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Subject[PATCH-4.19-stable 2/2] x86/stackframe, x86/ftrace: Add pt_regs frame annotations
Date
From: Peter Zijlstra <peterz@infradead.org>

[ Upstream commit ea1ed38dba64b64a245ab8ca1406269d17b99485 ]

When CONFIG_FRAME_POINTER, we should mark pt_regs frames.

Fixes user-visible warning for unwinder (i.e, ftrace's stack tracer):
> WARNING: kernel stack frame pointer at 00000000bceb5183 in Coronavirus:3282 has bad value (null)
> unwind stack type:0 next_sp: (null) mask:0x2 graph_idx:0
> 000000009630aa47: ffffc9000126fdb0 (0xffffc9000126fdb0)
> 0000000020360f53: ffffffff81038e33 (__save_stack_trace+0xcb/0xee)
> 00000000675081f2: 0000000000000000 ...
> 0000000043198fe7: ffffc9000126c000 (0xffffc9000126c000)
> 0000000008a46231: ffffc90001270000 (0xffffc90001270000)
[..]

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>
[4.19 backport; added user-visible changelog]
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
arch/x86/kernel/ftrace_32.S | 3 +++
arch/x86/kernel/ftrace_64.S | 3 +++
2 files changed, 6 insertions(+)

diff --git a/arch/x86/kernel/ftrace_32.S b/arch/x86/kernel/ftrace_32.S
index 4c8440de3355..83f18e829ac7 100644
--- a/arch/x86/kernel/ftrace_32.S
+++ b/arch/x86/kernel/ftrace_32.S
@@ -9,6 +9,7 @@
#include <asm/export.h>
#include <asm/ftrace.h>
#include <asm/nospec-branch.h>
+#include <asm/frame.h>

#ifdef CC_USING_FENTRY
# define function_hook __fentry__
@@ -131,6 +132,8 @@ ENTRY(ftrace_regs_caller)
pushl %ecx
pushl %ebx

+ ENCODE_FRAME_POINTER
+
movl 12*4(%esp), %eax /* Load ip (1st parameter) */
subl $MCOUNT_INSN_SIZE, %eax /* Adjust ip */
#ifdef CC_USING_FENTRY
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S
index 75f2b36b41a6..24b9abf718e8 100644
--- a/arch/x86/kernel/ftrace_64.S
+++ b/arch/x86/kernel/ftrace_64.S
@@ -9,6 +9,7 @@
#include <asm/export.h>
#include <asm/nospec-branch.h>
#include <asm/unwind_hints.h>
+#include <asm/frame.h>

.code64
.section .entry.text, "ax"
@@ -222,6 +223,8 @@ GLOBAL(ftrace_regs_caller_op_ptr)
leaq MCOUNT_REG_SIZE+8*2(%rsp), %rcx
movq %rcx, RSP(%rsp)

+ ENCODE_FRAME_POINTER
+
/* regs go into 4th parameter */
leaq (%rsp), %rcx

--
2.25.0
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