[PATCH v21 08/20] tracing: Add ftrace_fill_perf_regs() for perf event

Masami Hiramatsu (Google)
2024-12-10T02:10:41Z

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>
Acked-by: Heiko Carstens <hca@linux.ibm.com> # s390
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: 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.