kernel.git/arch/arm64/kernel/ptrace.c, branch linux-4.14.y

arm64: ptrace: Override SPSR.SS when single-stepping is enabled

2020-07-22T07:22:28Z

commit 3a5a4366cecc25daa300b9a9174f7fdd352b9068 upstream. Luis reports that, when reverse debugging with GDB, single-step does not function as expected on arm64: | I've noticed, under very specific conditions, that a PTRACE_SINGLESTEP | request by GDB won't execute the underlying instruction. As a consequence, | the PC doesn't move, but we return a SIGTRAP just like we would for a | regular successful PTRACE_SINGLESTEP request. The underlying problem is that when the CPU register state is restored as part of a reverse step, the SPSR.SS bit is cleared and so the hardware single-step state can transition to the "active-pending" state, causing an unexpected step exception to be taken immediately if a step operation is attempted. In hindsight, we probably shouldn't have exposed SPSR.SS in the pstate accessible by the GPR regset, but it's a bit late for that now. Instead, simply prevent userspace from configuring the bit to a value which is inconsistent with the TIF_SINGLESTEP state for the task being traced. Cc: Cc: Mark Rutland Cc: Keno Fischer Link: https://lore.kernel.org/r/1eed6d69-d53d-9657-1fc9-c089be07f98c@linaro.org Reported-by: Luis Machado Tested-by: Luis Machado Signed-off-by: Will Deacon Signed-off-by: Greg Kroah-Hartman

arm64: ptrace: map SPSR_ELx<->PSR for compat tasks

2020-04-02T14:34:28Z

commit 76fc52bd07d3e9cb708f1a50b60c825c96acd606 upstream. The SPSR_ELx format for exceptions taken from AArch32 is slightly different to the AArch32 PSR format. Map between the two in the compat ptrace code. Signed-off-by: Mark Rutland Fixes: 7206dc93a58fb764 ("arm64: Expose Arm v8.4 features") Cc: Catalin Marinas Cc: Suzuki Poulose Cc: Will Deacon Signed-off-by: Will Deacon Cc: Guenter Roeck Signed-off-by: Greg Kroah-Hartman

arm64: ptrace: nofpsimd: Fail FP/SIMD regset operations

2020-02-28T15:35:52Z

commit c9d66999f064947e6b577ceacc1eb2fbca6a8d3c upstream When fp/simd is not supported on the system, fail the operations of FP/SIMD regsets. Cc: stable@vger.kernel.org # v4.14 Cc: Will Deacon Cc: Mark Rutland Reviewed-by: Ard Biesheuvel Reviewed-by: Catalin Marinas Signed-off-by: Suzuki K Poulose Signed-off-by: Sasha Levin

arm64: fix SSBS sanitization

2019-10-29T08:17:24Z

[ Upstream commit f54dada8274643e3ff4436df0ea124aeedc43cae ] In valid_user_regs() we treat SSBS as a RES0 bit, and consequently it is unexpectedly cleared when we restore a sigframe or fiddle with GPRs via ptrace. This patch fixes valid_user_regs() to account for this, updating the function to refer to the latest ARM ARM (ARM DDI 0487D.a). For AArch32 tasks, SSBS appears in bit 23 of SPSR_EL1, matching its position in the AArch32-native PSR format, and we don't need to translate it as we have to for DIT. There are no other bit assignments that we need to account for today. As the recent documentation describes the DIT bit, we can drop our comment regarding DIT. While removing SSBS from the RES0 masks, existing inconsistent whitespace is corrected. Fixes: d71be2b6c0e19180 ("arm64: cpufeature: Detect SSBS and advertise to userspace") Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: Suzuki K Poulose Cc: Will Deacon Signed-off-by: Will Deacon Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman

arm64: don't zero DIT on signal return

2019-10-29T08:17:23Z

[ Upstream commit 1265132127b63502d34e0f58c8bdef3a4dc927c2 ] Currently valid_user_regs() treats SPSR_ELx.DIT as a RES0 bit, causing it to be zeroed upon exception return, rather than preserved. Thus, code relying on DIT will not function as expected, and may expose an unexpected timing sidechannel. Let's remove DIT from the set of RES0 bits, such that it is preserved. At the same time, the related comment is updated to better describe the situation, and to take into account the most recent documentation of SPSR_ELx, in ARM DDI 0487C.a. Signed-off-by: Mark Rutland Fixes: 7206dc93a58fb764 ("arm64: Expose Arm v8.4 features") Cc: Catalin Marinas Cc: Suzuki K Poulose Cc: Will Deacon Signed-off-by: Will Deacon Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman

arm64: fix possible spectre-v1 write in ptrace_hbp_set_event()

2018-09-26T06:38:03Z

[ Upstream commit 14d6e289a89780377f8bb09de8926d3c62d763cd ] It's possible for userspace to control idx. Sanitize idx when using it as an array index, to inhibit the potential spectre-v1 write gadget. Found by smatch. Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: Will Deacon Signed-off-by: Will Deacon Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

arm64: fix possible spectre-v1 in ptrace_hbp_get_event()

2018-06-20T19:02:49Z

[ Upstream commit 19791a7ca674fb3009bb068260e852a2f05b605c ] It's possible for userspace to control idx. Sanitize idx when using it as an array index. Found by smatch. Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: Will Deacon Signed-off-by: Will Deacon Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

arm64: ptrace: remove addr_limit manipulation

2018-06-20T19:02:48Z

[ Upstream commit 59275a0c037ed6fabd6354730f1e3104264ab719 ] We transiently switch to KERNEL_DS in compat_ptrace_gethbpregs() and compat_ptrace_sethbpregs(), but in either case this is pointless as we don't perform any uaccess during this window. let's rip out the redundant addr_limit manipulation. Acked-by: Catalin Marinas Signed-off-by: Mark Rutland Cc: Will Deacon Signed-off-by: Will Deacon Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

Merge branch 'arm64/vmap-stack' of git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux into for-next/core

2017-08-15T17:40:58Z

* 'arm64/vmap-stack' of git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux: arm64: add VMAP_STACK overflow detection arm64: add on_accessible_stack() arm64: add basic VMAP_STACK support arm64: use an irq stack pointer arm64: assembler: allow adr_this_cpu to use the stack pointer arm64: factor out entry stack manipulation efi/arm64: add EFI_KIMG_ALIGN arm64: move SEGMENT_ALIGN to arm64: clean up irq stack definitions arm64: clean up THREAD_* definitions arm64: factor out PAGE_* and CONT_* definitions arm64: kernel: remove {THREAD,IRQ_STACK}_START_SP fork: allow arch-override of VMAP stack alignment arm64: remove __die()'s stack dump

arm64: clean up irq stack definitions

2017-08-15T17:35:14Z

Before we add yet another stack to the kernel, it would be nice to ensure that we consistently organise stack definitions and related helper functions. This patch moves the basic IRQ stack defintions to to live with their task stack counterparts. Helpers used for unwinding are moved into , where subsequent patches will add helpers for other stacks. Includes are fixed up accordingly. This patch is a pure refactoring -- there should be no functional changes as a result of this patch. Signed-off-by: Mark Rutland Reviewed-by: Will Deacon Tested-by: Laura Abbott Cc: Ard Biesheuvel Cc: Catalin Marinas Cc: James Morse