linux-kernel - [PATCH 3/3] riscv: pack rv64 thread

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Message-ID: <20250722160556.2216925-5-rkrcmar@ventanamicro.com>
Date: Tue, 22 Jul 2025 18:05:57 +0200
From: Radim Krčmář <rkrcmar@...tanamicro.com>
To: linux-riscv@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Alexandre Ghiti <alex@...ti.fr>,
	Deepak Gupta <debug@...osinc.com>
Subject: [PATCH 3/3] riscv: pack rv64 thread_info better

On rv64, preempt_count and cpu were both 32-bit followed by 64-bit, so
placing one in the hole saves 8 bytes in the struct.

Signed-off-by: Radim Krčmář <rkrcmar@...tanamicro.com>
---
 arch/riscv/include/asm/thread_info.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/thread_info.h b/arch/riscv/include/asm/thread_info.h
index f5916a70879a..c267d6bd838e 100644
--- a/arch/riscv/include/asm/thread_info.h
+++ b/arch/riscv/include/asm/thread_info.h
@@ -53,6 +53,7 @@
 struct thread_info {
 	unsigned long		flags;		/* low level flags */
 	int                     preempt_count;  /* 0=>preemptible, <0=>BUG */
+	int			cpu;
 	/*
 	 * These stack pointers are overwritten on every system call or
 	 * exception.  SP is also saved to the stack it can be recovered when
@@ -60,7 +61,6 @@ struct thread_info {
 	 */
 	long			kernel_sp;	/* Kernel stack pointer */
 	long			user_sp;	/* User stack pointer */
-	int			cpu;
 	unsigned long		syscall_work;	/* SYSCALL_WORK_ flags */
 #ifdef CONFIG_SHADOW_CALL_STACK
 	void			*scs_base;
-- 
2.50.0