tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs

Add ftrace_partial_regs() which converts the ftrace_regs to pt_regs.
This is for the eBPF which needs this to keep the same pt_regs interface
to access registers.
Thus when replacing the pt_regs with ftrace_regs in fprobes (which is
used by kprobe_multi eBPF event), this will be used.

If the architecture defines its own ftrace_regs, this copies partial
registers to pt_regs and returns it. If not, ftrace_regs is the same as
pt_regs and ftrace_partial_regs() will return ftrace_regs::regs.

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Florent Revest <revest@chromium.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf <bpf@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Link: https://lore.kernel.org/173518996761.391279.4987911298206448122.stgit@devnote2
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index b5fa57b61378e9b39fd972ad1cdbef5714b83d58..09210f853f12d762713d53d310684a543b4a0669 100644 (file)
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -135,6 +135,19 @@ ftrace_regs_get_frame_pointer(const struct ftrace_regs *fregs)
        return arch_ftrace_regs(fregs)->fp;
 }
 
+static __always_inline struct pt_regs *
+ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)
+{
+       struct __arch_ftrace_regs *afregs = arch_ftrace_regs(fregs);
+
+       memcpy(regs->regs, afregs->regs, sizeof(afregs->regs));
+       regs->sp = afregs->sp;
+       regs->pc = afregs->pc;
+       regs->regs[29] = afregs->fp;
+       regs->regs[30] = afregs->lr;
+       return regs;
+}
+
 int ftrace_regs_query_register_offset(const char *name);
 
 int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);

diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
index 9372f8d7036f87d01eea24ba2015f22ef54ac6e1..7064a530794b6ad9480cdc60bd27abf65c0ed146 100644 (file)
--- a/arch/riscv/include/asm/ftrace.h
+++ b/arch/riscv/include/asm/ftrace.h
@@ -197,6 +197,20 @@ static __always_inline void ftrace_override_function_with_return(struct ftrace_r
        arch_ftrace_regs(fregs)->epc = arch_ftrace_regs(fregs)->ra;
 }
 
+static __always_inline struct pt_regs *
+ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)
+{
+       struct __arch_ftrace_regs *afregs = arch_ftrace_regs(fregs);
+
+       memcpy(&regs->a0, afregs->args, sizeof(afregs->args));
+       regs->epc = afregs->epc;
+       regs->ra = afregs->ra;
+       regs->sp = afregs->sp;
+       regs->s0 = afregs->s0;
+       regs->t1 = afregs->t1;
+       return regs;
+}
+
 int ftrace_regs_query_register_offset(const char *name);
 
 void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index bf8bb6c105533b0cff72d00d4ddc87ae4a1a83e1..ad2b46e1d5b02d46088698d01af9fea5ed6c423b 100644 (file)
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -190,6 +190,23 @@ static __always_inline struct pt_regs *ftrace_get_regs(struct ftrace_regs *fregs
        return arch_ftrace_get_regs(fregs);
 }
 
+#if !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) || \
+       defined(CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS)
+
+static __always_inline struct pt_regs *
+ftrace_partial_regs(struct ftrace_regs *fregs, struct pt_regs *regs)
+{
+       /*
+        * If CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS=y, ftrace_regs memory
+        * layout is including pt_regs. So always returns that address.
+        * Since arch_ftrace_get_regs() will check some members and may return
+        * NULL, we can not use it.
+        */
+       return &arch_ftrace_regs(fregs)->regs;
+}
+
+#endif /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS || CONFIG_HAVE_FTRACE_REGS_HAVING_PT_REGS */
+
 /*
  * 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.