linux-kernel - [PATCH 5/7] powerpc, arm64: Mark __switch_to() as _

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Date:   Fri, 22 Oct 2021 17:09:38 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     keescook@...omium.org, x86@...nel.org
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        juri.lelli@...hat.com, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
        mgorman@...e.de, bristot@...hat.com, akpm@...ux-foundation.org,
        mark.rutland@....com, zhengqi.arch@...edance.com,
        linux@...linux.org.uk, catalin.marinas@....com, will@...nel.org,
        mpe@...erman.id.au, paul.walmsley@...ive.com, palmer@...belt.com,
        hca@...ux.ibm.com, gor@...ux.ibm.com, borntraeger@...ibm.com,
        linux-arch@...r.kernel.org, ardb@...nel.org
Subject: [PATCH 5/7] powerpc, arm64: Mark __switch_to() as __sched

Unlike most of the other architectures, PowerPC and ARM64 have
__switch_to() as a C function which remains on the stack. Their
respective __get_wchan() skips one stack frame unconditionally,
without testing is_sched_functions().

Mark them __sched such that we can forgo that special case.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/arm64/kernel/process.c   |    4 ++--
 arch/powerpc/kernel/process.c |    4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -490,8 +490,8 @@ void update_sctlr_el1(u64 sctlr)
 /*
  * Thread switching.
  */
-__notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev,
-				struct task_struct *next)
+__notrace_funcgraph __sched
+struct task_struct *__switch_to(struct task_struct *prev, struct task_struct *next)
 {
 	struct task_struct *last;
 
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1201,8 +1201,8 @@ static inline void restore_sprs(struct t
 
 }
 
-struct task_struct *__switch_to(struct task_struct *prev,
-	struct task_struct *new)
+__sched struct task_struct *__switch_to(struct task_struct *prev,
+					struct task_struct *new)
 {
 	struct thread_struct *new_thread, *old_thread;
 	struct task_struct *last;