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Message-Id: <20b7d988a4fd029ced32087acec716564277489d.1542667307.git.luto@kernel.org>
Date: Mon, 19 Nov 2018 14:45:33 -0800
From: Andy Lutomirski <luto@...nel.org>
To: x86@...nel.org
Cc: LKML <linux-kernel@...r.kernel.org>,
Yu-cheng Yu <yu-cheng.yu@...el.com>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Peter Zijlstra <peterz@...radead.org>,
Borislav Petkov <bp@...en8.de>,
Andy Lutomirski <luto@...nel.org>
Subject: [PATCH 09/13] 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@...nel.org>
---
arch/x86/mm/fault.c | 52 +++++++++++----------------------------------
1 file changed, 12 insertions(+), 40 deletions(-)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index a6554110ef62..6e18438c367f 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -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:
@@ -1361,13 +1333,13 @@ 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 (user_mode(regs)) {
@@ -1378,12 +1350,12 @@ void do_user_addr_fault(struct pt_regs *regs,
* 32 pointers and then decrements %sp by 65535.)
*/
if (unlikely(address + 65536 + 32 * sizeof(unsigned long) < regs->sp)) {
- 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;
}
@@ -1392,8 +1364,8 @@ 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;
}
@@ -1432,13 +1404,13 @@ 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;
}
--
2.17.2
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