[PATCH v20 07/19] tracing: Add ftrace_fill_perf_regs() for perf event

["Masami Hiramatsu (Google)" <mhiramat@kernel.org>]

From: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Add ftrace_fill_perf_regs() which should be compatible with the
perf_fetch_caller_regs(). In other words, the pt_regs returned from the
ftrace_fill_perf_regs() must satisfy 'user_mode(regs) == false' and can be
used for stack tracing.

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>

---
  Changes in v16:
   - Fix s390 to clear psw.mask according to Heiko's suggestion.
---
 arch/arm64/include/asm/ftrace.h   |    7 +++++++
 arch/powerpc/include/asm/ftrace.h |    7 +++++++
 arch/s390/include/asm/ftrace.h    |    6 ++++++
 arch/x86/include/asm/ftrace.h     |    7 +++++++
 include/linux/ftrace.h            |   31 +++++++++++++++++++++++++++++++
 5 files changed, 58 insertions(+)

diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index 09210f853f12..10e56522122a 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -148,6 +148,13 @@ ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)
 	return regs;
 }
 
+#define arch_ftrace_fill_perf_regs(fregs, _regs) do {		\
+		(_regs)->pc = arch_ftrace_regs(fregs)->pc;			\
+		(_regs)->regs[29] = arch_ftrace_regs(fregs)->fp;		\
+		(_regs)->sp = arch_ftrace_regs(fregs)->sp;			\
+		(_regs)->pstate = PSR_MODE_EL1h;		\
+	} while (0)
+
 int ftrace_regs_query_register_offset(const char *name);
 
 int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
index db481b336bca..fe181bafdca4 100644
--- a/arch/powerpc/include/asm/ftrace.h
+++ b/arch/powerpc/include/asm/ftrace.h
@@ -43,6 +43,13 @@ static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs *
 	return arch_ftrace_regs(fregs)->regs.msr ? &arch_ftrace_regs(fregs)->regs : NULL;
 }
 
+#define arch_ftrace_fill_perf_regs(fregs, _regs) do {		\
+		(_regs)->result = 0;				\
+		(_regs)->nip = arch_ftrace_regs(fregs)->regs.nip;		\
+		(_regs)->gpr[1] = arch_ftrace_regs(fregs)->regs.gpr[1];		\
+		asm volatile("mfmsr %0" : "=r" ((_regs)->msr));	\
+	} while (0)
+
 static __always_inline void
 ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,
 				    unsigned long ip)
diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h
index 5c94c1fc1bc1..5b7cb49c41ee 100644
--- a/arch/s390/include/asm/ftrace.h
+++ b/arch/s390/include/asm/ftrace.h
@@ -76,6 +76,12 @@ ftrace_regs_get_frame_pointer(struct ftrace_regs *fregs)
 	return ftrace_regs_get_stack_pointer(fregs);
 }
 
+#define arch_ftrace_fill_perf_regs(fregs, _regs)	 do {		\
+		(_regs)->psw.mask = 0;					\
+		(_regs)->psw.addr = arch_ftrace_regs(fregs)->regs.psw.addr;		\
+		(_regs)->gprs[15] = arch_ftrace_regs(fregs)->regs.gprs[15];		\
+	} while (0)
+
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
 /*
  * When an ftrace registered caller is tracing a function that is
diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index d61407c680c2..7e06f8c7937a 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -47,6 +47,13 @@ arch_ftrace_get_regs(struct ftrace_regs *fregs)
 	return &arch_ftrace_regs(fregs)->regs;
 }
 
+#define arch_ftrace_fill_perf_regs(fregs, _regs) do {	\
+		(_regs)->ip = arch_ftrace_regs(fregs)->regs.ip;		\
+		(_regs)->sp = arch_ftrace_regs(fregs)->regs.sp;		\
+		(_regs)->cs = __KERNEL_CS;		\
+		(_regs)->flags = 0;			\
+	} while (0)
+
 #define ftrace_regs_set_instruction_pointer(fregs, _ip)	\
 	do { arch_ftrace_regs(fregs)->regs.ip = (_ip); } while (0)
 
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index ad2b46e1d5b0..6d29c640697c 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -207,6 +207,37 @@ ftrace_partial_regs(struct ftrace_regs *fregs, struct pt_regs *regs)
 
 #endif /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS || CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS */
 
+#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
+
+/*
+ * Please define arch dependent pt_regs which compatible to the
+ * perf_arch_fetch_caller_regs() but based on ftrace_regs.
+ * This requires
+ *   - user_mode(_regs) returns false (always kernel mode).
+ *   - able to use the _regs for stack trace.
+ */
+#ifndef arch_ftrace_fill_perf_regs
+/* As same as perf_arch_fetch_caller_regs(), do nothing by default */
+#define arch_ftrace_fill_perf_regs(fregs, _regs) do {} while (0)
+#endif
+
+static __always_inline struct pt_regs *
+ftrace_fill_perf_regs(struct ftrace_regs *fregs, struct pt_regs *regs)
+{
+	arch_ftrace_fill_perf_regs(fregs, regs);
+	return regs;
+}
+
+#else /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
+
+static __always_inline struct pt_regs *
+ftrace_fill_perf_regs(struct ftrace_regs *fregs, struct pt_regs *regs)
+{
+	return &arch_ftrace_regs(fregs)->regs;
+}
+
+#endif
+
 /*
  * When true, the ftrace_regs_{get,set}_*() functions may be used on fregs.
  * Note: this can be true even when ftrace_get_regs() cannot provide a pt_regs.