FAILED: patch "[PATCH] riscv: ftrace: Fixup panic by disabling preemption" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 8547649981e6631328cd64f583667501ae385531
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '[email protected]' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

8547649981e6 ("riscv: ftrace: Fixup panic by disabling preemption") f32b4b467ebd ("RISC-V: enable dynamic ftrace for RV32I")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 8547649981e6631328cd64f583667501ae385531 Mon Sep 17 00:00:00 2001
From: Andy Chiu <[email protected]>
Date: Thu, 12 Jan 2023 04:05:57 -0500
Subject: [PATCH] riscv: ftrace: Fixup panic by disabling preemption

In RISCV, we must use an AUIPC + JALR pair to encode an immediate, forming a jump that jumps to an address over 4K. This may cause errors if we want to enable kernel preemption and remove dependency from patching code with stop_machine(). For example, if a task was switched out on auipc. And, if we changed the ftrace function before it was switched back, then it would jump to an address that has updated 11:0 bits mixing with previous XLEN:12 part.

p: patched area performed by dynamic ftrace
ftrace_prologue:

p|      REG_S   ra, -SZREG(sp)
p|      auipc   ra, 0x? ------------> preempted
					...
				change ftrace function
					...
p|      jalr    -?(ra) <------------- switched back
p|      REG_L   ra, -SZREG(sp)

func:
xxx
ret

index e2b656043abf..ee0d39b26794 100644
@@ -138,7 +138,7 @@ config RISCV
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
 	select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
 	select HAVE_FUNCTION_GRAPH_TRACER
-	select HAVE_FUNCTION_TRACER if !XIP_KERNEL
+	select HAVE_FUNCTION_TRACER if !XIP_KERNEL && !PREEMPTION
 
 config ARCH_MMAP_RND_BITS_MIN
 	default 18 if 64BIT