From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave.Martin@arm.com (Dave Martin) Date: Fri, 9 Sep 2016 15:15:41 +0100 Subject: [RFC PATCH 0/5] arm64: Signal context expansion Message-ID: <1473430576-20792-1-git-send-email-Dave.Martin@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org In preparation for supporting the ARM Scalable Vector Extension in the Linux kernel, it is necessary to be able to save more data in the signal frame than can be accommodated in the existing arm64 signal frame structure. To minimise ABI impact the current structures are retained as-is, and a new extra_context record is defined, which (if present) declares some additional space beyond the standard arm64 signal frame. This new record can be added in sigframe.__reserved[] if there is a need to allocate extra space beyond the standard signal frame. The extra block of memory referenced by extra_context can then be parsed in the same way as sigcontext.__reserved[]. Old code should just ignore the whole thing as an unrecognised record. To maintain backward compatibility, signal context records defined today are always placed directly in __reserved[], never in the block referenced by extra_context. This series also does some refactoring in order to make it easier to add records to the signal frame in the future, using the new expansion mechanism. The extra_context mechanism is hidden behind a simple allocator that grows and signal frame only as needed. Note: this series makes rt_sigreturn somewhat stricter about parsing the signal frame than previously: violators will be SEGV'd. This should only be an ABI break for software that was doing something wrong in the first place, but I'm open to suggestions if people have concerns about it. Dave Martin (5): arm64: signal: Refactor sigcontext parsing in rt_sigreturn arm64: signal: factor frame layout and population into separate passes arm64: signal: factor out signal frame record allocation arm64: signal: Allocate extra sigcontext space as needed arm64: signal: Parse extra_context during sigreturn arch/arm64/include/uapi/asm/sigcontext.h | 27 +++ arch/arm64/kernel/signal.c | 355 ++++++++++++++++++++++++++++--- 2 files changed, 350 insertions(+), 32 deletions(-) -- 2.1.4