lwn.git/arch/arm64/kernel/signal32.c, branch docs-5.10-3

arm64: compat: Always use sigpage for sigreturn trampoline

2020-06-23T13:56:24+00:00

The 32-bit sigreturn trampoline in the compat sigpage matches the binary representation of the arch/arm/ sigpage exactly. This is important for debuggers (e.g. GDB) and unwinders (e.g. libunwind) since they rely on matching the instruction sequence in order to identify that they are unwinding through a signal. The same cannot be said for the sigreturn trampoline in the compat vDSO, which defeats the unwinder heuristics and instead attempts to use unwind directives for the unwinding. This is in contrast to arch/arm/, which never uses the vDSO for sigreturn. Ensure compatibility with arch/arm/ and existing unwinders by always using the sigpage for the sigreturn trampoline, regardless of the presence of the compat vDSO. Reviewed-by: Vincenzo Frascino Reviewed-by: Ard Biesheuvel Reviewed-by: Mark Rutland Signed-off-by: Will Deacon

arm64: compat: Allow 32-bit vdso and sigpage to co-exist

2020-06-23T13:47:03+00:00

In preparation for removing the signal trampoline from the compat vDSO, allow the sigpage and the compat vDSO to co-exist. For the moment the vDSO signal trampoline will still be used when built. Subsequent patches will move to the sigpage consistently. Acked-by: Dave Martin Reviewed-by: Vincenzo Frascino Reviewed-by: Ard Biesheuvel Reviewed-by: Mark Rutland Signed-off-by: Will Deacon

arm64: signal: nofpsimd: Handle fp/simd context for signal frames

2020-01-14T17:11:46+00:00

Make sure we try to save/restore the vfp/fpsimd context for signal handling only when the fp/simd support is available. Otherwise, skip the frames. Cc: Will Deacon Cc: Mark Rutland Reviewed-by: Ard Biesheuvel Reviewed-by: Catalin Marinas Signed-off-by: Suzuki K Poulose Signed-off-by: Will Deacon

arm64: compat: Get sigreturn trampolines from vDSO

2019-06-22T19:21:09+00:00

When the compat vDSO is enabled, the sigreturn trampolines are not anymore available through [sigpage] but through [vdso]. Add the relevant code the enable the feature. Signed-off-by: Vincenzo Frascino Signed-off-by: Thomas Gleixner Tested-by: Shijith Thotton Tested-by: Andre Przywara Cc: linux-arch@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-mips@vger.kernel.org Cc: linux-kselftest@vger.kernel.org Cc: Catalin Marinas Cc: Will Deacon Cc: Arnd Bergmann Cc: Russell King Cc: Ralf Baechle Cc: Paul Burton Cc: Daniel Lezcano Cc: Mark Salyzyn Cc: Peter Collingbourne Cc: Shuah Khan Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Rasmus Villemoes Cc: Huw Davies Link: https://lkml.kernel.org/r/20190621095252.32307-15-vincenzo.frascino@arm.com

arm64: compat: Expose signal related structures

2019-06-22T19:21:07+00:00

The compat signal data structures are required as part of the compat vDSO implementation in order to provide the unwinding information for the sigreturn trampolines. Expose these data structures as part of signal32.h. Signed-off-by: Vincenzo Frascino Signed-off-by: Thomas Gleixner Tested-by: Shijith Thotton Tested-by: Andre Przywara Cc: linux-arch@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-mips@vger.kernel.org Cc: linux-kselftest@vger.kernel.org Cc: Catalin Marinas Cc: Will Deacon Cc: Arnd Bergmann Cc: Russell King Cc: Ralf Baechle Cc: Paul Burton Cc: Daniel Lezcano Cc: Mark Salyzyn Cc: Peter Collingbourne Cc: Shuah Khan Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Rasmus Villemoes Cc: Huw Davies Link: https://lkml.kernel.org/r/20190621095252.32307-8-vincenzo.frascino@arm.com

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 234

2019-06-19T15:09:07+00:00

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not see http www gnu org licenses extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 503 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Alexios Zavras Reviewed-by: Allison Randal Reviewed-by: Enrico Weigelt Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190602204653.811534538@linutronix.de Signed-off-by: Greg Kroah-Hartman

arm64: compat: Alloc separate pages for vectors and sigpage

2019-04-23T17:01:31+00:00

For AArch32 tasks, we install a special "[vectors]" page that contains the sigreturn trampolines and kuser helpers, which is mapped at a fixed address specified by the kuser helpers ABI. Having the sigreturn trampolines in the same page as the kuser helpers makes it impossible to disable the kuser helpers independently. Follow the Arm implementation, by moving the signal trampolines out of the "[vectors]" page and into their own "[sigpage]". Cc: Catalin Marinas Cc: Will Deacon Signed-off-by: Vincenzo Frascino Reviewed-by: Catalin Marinas [will: tweaked comments and fixed sparse warning] Signed-off-by: Will Deacon

Remove 'type' argument from access_ok() function

2019-01-04T02:57:57+00:00

Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument of the user address range verification function since we got rid of the old racy i386-only code to walk page tables by hand. It existed because the original 80386 would not honor the write protect bit when in kernel mode, so you had to do COW by hand before doing any user access. But we haven't supported that in a long time, and these days the 'type' argument is a purely historical artifact. A discussion about extending 'user_access_begin()' to do the range checking resulted this patch, because there is no way we're going to move the old VERIFY_xyz interface to that model. And it's best done at the end of the merge window when I've done most of my merges, so let's just get this done once and for all. This patch was mostly done with a sed-script, with manual fix-ups for the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form. There were a couple of notable cases: - csky still had the old "verify_area()" name as an alias. - the iter_iov code had magical hardcoded knowledge of the actual values of VERIFY_{READ,WRITE} (not that they mattered, since nothing really used it) - microblaze used the type argument for a debug printout but other than those oddities this should be a total no-op patch. I tried to fix up all architectures, did fairly extensive grepping for access_ok() uses, and the changes are trivial, but I may have missed something. Any missed conversion should be trivially fixable, though. Signed-off-by: Linus Torvalds

arm64: use {COMPAT,}SYSCALL_DEFINE0 for sigreturn

2018-07-12T13:49:48+00:00

We don't currently annotate our various sigreturn functions as syscalls, as we need to do to use pt_regs syscall wrappers. Let's mark them as real syscalls. For compat_sys_sigreturn and compat_sys_rt_sigreturn, this changes the return type from int to long, matching the prototypes in sys32.c. Signed-off-by: Mark Rutland Reviewed-by: Dominik Brodowski Acked-by: Catalin Marinas Cc: Will Deacon Signed-off-by: Will Deacon

arm64: remove sigreturn wrappers

2018-07-12T13:40:39+00:00

The arm64 sigreturn* syscall handlers are non-standard. Rather than taking a number of user parameters in registers as per the AAPCS, they expect the pt_regs as their sole argument. To make this work, we override the syscall definitions to invoke wrappers written in assembly, which mov the SP into x0, and branch to their respective C functions. On other architectures (such as x86), the sigreturn* functions take no argument and instead use current_pt_regs() to acquire the user registers. This requires less boilerplate code, and allows for other features such as interposing C code in this path. This patch takes the same approach for arm64. Signed-off-by: Mark Rutland Tentatively-reviewed-by: Dave Martin Reviewed-by: Catalin Marinas Cc: Will Deacon Signed-off-by: Will Deacon