/*
* Save the fpu, extended register state to the user signal frame.
*
* 'buf_fx' is the 64-byte aligned pointer at which the [f|fx|x]save
* state is copied.
* 'buf' points to the 'buf_fx' or to the fsave header followed by 'buf_fx'.
*
* buf == buf_fx for 64-bit frames and 32-bit fsave frame.
* buf != buf_fx for 32-bit frames with fxstate.
*
* If the fpu, extended register state is live, save the state directly
* to the user frame pointed by the aligned pointer 'buf_fx'. Otherwise,
* copy the thread's fpu state to the user frame starting at 'buf_fx'.
*
* If this is a 32-bit frame with fxstate, put a fsave header before
* the aligned state at 'buf_fx'.
*
* For [f]xsave state, update the SW reserved fields in the [f]xsave frame
* indicating the absence/presence of the extended state to the user.
*/
int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
{
struct xregs_state *xsave = ¤t->thread.fpu.state.xsave;
struct task_struct *tsk = current;
int ia32_fxstate = (buf != buf_fx);
ia32_fxstate &= (config_enabled(CONFIG_X86_32) ||
config_enabled(CONFIG_IA32_EMULATION));
if (!access_ok(VERIFY_WRITE, buf, size))
return -EACCES;
if (!static_cpu_has(X86_FEATURE_FPU))
return fpregs_soft_get(current, NULL, 0,
sizeof(struct user_i387_ia32_struct), NULL,
(struct _fpstate_ia32 __user *) buf) ? -1 : 1;
if (!config_enabled(CONFIG_L4) && fpregs_active()) {
/* Save the live register state to the user directly. */
if (copy_fpregs_to_sigframe(buf_fx))
return -1;
/* Update the thread's fxstate to save the fsave header. */
if (ia32_fxstate)
copy_fxregs_to_kernel(&tsk->thread.fpu);
} else {
if (config_enabled(CONFIG_L4) && fpregs_active())
fpu__save(&tsk->thread.fpu);
fpstate_sanitize_xstate(&tsk->thread.fpu);
if (__copy_to_user(buf_fx, xsave, xstate_size))
return -1;
}
/* Save the fsave header for the 32-bit frames. */
if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf))
return -1;
if (use_fxsr() && save_xstate_epilog(buf_fx, ia32_fxstate))
return -1;
return 0;
}
/*
* Save the fpu, extended register state to the user signal frame.
*
* 'buf_fx' is the 64-byte aligned pointer at which the [f|fx|x]save
* state is copied.
* 'buf' points to the 'buf_fx' or to the fsave header followed by 'buf_fx'.
*
* buf == buf_fx for 64-bit frames and 32-bit fsave frame.
* buf != buf_fx for 32-bit frames with fxstate.
*
* If the fpu, extended register state is live, save the state directly
* to the user frame pointed by the aligned pointer 'buf_fx'. Otherwise,
* copy the thread's fpu state to the user frame starting at 'buf_fx'.
*
* If this is a 32-bit frame with fxstate, put a fsave header before
* the aligned state at 'buf_fx'.
*
* For [f]xsave state, update the SW reserved fields in the [f]xsave frame
* indicating the absence/presence of the extended state to the user.
*/
int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
{
struct xregs_state *xsave = ¤t->thread.fpu.state.xsave;
struct task_struct *tsk = current;
int ia32_fxstate = (buf != buf_fx);
ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) ||
IS_ENABLED(CONFIG_IA32_EMULATION));
if (!access_ok(VERIFY_WRITE, buf, size))
return -EACCES;
if (!static_cpu_has(X86_FEATURE_FPU))
return fpregs_soft_get(current, NULL, 0,
sizeof(struct user_i387_ia32_struct), NULL,
(struct _fpstate_32 __user *) buf) ? -1 : 1;
if (fpregs_active() || using_compacted_format()) {
/* Save the live register state to the user directly. */
if (copy_fpregs_to_sigframe(buf_fx))
return -1;
/* Update the thread's fxstate to save the fsave header. */
if (ia32_fxstate)
copy_fxregs_to_kernel(&tsk->thread.fpu);
} else {
/*
* It is a *bug* if kernel uses compacted-format for xsave
* area and we copy it out directly to a signal frame. It
* should have been handled above by saving the registers
* directly.
*/
if (boot_cpu_has(X86_FEATURE_XSAVES)) {
WARN_ONCE(1, "x86/fpu: saving compacted-format xsave area to a signal frame!\n");
return -1;
}
fpstate_sanitize_xstate(&tsk->thread.fpu);
if (__copy_to_user(buf_fx, xsave, fpu_user_xstate_size))
return -1;
}
/* Save the fsave header for the 32-bit frames. */
if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf))
return -1;
if (use_fxsr() && save_xstate_epilog(buf_fx, ia32_fxstate))
return -1;
return 0;
}
/*H:040
* This is the i386-specific code to setup and run the Guest. Interrupts
* are disabled: we own the CPU.
*/
void lguest_arch_run_guest(struct lg_cpu *cpu)
{
/*
* SYSENTER is an optimized way of doing system calls. We can't allow
* it because it always jumps to privilege level 0. A normal Guest
* won't try it because we don't advertise it in CPUID, but a malicious
* Guest (or malicious Guest userspace program) could, so we tell the
* CPU to disable it before running the Guest.
*/
if (boot_cpu_has(X86_FEATURE_SEP))
wrmsr(MSR_IA32_SYSENTER_CS, 0, 0);
/*
* Now we actually run the Guest. It will return when something
* interesting happens, and we can examine its registers to see what it
* was doing.
*/
run_guest_once(cpu, lguest_pages(raw_smp_processor_id()));
/*
* Note that the "regs" structure contains two extra entries which are
* not really registers: a trap number which says what interrupt or
* trap made the switcher code come back, and an error code which some
* traps set.
*/
/* Restore SYSENTER if it's supposed to be on. */
if (boot_cpu_has(X86_FEATURE_SEP))
wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
/*
* If the Guest page faulted, then the cr2 register will tell us the
* bad virtual address. We have to grab this now, because once we
* re-enable interrupts an interrupt could fault and thus overwrite
* cr2, or we could even move off to a different CPU.
*/
if (cpu->regs->trapnum == 14)
cpu->arch.last_pagefault = read_cr2();
/*
* Similarly, if we took a trap because the Guest used the FPU,
* we have to restore the FPU it expects to see.
* fpu__restore() may sleep and we may even move off to
* a different CPU. So all the critical stuff should be done
* before this.
*/
else if (cpu->regs->trapnum == 7 && !fpregs_active())
fpu__restore(¤t->thread.fpu);
}
