From: Dmitry Safonov <dima@arista.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org,
Dmitry Safonov <0x7f454c46@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Dmitry Safonov <dima@arista.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Ingo Molnar <mingo@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH-4.19-stable 1/2] x86/stackframe: Move ENCODE_FRAME_POINTER to asm/frame.h
Date: Mon, 10 Feb 2020 14:05:42 +0000 [thread overview]
Message-ID: <20200210140543.79641-2-dima@arista.com> (raw)
In-Reply-To: <20200210140543.79641-1-dima@arista.com>
From: Peter Zijlstra <peterz@infradead.org>
[ Upstream commit a9b3c6998d4a7d53a787cf4d0fd4a4c11239e517 ]
In preparation for wider use, move the ENCODE_FRAME_POINTER macros to
a common header and provide inline asm versions.
These macros are used to encode a pt_regs frame for the unwinder; see
unwind_frame.c:decode_frame_pointer().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
arch/x86/entry/calling.h | 15 -----------
arch/x86/entry/entry_32.S | 16 ------------
arch/x86/include/asm/frame.h | 49 ++++++++++++++++++++++++++++++++++++
3 files changed, 49 insertions(+), 31 deletions(-)
diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h
index 578b5455334f..31fbb4a7d9f6 100644
--- a/arch/x86/entry/calling.h
+++ b/arch/x86/entry/calling.h
@@ -172,21 +172,6 @@ For 32-bit we have the following conventions - kernel is built with
.endif
.endm
-/*
- * This is a sneaky trick to help the unwinder find pt_regs on the stack. The
- * frame pointer is replaced with an encoded pointer to pt_regs. The encoding
- * is just setting the LSB, which makes it an invalid stack address and is also
- * a signal to the unwinder that it's a pt_regs pointer in disguise.
- *
- * NOTE: This macro must be used *after* PUSH_AND_CLEAR_REGS because it corrupts
- * the original rbp.
- */
-.macro ENCODE_FRAME_POINTER ptregs_offset=0
-#ifdef CONFIG_FRAME_POINTER
- leaq 1+\ptregs_offset(%rsp), %rbp
-#endif
-.endm
-
#ifdef CONFIG_PAGE_TABLE_ISOLATION
/*
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 8059d4fd915c..d07432062ee6 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -245,22 +245,6 @@
.Lend_\@:
.endm
-/*
- * This is a sneaky trick to help the unwinder find pt_regs on the stack. The
- * frame pointer is replaced with an encoded pointer to pt_regs. The encoding
- * is just clearing the MSB, which makes it an invalid stack address and is also
- * a signal to the unwinder that it's a pt_regs pointer in disguise.
- *
- * NOTE: This macro must be used *after* SAVE_ALL because it corrupts the
- * original rbp.
- */
-.macro ENCODE_FRAME_POINTER
-#ifdef CONFIG_FRAME_POINTER
- mov %esp, %ebp
- andl $0x7fffffff, %ebp
-#endif
-.endm
-
.macro RESTORE_INT_REGS
popl %ebx
popl %ecx
diff --git a/arch/x86/include/asm/frame.h b/arch/x86/include/asm/frame.h
index 5cbce6fbb534..296b346184b2 100644
--- a/arch/x86/include/asm/frame.h
+++ b/arch/x86/include/asm/frame.h
@@ -22,6 +22,35 @@
pop %_ASM_BP
.endm
+#ifdef CONFIG_X86_64
+/*
+ * This is a sneaky trick to help the unwinder find pt_regs on the stack. The
+ * frame pointer is replaced with an encoded pointer to pt_regs. The encoding
+ * is just setting the LSB, which makes it an invalid stack address and is also
+ * a signal to the unwinder that it's a pt_regs pointer in disguise.
+ *
+ * NOTE: This macro must be used *after* PUSH_AND_CLEAR_REGS because it corrupts
+ * the original rbp.
+ */
+.macro ENCODE_FRAME_POINTER ptregs_offset=0
+ leaq 1+\ptregs_offset(%rsp), %rbp
+.endm
+#else /* !CONFIG_X86_64 */
+/*
+ * This is a sneaky trick to help the unwinder find pt_regs on the stack. The
+ * frame pointer is replaced with an encoded pointer to pt_regs. The encoding
+ * is just clearing the MSB, which makes it an invalid stack address and is also
+ * a signal to the unwinder that it's a pt_regs pointer in disguise.
+ *
+ * NOTE: This macro must be used *after* SAVE_ALL because it corrupts the
+ * original ebp.
+ */
+.macro ENCODE_FRAME_POINTER
+ mov %esp, %ebp
+ andl $0x7fffffff, %ebp
+.endm
+#endif /* CONFIG_X86_64 */
+
#else /* !__ASSEMBLY__ */
#define FRAME_BEGIN \
@@ -30,12 +59,32 @@
#define FRAME_END "pop %" _ASM_BP "\n"
+#ifdef CONFIG_X86_64
+#define ENCODE_FRAME_POINTER \
+ "lea 1(%rsp), %rbp\n\t"
+#else /* !CONFIG_X86_64 */
+#define ENCODE_FRAME_POINTER \
+ "movl %esp, %ebp\n\t" \
+ "andl $0x7fffffff, %ebp\n\t"
+#endif /* CONFIG_X86_64 */
+
#endif /* __ASSEMBLY__ */
#define FRAME_OFFSET __ASM_SEL(4, 8)
#else /* !CONFIG_FRAME_POINTER */
+#ifdef __ASSEMBLY__
+
+.macro ENCODE_FRAME_POINTER ptregs_offset=0
+.endm
+
+#else /* !__ASSEMBLY */
+
+#define ENCODE_FRAME_POINTER
+
+#endif
+
#define FRAME_BEGIN
#define FRAME_END
#define FRAME_OFFSET 0
--
2.25.0
next prev parent reply other threads:[~2020-02-10 14:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-10 14:05 [PATCH-4.19-stable 0/2] Backport ENCODE_FRAME_POINTER hint Dmitry Safonov
2020-02-10 14:05 ` Dmitry Safonov [this message]
2020-02-10 14:05 ` [PATCH-4.19-stable 2/2] x86/stackframe, x86/ftrace: Add pt_regs frame annotations Dmitry Safonov
2020-02-13 15:01 ` [PATCH-4.19-stable 0/2] Backport ENCODE_FRAME_POINTER hint Greg Kroah-Hartman
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