linux-kernel - [PATCH] x86/percpu: Fix __per_cpu_hot

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Message-ID: <20250304173455.89361-1-ubizjak@gmail.com>
Date: Tue,  4 Mar 2025 18:34:36 +0100
From: Uros Bizjak <ubizjak@...il.com>
To: x86@...nel.org,
	linux-kernel@...r.kernel.org
Cc: Uros Bizjak <ubizjak@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	Brian Gerst <brgerst@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Borislav Petkov <bp@...en8.de>,
	Ard Biesheuvel <ardb@...nel.org>,
	Linus Torvalds <torvalds@...uxfoundation.org>,
	Andy Lutomirski <luto@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH] x86/percpu: Fix __per_cpu_hot_end marker

Make __per_cpu_hot_end marker point to the end of the percpu cache
hot data, not to the end of the percpu cache hot section.

This fixes CONFIG_MPENTIUM4 case where X86_L1_CACHE_SHIFT
is set to 7 (128 bytes).

Also update assert message accordingly.

Reported-by: Ingo Molnar <mingo@...nel.org>
Closes: https://lore.kernel.org/lkml/Z8a-NVJs-pm5W-mG@gmail.com/
Cc: Brian Gerst <brgerst@...il.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Ard Biesheuvel <ardb@...nel.org>
Cc: Linus Torvalds <torvalds@...uxfoundation.org>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Uros Bizjak <ubizjak@...il.com>
---
 arch/x86/kernel/vmlinux.lds.S     | 2 +-
 include/asm-generic/vmlinux.lds.h | 3 +--
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 31f9102b107f..ccdc45e5b759 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -331,7 +331,7 @@ SECTIONS
 	}
 
 	PERCPU_SECTION(L1_CACHE_BYTES)
-	ASSERT(__per_cpu_hot_end - __per_cpu_hot_start <= 64, "percpu cache hot section too large")
+	ASSERT(__per_cpu_hot_end - __per_cpu_hot_start <= 64, "percpu cache hot data too large")
 
 	RUNTIME_CONST_VARIABLES
 	RUNTIME_CONST(ptr, USER_PTR_MAX)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 4ed0e6a013d0..58a635a6d5bd 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -1071,9 +1071,8 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG)
 	. = ALIGN(cacheline);						\
 	__per_cpu_hot_start = .;					\
 	*(SORT_BY_ALIGNMENT(.data..percpu..hot.*))			\
-	__per_cpu_hot_pad = .;						\
-	. = ALIGN(cacheline);						\
 	__per_cpu_hot_end = .;						\
+	. = ALIGN(cacheline);						\
 	*(.data..percpu..read_mostly)					\
 	. = ALIGN(cacheline);						\
 	*(.data..percpu)						\
-- 
2.42.0