175 lines
4.5 KiB
Diff
175 lines
4.5 KiB
Diff
From 39d41edf73a8f9e1e705f64bc12e033d2d03f3d7 Mon Sep 17 00:00:00 2001
|
|
Message-Id: <39d41edf73a8f9e1e705f64bc12e033d2d03f3d7.1596234183.git.zanussi@kernel.org>
|
|
In-Reply-To: <378ee68279f6a7631221f2670a9298620148690d.1596234183.git.zanussi@kernel.org>
|
|
References: <378ee68279f6a7631221f2670a9298620148690d.1596234183.git.zanussi@kernel.org>
|
|
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
|
|
Date: Wed, 25 Jul 2018 14:02:38 +0200
|
|
Subject: [PATCH 212/329] arm64: fpsimd: use preemp_disable in addition to
|
|
local_bh_disable()
|
|
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.135-rt60.tar.xz
|
|
|
|
In v4.16-RT I noticed a number of warnings from task_fpsimd_load(). The
|
|
code disables BH and expects that it is not preemptible. On -RT the
|
|
task remains preemptible but remains the same CPU. This may corrupt the
|
|
content of the SIMD registers if the task is preempted during
|
|
saving/restoring those registers.
|
|
|
|
Add preempt_disable()/enable() to enfore the required semantic on -RT.
|
|
|
|
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
|
|
---
|
|
arch/arm64/kernel/fpsimd.c | 31 +++++++++++++++++++++++++++++--
|
|
1 file changed, 29 insertions(+), 2 deletions(-)
|
|
|
|
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
|
|
index 19c87b52c001..203245dad743 100644
|
|
--- a/arch/arm64/kernel/fpsimd.c
|
|
+++ b/arch/arm64/kernel/fpsimd.c
|
|
@@ -159,6 +159,16 @@ static void sve_free(struct task_struct *task)
|
|
__sve_free(task);
|
|
}
|
|
|
|
+static void *sve_free_atomic(struct task_struct *task)
|
|
+{
|
|
+ void *sve_state = task->thread.sve_state;
|
|
+
|
|
+ WARN_ON(test_tsk_thread_flag(task, TIF_SVE));
|
|
+
|
|
+ task->thread.sve_state = NULL;
|
|
+ return sve_state;
|
|
+}
|
|
+
|
|
/*
|
|
* TIF_SVE controls whether a task can use SVE without trapping while
|
|
* in userspace, and also the way a task's FPSIMD/SVE state is stored
|
|
@@ -549,6 +559,7 @@ int sve_set_vector_length(struct task_struct *task,
|
|
* non-SVE thread.
|
|
*/
|
|
if (task == current) {
|
|
+ preempt_disable();
|
|
local_bh_disable();
|
|
|
|
fpsimd_save();
|
|
@@ -559,8 +570,10 @@ int sve_set_vector_length(struct task_struct *task,
|
|
if (test_and_clear_tsk_thread_flag(task, TIF_SVE))
|
|
sve_to_fpsimd(task);
|
|
|
|
- if (task == current)
|
|
+ if (task == current) {
|
|
local_bh_enable();
|
|
+ preempt_enable();
|
|
+ }
|
|
|
|
/*
|
|
* Force reallocation of task SVE state to the correct size
|
|
@@ -815,6 +828,7 @@ asmlinkage void do_sve_acc(unsigned int esr, struct pt_regs *regs)
|
|
|
|
sve_alloc(current);
|
|
|
|
+ preempt_disable();
|
|
local_bh_disable();
|
|
|
|
fpsimd_save();
|
|
@@ -828,6 +842,7 @@ asmlinkage void do_sve_acc(unsigned int esr, struct pt_regs *regs)
|
|
WARN_ON(1); /* SVE access shouldn't have trapped */
|
|
|
|
local_bh_enable();
|
|
+ preempt_enable();
|
|
}
|
|
|
|
/*
|
|
@@ -894,10 +909,12 @@ void fpsimd_thread_switch(struct task_struct *next)
|
|
void fpsimd_flush_thread(void)
|
|
{
|
|
int vl, supported_vl;
|
|
+ void *mem = NULL;
|
|
|
|
if (!system_supports_fpsimd())
|
|
return;
|
|
|
|
+ preempt_disable();
|
|
local_bh_disable();
|
|
|
|
memset(¤t->thread.uw.fpsimd_state, 0,
|
|
@@ -906,7 +923,7 @@ void fpsimd_flush_thread(void)
|
|
|
|
if (system_supports_sve()) {
|
|
clear_thread_flag(TIF_SVE);
|
|
- sve_free(current);
|
|
+ mem = sve_free_atomic(current);
|
|
|
|
/*
|
|
* Reset the task vector length as required.
|
|
@@ -942,6 +959,8 @@ void fpsimd_flush_thread(void)
|
|
set_thread_flag(TIF_FOREIGN_FPSTATE);
|
|
|
|
local_bh_enable();
|
|
+ preempt_enable();
|
|
+ kfree(mem);
|
|
}
|
|
|
|
/*
|
|
@@ -953,9 +972,11 @@ void fpsimd_preserve_current_state(void)
|
|
if (!system_supports_fpsimd())
|
|
return;
|
|
|
|
+ preempt_disable();
|
|
local_bh_disable();
|
|
fpsimd_save();
|
|
local_bh_enable();
|
|
+ preempt_enable();
|
|
}
|
|
|
|
/*
|
|
@@ -1026,6 +1047,7 @@ void fpsimd_restore_current_state(void)
|
|
return;
|
|
}
|
|
|
|
+ preempt_disable();
|
|
local_bh_disable();
|
|
|
|
if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
|
|
@@ -1034,6 +1056,7 @@ void fpsimd_restore_current_state(void)
|
|
}
|
|
|
|
local_bh_enable();
|
|
+ preempt_enable();
|
|
}
|
|
|
|
/*
|
|
@@ -1046,6 +1069,7 @@ void fpsimd_update_current_state(struct user_fpsimd_state const *state)
|
|
if (WARN_ON(!system_supports_fpsimd()))
|
|
return;
|
|
|
|
+ preempt_disable();
|
|
local_bh_disable();
|
|
|
|
current->thread.uw.fpsimd_state = *state;
|
|
@@ -1058,6 +1082,7 @@ void fpsimd_update_current_state(struct user_fpsimd_state const *state)
|
|
clear_thread_flag(TIF_FOREIGN_FPSTATE);
|
|
|
|
local_bh_enable();
|
|
+ preempt_enable();
|
|
}
|
|
|
|
/*
|
|
@@ -1104,6 +1129,7 @@ void kernel_neon_begin(void)
|
|
|
|
BUG_ON(!may_use_simd());
|
|
|
|
+ preempt_disable();
|
|
local_bh_disable();
|
|
|
|
__this_cpu_write(kernel_neon_busy, true);
|
|
@@ -1117,6 +1143,7 @@ void kernel_neon_begin(void)
|
|
preempt_disable();
|
|
|
|
local_bh_enable();
|
|
+ preempt_enable();
|
|
}
|
|
EXPORT_SYMBOL(kernel_neon_begin);
|
|
|
|
--
|
|
2.17.1
|
|
|