From 43d4da2c45b2f5d62f8a79ff7c6f95089bb24656 Mon Sep 17 00:00:00 2001 From: Dave Martin Date: Tue, 31 Oct 2017 15:51:13 +0000 Subject: arm64/sve: ptrace and ELF coredump support MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This patch defines and implements a new regset NT_ARM_SVE, which describes a thread's SVE register state. This allows a debugger to manipulate the SVE state, as well as being included in ELF coredumps for post-mortem debugging. Because the regset size and layout are dependent on the thread's current vector length, it is not possible to define a C struct to describe the regset contents as is done for existing regsets. Instead, and for the same reasons, NT_ARM_SVE is based on the freeform variable-layout approach used for the SVE signal frame. Additionally, to reduce debug overhead when debugging threads that might or might not have live SVE register state, NT_ARM_SVE may be presented in one of two different formats: the old struct user_fpsimd_state format is embedded for describing the state of a thread with no live SVE state, whereas a new variable-layout structure is embedded for describing live SVE state. This avoids a debugger needing to poll NT_PRFPREG in addition to NT_ARM_SVE, and allows existing userspace code to handle the non-SVE case without too much modification. For this to work, NT_ARM_SVE is defined with a fixed-format header of type struct user_sve_header, which the recipient can use to figure out the content, size and layout of the reset of the regset. Accessor macros are defined to allow the vector-length-dependent parts of the regset to be manipulated. Signed-off-by: Alan Hayward Signed-off-by: Dave Martin Reviewed-by: Catalin Marinas Cc: Alex Bennée Cc: Okamoto Takayuki Signed-off-by: Will Deacon --- arch/arm64/kernel/fpsimd.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) (limited to 'arch/arm64/kernel/fpsimd.c') diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index 1e531156f1d7..b82d44693b9d 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -428,6 +428,66 @@ void sve_alloc(struct task_struct *task) BUG_ON(!task->thread.sve_state); } + +/* + * Ensure that task->thread.sve_state is up to date with respect to + * the user task, irrespective of when SVE is in use or not. + * + * This should only be called by ptrace. task must be non-runnable. + * task->thread.sve_state must point to at least sve_state_size(task) + * bytes of allocated kernel memory. + */ +void fpsimd_sync_to_sve(struct task_struct *task) +{ + if (!test_tsk_thread_flag(task, TIF_SVE)) + fpsimd_to_sve(task); +} + +/* + * Ensure that task->thread.fpsimd_state is up to date with respect to + * the user task, irrespective of whether SVE is in use or not. + * + * This should only be called by ptrace. task must be non-runnable. + * task->thread.sve_state must point to at least sve_state_size(task) + * bytes of allocated kernel memory. + */ +void sve_sync_to_fpsimd(struct task_struct *task) +{ + if (test_tsk_thread_flag(task, TIF_SVE)) + sve_to_fpsimd(task); +} + +/* + * Ensure that task->thread.sve_state is up to date with respect to + * the task->thread.fpsimd_state. + * + * This should only be called by ptrace to merge new FPSIMD register + * values into a task for which SVE is currently active. + * task must be non-runnable. + * task->thread.sve_state must point to at least sve_state_size(task) + * bytes of allocated kernel memory. + * task->thread.fpsimd_state must already have been initialised with + * the new FPSIMD register values to be merged in. + */ +void sve_sync_from_fpsimd_zeropad(struct task_struct *task) +{ + unsigned int vq; + void *sst = task->thread.sve_state; + struct fpsimd_state const *fst = &task->thread.fpsimd_state; + unsigned int i; + + if (!test_tsk_thread_flag(task, TIF_SVE)) + return; + + vq = sve_vq_from_vl(task->thread.sve_vl); + + memset(sst, 0, SVE_SIG_REGS_SIZE(vq)); + + for (i = 0; i < 32; ++i) + memcpy(ZREG(sst, vq, i), &fst->vregs[i], + sizeof(fst->vregs[i])); +} + int sve_set_vector_length(struct task_struct *task, unsigned long vl, unsigned long flags) { -- cgit v1.2.3