From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Wed, 30 Jul 2014 12:30:13 +0100 Subject: [PATCH v2 1/3] arm64: spin-table: handle unmapped cpu-release-addrs In-Reply-To: <1406717944-24725-2-git-send-email-ard.biesheuvel@linaro.org> References: <1406717944-24725-1-git-send-email-ard.biesheuvel@linaro.org> <1406717944-24725-2-git-send-email-ard.biesheuvel@linaro.org> Message-ID: <20140730113013.GL12239@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Jul 30, 2014 at 11:59:02AM +0100, Ard Biesheuvel wrote: > From: Mark Rutland > > In certain cases the cpu-release-addr of a CPU may not fall in the > linear mapping (e.g. when the kernel is loaded above this address due to > the presence of other images in memory). This is problematic for the > spin-table code as it assumes that it can trivially convert a > cpu-release-addr to a valid VA in the linear map. > > This patch modifies the spin-table code to use a temporary cached > mapping to write to a given cpu-release-addr, enabling us to support > addresses regardless of whether they are covered by the linear mapping. > > Signed-off-by: Mark Rutland > Tested-by: Mark Salter > [ardb: added (__force void *) cast] > Signed-off-by: Ard Biesheuvel > --- > arch/arm64/kernel/smp_spin_table.c | 22 +++++++++++++++++----- > 1 file changed, 17 insertions(+), 5 deletions(-) I'm nervous about this. What if the spin table sits in the same physical 64k frame as a read-sensitive device and we're running with 64k pages? Will