arm64/sve: Core task context handling

[thirdparty/kernel/stable.git] / arch / arm64 / kernel / process.c

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 2dc0f84822109b542e21d71deba5206b624f4fc6..b2adcce7bc18e628c924d009ba38190cb1bff951 100644 (file)
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -49,6 +49,7 @@
 #include <linux/notifier.h>
 #include <trace/events/power.h>
 #include <linux/percpu.h>
+#include <linux/thread_info.h>
 
 #include <asm/alternative.h>
 #include <asm/compat.h>
@@ -170,6 +171,39 @@ void machine_restart(char *cmd)
        while (1);
 }
 
+static void print_pstate(struct pt_regs *regs)
+{
+       u64 pstate = regs->pstate;
+
+       if (compat_user_mode(regs)) {
+               printk("pstate: %08llx (%c%c%c%c %c %s %s %c%c%c)\n",
+                       pstate,
+                       pstate & COMPAT_PSR_N_BIT ? 'N' : 'n',
+                       pstate & COMPAT_PSR_Z_BIT ? 'Z' : 'z',
+                       pstate & COMPAT_PSR_C_BIT ? 'C' : 'c',
+                       pstate & COMPAT_PSR_V_BIT ? 'V' : 'v',
+                       pstate & COMPAT_PSR_Q_BIT ? 'Q' : 'q',
+                       pstate & COMPAT_PSR_T_BIT ? "T32" : "A32",
+                       pstate & COMPAT_PSR_E_BIT ? "BE" : "LE",
+                       pstate & COMPAT_PSR_A_BIT ? 'A' : 'a',
+                       pstate & COMPAT_PSR_I_BIT ? 'I' : 'i',
+                       pstate & COMPAT_PSR_F_BIT ? 'F' : 'f');
+       } else {
+               printk("pstate: %08llx (%c%c%c%c %c%c%c%c %cPAN %cUAO)\n",
+                       pstate,
+                       pstate & PSR_N_BIT ? 'N' : 'n',
+                       pstate & PSR_Z_BIT ? 'Z' : 'z',
+                       pstate & PSR_C_BIT ? 'C' : 'c',
+                       pstate & PSR_V_BIT ? 'V' : 'v',
+                       pstate & PSR_D_BIT ? 'D' : 'd',
+                       pstate & PSR_A_BIT ? 'A' : 'a',
+                       pstate & PSR_I_BIT ? 'I' : 'i',
+                       pstate & PSR_F_BIT ? 'F' : 'f',
+                       pstate & PSR_PAN_BIT ? '+' : '-',
+                       pstate & PSR_UAO_BIT ? '+' : '-');
+       }
+}
+
 void __show_regs(struct pt_regs *regs)
 {
        int i, top_reg;
@@ -186,10 +220,9 @@ void __show_regs(struct pt_regs *regs)
        }
 
        show_regs_print_info(KERN_DEFAULT);
-       print_symbol("PC is at %s\n", instruction_pointer(regs));
-       print_symbol("LR is at %s\n", lr);
-       printk("pc : [<%016llx>] lr : [<%016llx>] pstate: %08llx\n",
-              regs->pc, lr, regs->pstate);
+       print_pstate(regs);
+       print_symbol("pc : %s\n", regs->pc);
+       print_symbol("lr : %s\n", lr);
        printk("sp : %016llx\n", sp);
 
        i = top_reg;
@@ -241,11 +274,27 @@ void release_thread(struct task_struct *dead_task)
 {
 }
 
+void arch_release_task_struct(struct task_struct *tsk)
+{
+       fpsimd_release_task(tsk);
+}
+
+/*
+ * src and dst may temporarily have aliased sve_state after task_struct
+ * is copied.  We cannot fix this properly here, because src may have
+ * live SVE state and dst's thread_info may not exist yet, so tweaking
+ * either src's or dst's TIF_SVE is not safe.
+ *
+ * The unaliasing is done in copy_thread() instead.  This works because
+ * dst is not schedulable or traceable until both of these functions
+ * have been called.
+ */
 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 {
        if (current->mm)
                fpsimd_preserve_current_state();
        *dst = *src;
+
        return 0;
 }
 
@@ -258,6 +307,13 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start,
 
        memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context));
 
+       /*
+        * Unalias p->thread.sve_state (if any) from the parent task
+        * and disable discard SVE state for p:
+        */
+       clear_tsk_thread_flag(p, TIF_SVE);
+       p->thread.sve_state = NULL;
+
        if (likely(!(p->flags & PF_KTHREAD))) {
                *childregs = *current_pt_regs();
                childregs->regs[0] = 0;