \
+ ".byte 0xe9 \n" \
+ ".long " #func " - " __ARCH_STATIC_CALL_JMP_LABEL(key) "\n" \
+ __ARCH_STATIC_CALL_JMP_LABEL(key) ":"
+
+/*
+ * This is a permanent trampoline which does a direct jump to the function.
+ * The direct jump get patched by static_call_update().
+ */
+#define ARCH_DEFINE_STATIC_CALL_TRAMP(key, func) \
+ asm(".pushsection .text, \"ax\" \n" \
+ ".align 4 \n" \
+ ".globl " STATIC_CALL_TRAMP_STR(key) " \n" \
+ ".type " STATIC_CALL_TRAMP_STR(key) ", @function \n" \
+ STATIC_CALL_TRAMP_STR(key) ": \n" \
+ __ARCH_STATIC_CALL_TRAMP_JMP(key, func) " \n" \
+ ".popsection \n")
+
+#endif /* _ASM_STATIC_CALL_H */
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 8824d01c0c35..82acc8a28429 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -62,6 +62,7 @@ obj-y += tsc.o tsc_msr.o io_delay.o rtc.o
obj-y += pci-iommu_table.o
obj-y += resource.o
obj-y += irqflags.o
+obj-y += static_call.o
obj-y += process.o
obj-y += fpu/
diff --git a/arch/x86/kernel/static_call.c b/arch/x86/kernel/static_call.c
new file mode 100644
index 000000000000..8026d176f25c
--- /dev/null
+++ b/arch/x86/kernel/static_call.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/static_call.h>
+#include <linux/memory.h>
+#include <linux/bug.h>
+#include <asm/text-patching.h>
+#include <asm/nospec-branch.h>
+
+#define CALL_INSN_SIZE 5
+
+void static_call_bp_handler(void);
+void *bp_handler_dest;
+
+asm(".pushsection .text, \"ax\" \n"
+ ".globl static_call_bp_handler \n"
+ ".type static_call_bp_handler, @function \n"
+ "static_call_bp_handler: \n"
+ "ANNOTATE_RETPOLINE_SAFE \n"
+ "jmp *bp_handler_dest \n"
+ ".popsection \n");
+
+void arch_static_call_transform(void *site, void *tramp, void *func)
+{
+ s32 dest_relative;
+ unsigned long insn;
+ unsigned char insn_opcode;
+ unsigned char opcodes[CALL_INSN_SIZE];
+
+ insn = (unsigned long)tramp;
+
+ mutex_lock(&text_mutex);
+
+ insn_opcode = *(unsigned char *)insn;
+ if (insn_opcode != 0xe8 && insn_opcode != 0xe9) {
+ WARN_ONCE(1, "unexpected static call insn opcode 0x%x at %pS",
+ insn_opcode, (void *)insn);
+ goto done;
+ }
+
+ dest_relative = (long)(func) - (long)(insn + CALL_INSN_SIZE);
+
+ opcodes[0] = insn_opcode;
+ memcpy(&opcodes[1], &dest_relative, CALL_INSN_SIZE - 1);
+
+ /* Set up the variable for the breakpoint handler: */
+ bp_handler_dest = func;
+
+ /* Patch the call site: */
+ text_poke_bp((void *)insn, opcodes, CALL_INSN_SIZE,
+ static_call_bp_handler);
+
+done:
+ mutex_unlock(&text_mutex);
+}
+EXPORT_SYMBOL_GPL(arch_static_call_transform);
diff --git a/include/linux/static_call.h b/include/linux/static_call.h
index c8d0da1ef6b2..651f4d784377 100644
--- a/include/linux/static_call.h
+++ b/include/linux/static_call.h
@@ -149,7 +149,7 @@ struct static_call_key {
.func = _func, \
.tramp = STATIC_CALL_TRAMP(key), \
}; \
- ARCH_DEFINE_STATIC_CALL_TRAMP(key, func)
+ ARCH_DEFINE_STATIC_CALL_TRAMP(key, _func)
#define static_call(key, args...) STATIC_CALL_TRAMP(key)(args)
--
2.17.2
next prev parent reply other threads:[~2018-11-26 13:55 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 ` Josh Poimboeuf [this message]
2018-11-26 15:43 ` [PATCH v2 3/4] x86/static_call: Add out-of-line static call implementation 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
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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