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[83.28.43.246]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-2ff178dfb6dsm21451531fa.20.2024.11.12.09.10.20 (version=TLS1_2 cipher=AES128-SHA bits=128/128); Tue, 12 Nov 2024 09:10:20 -0800 (PST) Date: Tue, 12 Nov 2024 18:10:17 +0100 From: =?UTF-8?B?TWljaGHFgg==?= Pecio To: "Russell King (Oracle)" Cc: linux-arm-kernel@lists.infradead.org, Linus Walleij Subject: Re: cacheflush completely broken, suspecting PAN+LPAE Message-ID: <20241112181017.03992d1f@foxbook> In-Reply-To: References: <20241111233817.2f824c19@foxbook> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241112_091025_352447_27F8F485 X-CRM114-Status: GOOD ( 18.72 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, 12 Nov 2024 10:21:36 +0000, Russell King (Oracle) wrote: > From: "Russell King (Oracle)" > Subject: [PATCH] ARM: fix cacheflush with PAN >=20 > It seems that the cacheflush syscall got broken when PAN was > implemented. User access was not enabled around the cache maintenance > instructions, causing them to fault. >=20 > Fixes: a5e090acbf54 ("ARM: software-based priviledged-no-access support") For the record, non-LPAE seems to be OK, so for me it was 7af5b901e847. > Reported-by: From: Micha=C5=82 Pecio "From:" perhaps not strictly necessary ;) Tested-by: Micha=C5=82 Pecio That was it. With this patch gdb starts normally, does 295 cacheflush calls and all of them succeed, with ARM_LPAE and ARM_PAN enabled. > Signed-off-by: Russell King (Oracle) > --- > arch/arm/kernel/traps.c | 3 +++ > 1 file changed, 3 insertions(+) >=20 > diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c > index 54dcdcde3f77..6518771c1496 100644 > --- a/arch/arm/kernel/traps.c > +++ b/arch/arm/kernel/traps.c > @@ -574,6 +574,7 @@ static int bad_syscall(int n, struct pt_regs *regs) > static inline int > __do_cache_op(unsigned long start, unsigned long end) > { > + unsigned int ua_flags; > int ret; > =20 > do { > @@ -582,7 +583,9 @@ __do_cache_op(unsigned long start, unsigned long end) > if (fatal_signal_pending(current)) > return 0; > =20 > + ua_flags =3D uaccess_save_and_enable(); > ret =3D flush_icache_user_range(start, start + chunk); > + uaccess_restore(ua_flags); > if (ret) > return ret; > =20 > --=20 > 2.30.2