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From: Michael Neuling <mikey@neuling.org>
To: "Björn Töpel" <bjorn@rivosinc.com>,
	"Mike Rapoport (Microsoft)" <rppt@kernel.org>,
	"Vishal Moola (Oracle)" <vishal.moola@gmail.com>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Aleksa Paunovic" <aleksa.paunovic@htecgroup.com>,
	"Aleksandar Rikalo" <arikalo@gmail.com>,
	"Alexandre Ghiti" <alex@ghiti.fr>,
	"Andrew Jones" <ajones@ventanamicro.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"David Hildenbrand" <david@redhat.com>,
	"Djordje Todorovic" <djordje.todorovic@htecgroup.com>,
	"Guo Ren" <guoren@kernel.org>,
	"Junhui Liu" <junhui.liu@pigmoral.tech>,
	"Kevin Brodsky" <kevin.brodsky@arm.com>,
	"Lorenzo Stoakes" <ljs@kernel.org>,
	"Nam Cao" <namcao@linutronix.de>,
	"Oleg Nesterov" <oleg@redhat.com>,
	"Oscar Salvador" <osalvador@suse.de>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Paul Walmsley" <pjw@kernel.org>,
	"Qinglin Pan" <panqinglin2020@iscas.ac.cn>,
	"Raj Vishwanathan4" <rvishwanathan@mips.com>,
	linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org
Cc: Michael Neuling <mikey@neuling.org>
Subject: [PATCH 1/5] riscv: errata: Fix bitwise vs logical AND in MIPS errata patching
Date: Thu,  9 Apr 2026 09:11:39 +0000	[thread overview]
Message-ID: <20260409091143.1348853-2-mikey@neuling.org> (raw)
In-Reply-To: <20260409091143.1348853-1-mikey@neuling.org>

The condition checking whether a specific errata needs patching uses
logical AND (&&) instead of bitwise AND (&). Since logical AND only
checks that both operands are non-zero, this causes all errata patches
to be applied whenever any single errata is detected, rather than only
applying the matching one.

The SiFive errata implementation correctly uses bitwise AND for the same
check.

Fixes: 0b0ca959d2 ("riscv: errata: Fix the PAUSE Opcode for MIPS P8700")
Signed-off-by: Michael Neuling <mikey@neuling.org>
Assisted-by: Cursor:claude-4.6-opus-high-thinking
---
 arch/riscv/errata/mips/errata.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/errata/mips/errata.c b/arch/riscv/errata/mips/errata.c
index e984a81522..2c3dc2259e 100644
--- a/arch/riscv/errata/mips/errata.c
+++ b/arch/riscv/errata/mips/errata.c
@@ -57,7 +57,7 @@ void mips_errata_patch_func(struct alt_entry *begin, struct alt_entry *end,
 		}
 
 		tmp = (1U << alt->patch_id);
-		if (cpu_req_errata && tmp) {
+		if (cpu_req_errata & tmp) {
 			mutex_lock(&text_mutex);
 			patch_text_nosync(ALT_OLD_PTR(alt), ALT_ALT_PTR(alt),
 					  alt->alt_len);
-- 
2.43.0


  reply	other threads:[~2026-04-09  9:12 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-04-09  9:11 [PATCH 0/5] riscv: Assorted bug fixes Michael Neuling
2026-04-09  9:11 ` Michael Neuling [this message]
2026-04-09  9:11 ` [PATCH 2/5] riscv: ptrace: Fix register corruption in compat_riscv_gpr_set on error Michael Neuling
2026-04-09  9:11 ` [PATCH 3/5] riscv: mm: Fix NULL pointer dereference in __set_memory Michael Neuling
2026-04-09 12:37   ` David Hildenbrand (Arm)
2026-04-10  6:23     ` Michael Neuling
2026-04-10  7:42       ` David Hildenbrand (Arm)
2026-04-10  7:53         ` Mike Rapoport
2026-04-10  7:59           ` David Hildenbrand (Arm)
2026-04-10  8:55             ` Michael Neuling
2026-04-09  9:11 ` [PATCH 4/5] riscv: mm: Fix NULL dereferences in napot hugetlb functions Michael Neuling
2026-04-09 12:36   ` David Hildenbrand (Arm)
2026-04-09  9:11 ` [PATCH 5/5] riscv: mm: Fix TOCTOU race in remove_pte_mapping Michael Neuling
2026-04-09 12:32   ` David Hildenbrand (Arm)

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