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From: Masami Hiramatsu <mhiramat@kernel.org>
To: Ingo Molnar <mingo@kernel.org>, David Woodhouse <dwmw@amazon.co.uk>
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
	linux-kernel@vger.kernel.org, Andi Kleen <ak@linux.intel.com>,
	Greg Kroah-Hartman <gregkh@linux-foundation.org>,
	Arjan van de Ven <arjan@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H . Peter Anvin" <hpa@zytor.com>
Subject: [PATCH v2 tip/master 1/3] retpoline: Introduce start/end markers of indirect thunk
Date: Fri, 19 Jan 2018 01:14:21 +0900
Message-ID: <151629206178.10241.6828804696410044771.stgit@devbox> (raw)
In-Reply-To: <151629203720.10241.17490679760505352230.stgit@devbox>

Introduce start/end markers of __x86_indirect_thunk_* functions.
To make it easy, consolidate .text.__x86.indirect_thunk.* sections
to one .text.__x86.indirect_thunk section and put it in the
end of kernel text section and adds __indirect_thunk_start/end
so that other subsystem (e.g. kprobes) can identify it.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
  Changes in v2:
   - Consolidate .text.__x86.indirect_thunk.* sections to
     one .text.__x86.indirect_thunk section. (Thanks David!)
---
 arch/x86/include/asm/nospec-branch.h |    3 +++
 arch/x86/kernel/vmlinux.lds.S        |    6 ++++++
 arch/x86/lib/retpoline.S             |    2 +-
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 7b45d8424150..19ba5ad19c65 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -194,6 +194,9 @@ enum spectre_v2_mitigation {
 	SPECTRE_V2_IBRS,
 };
 
+extern char __indirect_thunk_start[];
+extern char __indirect_thunk_end[];
+
 /*
  * On VMEXIT we must ensure that no RSB predictions learned in the guest
  * can be followed in the host, by overwriting the RSB completely. Both
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 1e413a9326aa..9b138a06c1a4 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -124,6 +124,12 @@ SECTIONS
 		ASSERT(. - _entry_trampoline == PAGE_SIZE, "entry trampoline is too big");
 #endif
 
+#ifdef CONFIG_RETPOLINE
+		__indirect_thunk_start = .;
+		*(.text.__x86.indirect_thunk)
+		__indirect_thunk_end = .;
+#endif
+
 		/* End of text section */
 		_etext = .;
 	} :text = 0x9090
diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S
index cb45c6cb465f..d3415dc30f82 100644
--- a/arch/x86/lib/retpoline.S
+++ b/arch/x86/lib/retpoline.S
@@ -9,7 +9,7 @@
 #include <asm/nospec-branch.h>
 
 .macro THUNK reg
-	.section .text.__x86.indirect_thunk.\reg
+	.section .text.__x86.indirect_thunk
 
 ENTRY(__x86_indirect_thunk_\reg)
 	CFI_STARTPROC

  reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-18 16:13 [PATCH v2 tip/master 0/3] kprobes/x86: retpoline: Fix kprobes for retpoline Masami Hiramatsu
2018-01-18 16:14 ` Masami Hiramatsu [this message]
2018-01-19 15:47   ` [tip:x86/pti] retpoline: Introduce start/end markers of indirect thunk tip-bot for Masami Hiramatsu
2018-01-18 16:14 ` [PATCH v2 tip/master 2/3] kprobes/x86: Blacklist indirect thunk functions for kprobes Masami Hiramatsu
2018-01-19 15:47   ` [tip:x86/pti] " tip-bot for Masami Hiramatsu
2018-01-18 16:15 ` [PATCH v2 tip/master 3/3] kprobes/x86: Disable optimizing on the function jumps to indirect thunk Masami Hiramatsu
2018-01-19 15:48   ` [tip:x86/pti] " tip-bot for Masami Hiramatsu
2018-01-19  9:03 ` [PATCH v2 tip/master 0/3] kprobes/x86: retpoline: Fix kprobes for retpoline David Woodhouse

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