From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
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@xxxxxxxxxx>
Acked-by: Florent Revest <revest@xxxxxxxxxxxx>
---
Changes in v8:
- Add the reason why this required in changelog.
Changes from previous series: NOTHING, just forward ported.
---
arch/arm64/include/asm/ftrace.h | 11 +++++++++++
include/linux/ftrace.h | 17 +++++++++++++++++
2 files changed, 28 insertions(+)
diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index ac82dc43a57d..aab2b7a0f78c 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -143,6 +143,17 @@ ftrace_regs_get_frame_pointer(const struct ftrace_regs *fregs)
return fregs->fp;
}
+static __always_inline struct pt_regs *
+ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)
+{
+ memcpy(regs->regs, fregs->regs, sizeof(u64) * 9);
+ regs->sp = fregs->sp;
+ regs->pc = fregs->pc;
+ regs->regs[29] = fregs->fp;
+ regs->regs[30] = fregs->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/include/linux/ftrace.h b/include/linux/ftrace.h
index ff2966a1b529..914f451b0d69 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -177,6 +177,23 @@ 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_PT_REGS_TO_FTRACE_REGS_CAST)
+
+static __always_inline struct pt_regs *
+ftrace_partial_regs(struct ftrace_regs *fregs, struct pt_regs *regs)
+{
+ /*
+ * If CONFIG_HAVE_PT_REGS_TO_FTRACE_REGS_CAST=y, ftrace_regs memory
+ * layout is the same as 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 &fregs->regs;
+}
+
+#endif /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS || CONFIG_HAVE_PT_REGS_TO_FTRACE_REGS_CAST */
+
/*
* 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.
