mirror of
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2025-09-04 20:19:47 +08:00
6d97af487d
arch_check_user_regs() is used at the moment to verify that struct pt_regs contains valid values when entering the kernel from userspace. s390 needs a place in the generic entry code to modify a cpu data structure when switching from userspace to kernel mode. As arch_check_user_regs() is exactly this, rename it to arch_enter_from_user_mode(). When entering the kernel from userspace, arch_check_user_regs() is used to verify that struct pt_regs contains valid values. Note that the NMI codepath doesn't call this function. s390 needs a place in the generic entry code to modify a cpu data structure when switching from userspace to kernel mode. As arch_check_user_regs() is exactly this, rename it to arch_enter_from_user_mode(). Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20220504062351.2954280-2-tmricht@linux.ibm.com Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
99 lines
3.0 KiB
C
99 lines
3.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
|
|
#ifndef _ASM_X86_ENTRY_COMMON_H
|
|
#define _ASM_X86_ENTRY_COMMON_H
|
|
|
|
#include <linux/randomize_kstack.h>
|
|
#include <linux/user-return-notifier.h>
|
|
|
|
#include <asm/nospec-branch.h>
|
|
#include <asm/io_bitmap.h>
|
|
#include <asm/fpu/api.h>
|
|
|
|
/* Check that the stack and regs on entry from user mode are sane. */
|
|
static __always_inline void arch_enter_from_user_mode(struct pt_regs *regs)
|
|
{
|
|
if (IS_ENABLED(CONFIG_DEBUG_ENTRY)) {
|
|
/*
|
|
* Make sure that the entry code gave us a sensible EFLAGS
|
|
* register. Native because we want to check the actual CPU
|
|
* state, not the interrupt state as imagined by Xen.
|
|
*/
|
|
unsigned long flags = native_save_fl();
|
|
unsigned long mask = X86_EFLAGS_DF | X86_EFLAGS_NT;
|
|
|
|
/*
|
|
* For !SMAP hardware we patch out CLAC on entry.
|
|
*/
|
|
if (boot_cpu_has(X86_FEATURE_SMAP) ||
|
|
(IS_ENABLED(CONFIG_64BIT) && boot_cpu_has(X86_FEATURE_XENPV)))
|
|
mask |= X86_EFLAGS_AC;
|
|
|
|
WARN_ON_ONCE(flags & mask);
|
|
|
|
/* We think we came from user mode. Make sure pt_regs agrees. */
|
|
WARN_ON_ONCE(!user_mode(regs));
|
|
|
|
/*
|
|
* All entries from user mode (except #DF) should be on the
|
|
* normal thread stack and should have user pt_regs in the
|
|
* correct location.
|
|
*/
|
|
WARN_ON_ONCE(!on_thread_stack());
|
|
WARN_ON_ONCE(regs != task_pt_regs(current));
|
|
}
|
|
}
|
|
#define arch_enter_from_user_mode arch_enter_from_user_mode
|
|
|
|
static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs,
|
|
unsigned long ti_work)
|
|
{
|
|
if (ti_work & _TIF_USER_RETURN_NOTIFY)
|
|
fire_user_return_notifiers();
|
|
|
|
if (unlikely(ti_work & _TIF_IO_BITMAP))
|
|
tss_update_io_bitmap();
|
|
|
|
fpregs_assert_state_consistent();
|
|
if (unlikely(ti_work & _TIF_NEED_FPU_LOAD))
|
|
switch_fpu_return();
|
|
|
|
#ifdef CONFIG_COMPAT
|
|
/*
|
|
* Compat syscalls set TS_COMPAT. Make sure we clear it before
|
|
* returning to user mode. We need to clear it *after* signal
|
|
* handling, because syscall restart has a fixup for compat
|
|
* syscalls. The fixup is exercised by the ptrace_syscall_32
|
|
* selftest.
|
|
*
|
|
* We also need to clear TS_REGS_POKED_I386: the 32-bit tracer
|
|
* special case only applies after poking regs and before the
|
|
* very next return to user mode.
|
|
*/
|
|
current_thread_info()->status &= ~(TS_COMPAT | TS_I386_REGS_POKED);
|
|
#endif
|
|
|
|
/*
|
|
* Ultimately, this value will get limited by KSTACK_OFFSET_MAX(),
|
|
* but not enough for x86 stack utilization comfort. To keep
|
|
* reasonable stack head room, reduce the maximum offset to 8 bits.
|
|
*
|
|
* The actual entropy will be further reduced by the compiler when
|
|
* applying stack alignment constraints (see cc_stack_align4/8 in
|
|
* arch/x86/Makefile), which will remove the 3 (x86_64) or 2 (ia32)
|
|
* low bits from any entropy chosen here.
|
|
*
|
|
* Therefore, final stack offset entropy will be 5 (x86_64) or
|
|
* 6 (ia32) bits.
|
|
*/
|
|
choose_random_kstack_offset(rdtsc() & 0xFF);
|
|
}
|
|
#define arch_exit_to_user_mode_prepare arch_exit_to_user_mode_prepare
|
|
|
|
static __always_inline void arch_exit_to_user_mode(void)
|
|
{
|
|
mds_user_clear_cpu_buffers();
|
|
}
|
|
#define arch_exit_to_user_mode arch_exit_to_user_mode
|
|
|
|
#endif
|