[RFC PATCH 08/10] arm64/sve: ptrace: Wire up vector length control and reporting
From: Dave.Martin@arm.com (Dave Martin)
Date: 2017-01-12 11:26:07
Also in:
linux-arch
Subsystem:
arm64 port (aarch64 architecture), ptrace support, the rest · Maintainers:
Catalin Marinas, Will Deacon, Oleg Nesterov, Linus Torvalds
This patch adds support for manipulating a task's vector length at runtime via ptrace. As a simplification, we turn the task back into an FPSIMD-only task when changing the vector length. If the register data is written too, we then turn the task back into an SVE task, with changed task_struct layout for the SVE data, before the actual data writing is done. Because the vector length is now variable, sve_get() now needs to return the real maximum for user_sve_header.max_vl, since .vl may be less than this (that's the whole point). Signed-off-by: Dave Martin <Dave.Martin@arm.com> --- arch/arm64/include/asm/fpsimd.h | 1 + arch/arm64/include/uapi/asm/ptrace.h | 5 +++++ arch/arm64/kernel/ptrace.c | 25 +++++++++++++++---------- 3 files changed, 21 insertions(+), 10 deletions(-)
diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h
index 1ec2363..0f1b068 100644
--- a/arch/arm64/include/asm/fpsimd.h
+++ b/arch/arm64/include/asm/fpsimd.h@@ -105,6 +105,7 @@ extern void sve_load_state(void const *state, u32 const *pfpsr, extern unsigned int sve_get_vl(void); extern int sve_set_vector_length(struct task_struct *task, unsigned long vl, unsigned long flags); +extern int sve_max_vl; /* * FPSIMD/SVE synchronisation helpers for ptrace:
diff --git a/arch/arm64/include/uapi/asm/ptrace.h b/arch/arm64/include/uapi/asm/ptrace.h
index 48b57a0..bcb542d 100644
--- a/arch/arm64/include/uapi/asm/ptrace.h
+++ b/arch/arm64/include/uapi/asm/ptrace.h@@ -64,6 +64,8 @@ #ifndef __ASSEMBLY__ +#include <linux/prctl.h> + /* * User structures for general purpose, floating point and debug registers. */
@@ -108,6 +110,9 @@ struct user_sve_header { #define SVE_PT_REGS_FPSIMD 0 #define SVE_PT_REGS_SVE SVE_PT_REGS_MASK +#define SVE_PT_VL_THREAD PR_SVE_SET_VL_THREAD +#define SVE_PT_VL_INHERIT PR_SVE_SET_VL_INHERIT + /* * The remainder of the SVE state follows struct user_sve_header. The
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 32debb8..7e40039 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c@@ -741,14 +741,15 @@ static int sve_get(struct task_struct *target, BUG_ON(!sve_vl_valid(header.vl)); vq = sve_vq_from_vl(header.vl); - /* Until runtime or per-task vector length changing is supported: */ - header.max_vl = header.vl; + BUG_ON(!sve_vl_valid(sve_max_vl)); + header.max_vl = sve_max_vl; header.flags = test_tsk_thread_flag(target, TIF_SVE) ? SVE_PT_REGS_SVE : SVE_PT_REGS_FPSIMD; header.size = SVE_PT_SIZE(vq, header.flags); - header.max_size = SVE_PT_SIZE(vq, SVE_PT_REGS_SVE); + header.max_size = SVE_PT_SIZE(sve_vq_from_vl(header.max_vl), + SVE_PT_REGS_SVE); ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &header, 0, sizeof(header));
@@ -830,14 +831,18 @@ static int sve_set(struct task_struct *target, if (ret) goto out; - if (header.vl != target->thread.sve_vl) - return -EINVAL; - - BUG_ON(!sve_vl_valid(header.vl)); - vq = sve_vq_from_vl(header.vl); + /* + * Apart from PT_SVE_REGS_MASK, all PT_SVE_* flags are consumed by + * sve_set_vector_length(), which will also validate them for us: + */ + ret = sve_set_vector_length(target, header.vl, + header.flags & ~SVE_PT_REGS_MASK); + if (ret) + goto out; - if (header.flags & ~SVE_PT_REGS_MASK) - return -EINVAL; + /* Actual VL set may be less than the user asked for: */ + BUG_ON(!sve_vl_valid(target->thread.sve_vl)); + vq = sve_vq_from_vl(target->thread.sve_vl); /* Registers: FPSIMD-only case */
--
2.1.4