linux-kernel - [PATCH v2 7/7] riscv: rely on core code to keep thread

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Date:   Thu, 30 Sep 2021 14:58:13 +0200
From:   Ard Biesheuvel <ardb@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     Ard Biesheuvel <ardb@...nel.org>,
        Keith Packard <keithpac@...zon.com>,
        Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Paul Mackerras <paulus@...ba.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>,
        Mark Rutland <mark.rutland@....com>
Subject: [PATCH v2 7/7] riscv: rely on core code to keep thread_info::cpu updated

Now that the core code switched back to using thread_info::cpu to keep
a task's CPU number, we no longer need to keep it in sync explicitly. So
just drop the code that does this.

Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
Acked-by: Palmer Dabbelt <palmerdabbelt@...gle.com>
Acked-by: Mark Rutland <mark.rutland@....com>
---
 arch/riscv/kernel/asm-offsets.c | 1 -
 arch/riscv/kernel/entry.S       | 5 -----
 arch/riscv/kernel/head.S        | 1 -
 3 files changed, 7 deletions(-)

diff --git a/arch/riscv/kernel/asm-offsets.c b/arch/riscv/kernel/asm-offsets.c
index 90f8ce64fa6f..478d9f02dab5 100644
--- a/arch/riscv/kernel/asm-offsets.c
+++ b/arch/riscv/kernel/asm-offsets.c
@@ -33,7 +33,6 @@ void asm_offsets(void)
 	OFFSET(TASK_TI_PREEMPT_COUNT, task_struct, thread_info.preempt_count);
 	OFFSET(TASK_TI_KERNEL_SP, task_struct, thread_info.kernel_sp);
 	OFFSET(TASK_TI_USER_SP, task_struct, thread_info.user_sp);
-	OFFSET(TASK_TI_CPU, task_struct, thread_info.cpu);
 
 	OFFSET(TASK_THREAD_F0,  task_struct, thread.fstate.f[0]);
 	OFFSET(TASK_THREAD_F1,  task_struct, thread.fstate.f[1]);
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index 98f502654edd..459eb1714353 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -544,11 +544,6 @@ ENTRY(__switch_to)
 	REG_L s9,  TASK_THREAD_S9_RA(a4)
 	REG_L s10, TASK_THREAD_S10_RA(a4)
 	REG_L s11, TASK_THREAD_S11_RA(a4)
-	/* Swap the CPU entry around. */
-	lw a3, TASK_TI_CPU(a0)
-	lw a4, TASK_TI_CPU(a1)
-	sw a3, TASK_TI_CPU(a1)
-	sw a4, TASK_TI_CPU(a0)
 	/* The offset of thread_info in task_struct is zero. */
 	move tp, a1
 	ret
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index fce5184b22c3..d5ec30ef6f5d 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -317,7 +317,6 @@ clear_bss_done:
 	call setup_trap_vector
 	/* Restore C environment */
 	la tp, init_task
-	sw zero, TASK_TI_CPU(tp)
 	la sp, init_thread_union + THREAD_SIZE
 
 #ifdef CONFIG_KASAN
-- 
2.30.2