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x86/fault: Remove sw_error_code 

All of the fault handling code now corrently checks user_mode(regs)
as needed, and nothing depends on the X86_PF_USER bit being munged.
Get rid of the sw_error code and use hw_error_code everywhere.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/078f5b8ae6e8c79ff8ee7345b5c476c45003e5ac.1542841400.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2018-11-21 15:11:22 -08:00 committed by Ingo Molnar
parent 1ad33f5aec
commit 0ed32f1aa6
1 changed files with 11 additions and 39 deletions
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50
arch/x86/mm/fault.c
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@ -1217,7 +1217,6 @@ void do_user_addr_fault(struct pt_regs *regs,
unsigned long hw_error_code,
unsigned long address)
{
unsigned long sw_error_code;
struct vm_area_struct *vma;
struct task_struct *tsk;
struct mm_struct *mm;
@ -1262,13 +1261,6 @@ void do_user_addr_fault(struct pt_regs *regs,
return;
}
/*
* hw_error_code is literally the "page fault error code" passed to
* the kernel directly from the hardware. But, we will shortly be
* modifying it in software, so give it a new name.
*/
sw_error_code = hw_error_code;
/*
* It's safe to allow irq's after cr2 has been saved and the
* vmalloc fault has been handled.
@ -1278,26 +1270,6 @@ void do_user_addr_fault(struct pt_regs *regs,
*/
if (user_mode(regs)) {
local_irq_enable();
/*
* Up to this point, X86_PF_USER set in hw_error_code
* indicated a user-mode access. But, after this,
* X86_PF_USER in sw_error_code will indicate either
* that, *or* an implicit kernel(supervisor)-mode access
* which originated from user mode.
*/
if (!(hw_error_code & X86_PF_USER)) {
/*
* The CPU was in user mode, but the CPU says
* the fault was not a user-mode access.
* Must be an implicit kernel-mode access,
* which we do not expect to happen in the
* user address space.
*/
pr_warn_once("kernel-mode error from user-mode: %lx\n",
hw_error_code);
sw_error_code |= X86_PF_USER;
}
flags |= FAULT_FLAG_USER;
} else {
if (regs->flags & X86_EFLAGS_IF)
@ -1306,9 +1278,9 @@ void do_user_addr_fault(struct pt_regs *regs,
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
if (sw_error_code & X86_PF_WRITE)
if (hw_error_code & X86_PF_WRITE)
flags |= FAULT_FLAG_WRITE;
if (sw_error_code & X86_PF_INSTR)
if (hw_error_code & X86_PF_INSTR)
flags |= FAULT_FLAG_INSTRUCTION;
#ifdef CONFIG_X86_64
@ -1321,7 +1293,7 @@ void do_user_addr_fault(struct pt_regs *regs,
* The vsyscall page does not have a "real" VMA, so do this
* emulation before we go searching for VMAs.
*/
if ((sw_error_code & X86_PF_INSTR) && is_vsyscall_vaddr(address)) {
if ((hw_error_code & X86_PF_INSTR) && is_vsyscall_vaddr(address)) {
if (emulate_vsyscall(regs, address))
return;
}
@ -1345,7 +1317,7 @@ void do_user_addr_fault(struct pt_regs *regs,
* Fault from code in kernel from
* which we do not expect faults.
*/
bad_area_nosemaphore(regs, sw_error_code, address);
bad_area_nosemaphore(regs, hw_error_code, address);
return;
}
retry:
@ -1361,17 +1333,17 @@ void do_user_addr_fault(struct pt_regs *regs,
vma = find_vma(mm, address);
if (unlikely(!vma)) {
bad_area(regs, sw_error_code, address);
bad_area(regs, hw_error_code, address);
return;
}
if (likely(vma->vm_start <= address))
goto good_area;
if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) {
bad_area(regs, sw_error_code, address);
bad_area(regs, hw_error_code, address);
return;
}
if (unlikely(expand_stack(vma, address))) {
bad_area(regs, sw_error_code, address);
bad_area(regs, hw_error_code, address);
return;
}
@ -1380,8 +1352,8 @@ void do_user_addr_fault(struct pt_regs *regs,
* we can handle it..
*/
good_area:
if (unlikely(access_error(sw_error_code, vma))) {
bad_area_access_error(regs, sw_error_code, address, vma);
if (unlikely(access_error(hw_error_code, vma))) {
bad_area_access_error(regs, hw_error_code, address, vma);
return;
}
@ -1420,13 +1392,13 @@ void do_user_addr_fault(struct pt_regs *regs,
return;
/* Not returning to user mode? Handle exceptions or die: */
no_context(regs, sw_error_code, address, SIGBUS, BUS_ADRERR);
no_context(regs, hw_error_code, address, SIGBUS, BUS_ADRERR);
return;
}
up_read(&mm->mmap_sem);
if (unlikely(fault & VM_FAULT_ERROR)) {
mm_fault_error(regs, sw_error_code, address, fault);
mm_fault_error(regs, hw_error_code, address, fault);
return;
}