linux-kernel - [PATCH] powerpc: Only pad struct pt

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Message-Id: <d536bbc46094f66b24d3017343be25164f232933.1620307840.git.christophe.leroy@csgroup.eu>
Date:   Thu,  6 May 2021 13:30:51 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH] powerpc: Only pad struct pt_regs when needed

If neither KUAP nor PPC64 is selected, there is nothing in the second
union of struct pt_regs, so the alignment padding is waste of memory.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/include/asm/ptrace.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index 9c9ab2746168..4fd3a3bd5272 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -47,7 +47,7 @@ struct pt_regs
 			unsigned long result;
 		};
 	};
-
+#if defined(CONFIG_PPC64) || defined(CONFIG_PPC_KUAP)
 	union {
 		struct {
 #ifdef CONFIG_PPC64
@@ -67,6 +67,7 @@ struct pt_regs
 		};
 		unsigned long __pad[4];	/* Maintain 16 byte interrupt stack alignment */
 	};
+#endif
 };
 #endif
 
-- 
2.25.0