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b=IyKNWJWIlnnugQvpgVATmIqiPrEA8tV6QJpPNzAgUx9dbs16fukw9ah/I76irlgIk GL9fc6/3CCT8oYMK4xnI0wIStYHutNCxAWQKMMjdJc5MbWXD1tzq82iUuEUkbnxvI2 e2ttWlClhCs/aSJv++M7TToS5QknmRybvEJULMu8+9NyY2TZ57iSUa0bNLkwrE4Lby 8bCOl1oOwtyoPcIbar4kYjXu3wlAZSUg2R3LLoiujFwdvRACaMvWbUQAQATXYZvjqd CEu+pwLJUL/h7Vq2xhJTS28dYPmFgJ/f+TvllsR+/lUOichs51BzWyyrEqpLwI9RdV HeyKNUtvr7Aog== From: Sasha Levin To: stable@vger.kernel.org, chenhuacai@kernel.org Cc: Xiaotian Wu , Miao Wang , Xing Li , Hongchen Zhang , Rui Wang , Huacai Chen , linux-mm@kvack.org, loongarch@lists.linux.dev, linux-kernel@vger.kernel.org Subject: FAILED: Patch "LoongArch: Change __my_cpu_offset definition to avoid mis-optimization" failed to apply to 5.4-stable tree Date: Wed, 27 Mar 2024 08:22:10 -0400 Message-ID: <20240327122210.2837487-1-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 MIME-Version: 1.0 X-Patchwork-Hint: ignore X-stable: review Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 472A140011 X-Stat-Signature: tsnatm47qwk1ye4kqbdky431djhc5boa X-HE-Tag: 1711542135-857320 X-HE-Meta: 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 6eusiHHV MOwnYJtBx6pILjPAYirG7L0HFYUUytfN3NjhU0ntYUBz/O+mGmhCz+hJo3+aInCZU3owN82klzapbDF+gL8Jnyg4iPNVU8Kj6fdNg3gkFh3ICROARKSteZGpl6zUDBMp53gPIT8HAka26X3AGqXvPhTRG3//a7uolS6igc5qQbdxFBYLa4IlUAdfnfccWOTAHCee/qVELZ7PzF9oI3C3gab70DqicKj1ZhYYy3397UXOH2qXkRqocWZl7jQycNJuRIK6+SvpOlHvHx2zP89C5VWm/8LN9Ei/9n+F43iKxrr+S55R+qA8WWgEh4+O59zHb8Qig09t4946MsRQI+PLrscrAMg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From c87e12e0e8c1241410e758e181ca6bf23efa5b5b Mon Sep 17 00:00:00 2001 From: Huacai Chen Date: Tue, 19 Mar 2024 15:50:34 +0800 Subject: [PATCH] LoongArch: Change __my_cpu_offset definition to avoid mis-optimization >From GCC commit 3f13154553f8546a ("df-scan: remove ad-hoc handling of global regs in asms"), global registers will no longer be forced to add to the def-use chain. Then current_thread_info(), current_stack_pointer and __my_cpu_offset may be lifted out of the loop because they are no longer treated as "volatile variables". This optimization is still correct for the current_thread_info() and current_stack_pointer usages because they are associated to a thread. However it is wrong for __my_cpu_offset because it is associated to a CPU rather than a thread: if the thread migrates to a different CPU in the loop, __my_cpu_offset should be changed. Change __my_cpu_offset definition to treat it as a "volatile variable", in order to avoid such a mis-optimization. Cc: stable@vger.kernel.org Reported-by: Xiaotian Wu Reported-by: Miao Wang Signed-off-by: Xing Li Signed-off-by: Hongchen Zhang Signed-off-by: Rui Wang Signed-off-by: Huacai Chen --- arch/loongarch/include/asm/percpu.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/loongarch/include/asm/percpu.h b/arch/loongarch/include/asm/percpu.h index 9b36ac003f890..8f290e5546cf7 100644 --- a/arch/loongarch/include/asm/percpu.h +++ b/arch/loongarch/include/asm/percpu.h @@ -29,7 +29,12 @@ static inline void set_my_cpu_offset(unsigned long off) __my_cpu_offset = off; csr_write64(off, PERCPU_BASE_KS); } -#define __my_cpu_offset __my_cpu_offset + +#define __my_cpu_offset \ +({ \ + __asm__ __volatile__("":"+r"(__my_cpu_offset)); \ + __my_cpu_offset; \ +}) #define PERCPU_OP(op, asm_op, c_op) \ static __always_inline unsigned long __percpu_##op(void *ptr, \ -- 2.43.0