From: Masami Hiramatsu (Google) <mhira...@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) <mhira...@kernel.org>
---
  Changes from previous series: NOTHING, just forward ported.
---
 arch/arm64/include/asm/ftrace.h   |    7 +++++++
 arch/powerpc/include/asm/ftrace.h |    7 +++++++
 arch/s390/include/asm/ftrace.h    |    5 +++++
 arch/x86/include/asm/ftrace.h     |    7 +++++++
 include/linux/ftrace.h            |   31 +++++++++++++++++++++++++++++++
 5 files changed, 57 insertions(+)

diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index aab2b7a0f78c..95a8f349f871 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -154,6 +154,13 @@ 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 = (fregs)->pc;                      \
+               (_regs)->regs[29] = (fregs)->fp;                \
+               (_regs)->sp = (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 cfec6c5a47d0..51245fd6b45b 100644
--- a/arch/powerpc/include/asm/ftrace.h
+++ b/arch/powerpc/include/asm/ftrace.h
@@ -44,6 +44,13 @@ static __always_inline struct pt_regs 
*arch_ftrace_get_regs(struct ftrace_regs *
        return fregs->regs.msr ? &fregs->regs : NULL;
 }
 
+#define arch_ftrace_fill_perf_regs(fregs, _regs) do {          \
+               (_regs)->result = 0;                            \
+               (_regs)->nip = (fregs)->regs.nip;               \
+               (_regs)->gpr[1] = (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 9f8cc6d13bec..cb8d60a5fe1d 100644
--- a/arch/s390/include/asm/ftrace.h
+++ b/arch/s390/include/asm/ftrace.h
@@ -89,6 +89,11 @@ ftrace_regs_get_frame_pointer(struct ftrace_regs *fregs)
        return sp[0];   /* return backchain */
 }
 
+#define arch_ftrace_fill_perf_regs(fregs, _regs)        do {           \
+               (_regs)->psw.addr = (fregs)->regs.psw.addr;             \
+               (_regs)->gprs[15] = (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 8d6db2b7d03a..7625887fc49b 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -54,6 +54,13 @@ arch_ftrace_get_regs(struct ftrace_regs *fregs)
        return &fregs->regs;
 }
 
+#define arch_ftrace_fill_perf_regs(fregs, _regs) do {  \
+               (_regs)->ip = (fregs)->regs.ip;         \
+               (_regs)->sp = (fregs)->regs.sp;         \
+               (_regs)->cs = __KERNEL_CS;              \
+               (_regs)->flags = 0;                     \
+       } while (0)
+
 #define ftrace_regs_set_instruction_pointer(fregs, _ip)        \
        do { (fregs)->regs.ip = (_ip); } while (0)
 
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 9cf4c1b8b3f8..71dd25afdb1c 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -194,6 +194,37 @@ ftrace_partial_regs(struct ftrace_regs *fregs, struct 
pt_regs *regs)
 
 #endif /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS || 
CONFIG_HAVE_PT_REGS_TO_FTRACE_REGS_CAST */
 
+#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 &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.


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