cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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fpu.c (1821B)


      1// SPDX-License-Identifier: GPL-2.0
      2#include <linux/sched/signal.h>
      3#include <linux/sched/task.h>
      4#include <linux/sched/task_stack.h>
      5#include <linux/slab.h>
      6#include <asm/processor.h>
      7#include <asm/fpu.h>
      8#include <asm/traps.h>
      9#include <asm/ptrace.h>
     10
     11int init_fpu(struct task_struct *tsk)
     12{
     13	if (tsk_used_math(tsk)) {
     14		if ((boot_cpu_data.flags & CPU_HAS_FPU) && tsk == current)
     15			unlazy_fpu(tsk, task_pt_regs(tsk));
     16		return 0;
     17	}
     18
     19	/*
     20	 * Memory allocation at the first usage of the FPU and other state.
     21	 */
     22	if (!tsk->thread.xstate) {
     23		tsk->thread.xstate = kmem_cache_alloc(task_xstate_cachep,
     24						      GFP_KERNEL);
     25		if (!tsk->thread.xstate)
     26			return -ENOMEM;
     27	}
     28
     29	if (boot_cpu_data.flags & CPU_HAS_FPU) {
     30		struct sh_fpu_hard_struct *fp = &tsk->thread.xstate->hardfpu;
     31		memset(fp, 0, xstate_size);
     32		fp->fpscr = FPSCR_INIT;
     33	} else {
     34		struct sh_fpu_soft_struct *fp = &tsk->thread.xstate->softfpu;
     35		memset(fp, 0, xstate_size);
     36		fp->fpscr = FPSCR_INIT;
     37	}
     38
     39	set_stopped_child_used_math(tsk);
     40	return 0;
     41}
     42
     43#ifdef CONFIG_SH_FPU
     44void __fpu_state_restore(void)
     45{
     46	struct task_struct *tsk = current;
     47
     48	restore_fpu(tsk);
     49
     50	task_thread_info(tsk)->status |= TS_USEDFPU;
     51	tsk->thread.fpu_counter++;
     52}
     53
     54void fpu_state_restore(struct pt_regs *regs)
     55{
     56	struct task_struct *tsk = current;
     57
     58	if (unlikely(!user_mode(regs))) {
     59		printk(KERN_ERR "BUG: FPU is used in kernel mode.\n");
     60		BUG();
     61		return;
     62	}
     63
     64	if (!tsk_used_math(tsk)) {
     65		int ret;
     66		/*
     67		 * does a slab alloc which can sleep
     68		 */
     69		local_irq_enable();
     70		ret = init_fpu(tsk);
     71		local_irq_disable();
     72		if (ret) {
     73			/*
     74			 * ran out of memory!
     75			 */
     76			force_sig(SIGKILL);
     77			return;
     78		}
     79	}
     80
     81	grab_fpu(regs);
     82
     83	__fpu_state_restore();
     84}
     85
     86BUILD_TRAP_HANDLER(fpu_state_restore)
     87{
     88	TRAP_HANDLER_DECL;
     89
     90	fpu_state_restore(regs);
     91}
     92#endif /* CONFIG_SH_FPU */