From b7538d55a36bcf18f58c6ed974dcc2b93a513bec Mon Sep 17 00:00:00 2001 From: Mark Brown Date: Wed, 17 Aug 2022 19:23:23 +0100 Subject: [PATCH] UPSTREAM: arm64/sme: Don't flush SVE register state when allocating SME storage Currently when taking a SME access trap we allocate storage for the SVE register state in order to be able to handle storage of streaming mode SVE. Due to the original usage in a purely SVE context the SVE register state allocation this also flushes the register state for SVE if storage was already allocated but in the SME context this is not desirable. For a SME access trap to be taken the task must not be in streaming mode so either there already is SVE register state present for regular SVE mode which would be corrupted or the task does not have TIF_SVE and the flush is redundant. Fix this by adding a flag to sve_alloc() indicating if we are in a SVE context and need to flush the state. Freshly allocated storage is always zeroed either way. Bug: 254441685 Fixes: 8bd7f91c03d8 ("arm64/sme: Implement traps and syscall handling for SME") Signed-off-by: Mark Brown Reviewed-by: Catalin Marinas Link: https://lore.kernel.org/r/20220817182324.638214-4-broonie@kernel.org Signed-off-by: Will Deacon (cherry picked from commit 826a4fdd2ada9e5923c58bdd168f31a42e958ffc) Signed-off-by: Lee Jones Change-Id: I8efef6c97c9e1743fd5f02bdda68be1afb1c8dee --- arch/arm64/include/asm/fpsimd.h | 4 ++-- arch/arm64/kernel/fpsimd.c | 10 ++++++---- arch/arm64/kernel/ptrace.c | 6 +++--- arch/arm64/kernel/signal.c | 2 +- 4 files changed, 12 insertions(+), 10 deletions(-) diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h index e00505534c2d..1926ca23aa4b 100644 --- a/arch/arm64/include/asm/fpsimd.h +++ b/arch/arm64/include/asm/fpsimd.h @@ -141,7 +141,7 @@ struct vl_info { #ifdef CONFIG_ARM64_SVE -extern void sve_alloc(struct task_struct *task); +extern void sve_alloc(struct task_struct *task, bool flush); extern void fpsimd_release_task(struct task_struct *task); extern void fpsimd_sync_to_sve(struct task_struct *task); extern void fpsimd_force_sync_to_sve(struct task_struct *task); @@ -244,7 +244,7 @@ size_t sve_state_size(struct task_struct const *task); #else /* ! CONFIG_ARM64_SVE */ -static inline void sve_alloc(struct task_struct *task) { } +static inline void sve_alloc(struct task_struct *task, bool flush) { } static inline void fpsimd_release_task(struct task_struct *task) { } static inline void sve_sync_to_fpsimd(struct task_struct *task) { } static inline void sve_sync_from_fpsimd_zeropad(struct task_struct *task) { } diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index 968c545d397e..4960d63f32ac 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -705,10 +705,12 @@ size_t sve_state_size(struct task_struct const *task) * do_sve_acc() case, there is no ABI requirement to hide stale data * written previously be task. */ -void sve_alloc(struct task_struct *task) +void sve_alloc(struct task_struct *task, bool flush) { if (task->thread.sve_state) { - memset(task->thread.sve_state, 0, sve_state_size(task)); + if (flush) + memset(task->thread.sve_state, 0, + sve_state_size(task)); return; } @@ -1378,7 +1380,7 @@ void do_sve_acc(unsigned int esr, struct pt_regs *regs) return; } - sve_alloc(current); + sve_alloc(current, true); if (!current->thread.sve_state) { force_sig(SIGKILL); return; @@ -1429,7 +1431,7 @@ void do_sme_acc(unsigned int esr, struct pt_regs *regs) return; } - sve_alloc(current); + sve_alloc(current, false); sme_alloc(current); if (!current->thread.sve_state || !current->thread.za_state) { force_sig(SIGKILL); diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index a32ff920b677..d29229d6139c 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -883,7 +883,7 @@ static int sve_set_common(struct task_struct *target, * state and ensure there's storage. */ if (target->thread.svcr != old_svcr) - sve_alloc(target); + sve_alloc(target, true); } /* Registers: FPSIMD-only case */ @@ -913,7 +913,7 @@ static int sve_set_common(struct task_struct *target, goto out; } - sve_alloc(target); + sve_alloc(target, true); if (!target->thread.sve_state) { ret = -ENOMEM; clear_tsk_thread_flag(target, TIF_SVE); @@ -1083,7 +1083,7 @@ static int za_set(struct task_struct *target, /* Ensure there is some SVE storage for streaming mode */ if (!target->thread.sve_state) { - sve_alloc(target); + sve_alloc(target, false); if (!target->thread.sve_state) { clear_thread_flag(TIF_SME); ret = -ENOMEM; diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index 6981360d5ecb..06dd20b3c88d 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -308,7 +308,7 @@ static int restore_sve_fpsimd_context(struct user_ctxs *user) fpsimd_flush_task_state(current); /* From now, fpsimd_thread_switch() won't touch thread.sve_state */ - sve_alloc(current); + sve_alloc(current, true); if (!current->thread.sve_state) { clear_thread_flag(TIF_SVE); return -ENOMEM;