From mboxrd@z Thu Jan 1 00:00:00 1970 From: julien.thierry@arm.com (Julien Thierry) Date: Fri, 19 Oct 2018 09:07:36 +0100 Subject: [PATCH 0/7] Ensure stack is aligned for kernel entries In-Reply-To: <1537970184-44348-1-git-send-email-julien.thierry@arm.com> References: <1537970184-44348-1-git-send-email-julien.thierry@arm.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Gentle ping on this series. On 26/09/18 14:56, Julien Thierry wrote: > Hi, > > Having SCTLR_ELx.SA enabled requires the SP to be 16-bytes aligned before > using it to access memory. When taking an exception, it is possible that > the context during which the exception occured had SP mis-aligned. The > entry code needs to make sure that the stack is aligned before using it to > save the context. > > This is only a concern when taking exception from an EL using the same > SP_ELx as the handler. In other cases it can be assumed that the SP being > picked up on exception entry is aligned under the condition that SP is > always aligned when doing eret to an EL using a different SP. > > On Juno I see a runtime difference <1% for hackbench. If I do not include > the fast path at EL1 (patch 4) I see a diff of 1-2%. > > For EL2 entries, a bit of clean up of stuff getting patched in the vector > has been needed. > > Cheers, > > Julien > > --> > > Julien Thierry (7): > arm64: Add static check for pt_regs alignment > arm64: sdei: Always use sdei stack for sdei events > arm64: Align stack when taking exception from EL1 > arm64: Add fast-path for stack alignment > arm64: Do not apply BP hardening for hyp entries from EL2 > arm64: Do not apply vector harderning for hyp entries from EL2 > arm64: kvm: Align stack for exception coming from EL2 > > arch/arm64/include/asm/assembler.h | 9 +++++ > arch/arm64/include/asm/ptrace.h | 2 + > arch/arm64/include/asm/sdei.h | 2 - > arch/arm64/kernel/cpu_errata.c | 10 ++++- > arch/arm64/kernel/entry.S | 43 +++++++++++++++++++-- > arch/arm64/kernel/sdei.c | 23 ++++------- > arch/arm64/kvm/hyp/hyp-entry.S | 78 +++++++++++++++++++++++++++++++------- > drivers/firmware/Kconfig | 1 + > 8 files changed, 132 insertions(+), 36 deletions(-) > > -- > 1.9.1 > -- Julien Thierry