Re: [PATCH v14 08/19] tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Date: 2024-10-01 23:26:22
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On Tue, 17 Sep 2024 11:14:54 +0100 Will Deacon [off-list ref] wrote:
On Sun, Sep 15, 2024 at 05:22:04AM -0400, Steven Rostedt wrote:quoted
On Fri, 13 Sep 2024 00:09:35 +0900 "Masami Hiramatsu (Google)" [off-list ref] wrote:quoted
From: Masami Hiramatsu (Google) <mhiramat@kernel.org> 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 <redacted> --- Changes in v14: - Add riscv change. 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 +++++++++++ arch/riscv/include/asm/ftrace.h | 12 ++++++++++++ include/linux/ftrace.h | 17 +++++++++++++++++ 3 files changed, 40 insertions(+)diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h index dffaab3dd1f1..5cd587afab6d 100644 --- a/arch/arm64/include/asm/ftrace.h +++ b/arch/arm64/include/asm/ftrace.h@@ -132,6 +132,17 @@ 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; +}Ah, I guess this is where we pick up the lr that was set in patch 5.
Yeah, this one also copies the fregs->pc to regs->pc, mainly for bpf.
Acked-by: Will Deacon <will@kernel.org>
Thank you!
Will
-- Masami Hiramatsu (Google) [off-list ref]