[RFC PATCH 4/5] ftrace: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs

From: Masami Hiramatsu (Google)
Date: Sat Aug 05 2023 - 10:58:57 EST


From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>

Add ftrace_partial_regs() which converts the ftrace_regas to pt_regs.
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>
---
arch/arm64/include/asm/ftrace.h | 11 +++++++++++
include/linux/ftrace.h | 11 +++++++++++
2 files changed, 22 insertions(+)

diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index ab158196480c..b108cd6718cf 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -137,6 +137,17 @@ ftrace_override_function_with_return(struct ftrace_regs *fregs)
fregs->pc = fregs->lr;
}

+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) * 10);
+ regs->sp = fregs->sp;
+ regs->pc = fregs->pc;
+ regs->x[29] = fregs->fp;
+ regs->x[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 ce156c7704ee..f4fbc493aceb 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -139,6 +139,17 @@ 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_COMPAT_FTRACE_REGS)
+
+static __always_inline struct pt_regs *
+ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)
+{
+ return arch_ftrace_get_regs((struct ftrace_regs *)fregs);
+}
+
+#endif /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS || CONFIG_HAVE_PT_REGS_COMPAT_FTRACE_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.