lkml.org 
[lkml]   [2019]   [May]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 3/4] arm64/mm: Consolidate page fault information capture
Date
This consolidates page fault information capture and move them bit earlier.
While here it also adds an wrapper is_write_abort(). It also saves some
cycles by replacing multiple user_mode() calls into a single one earlier
during the fault.

Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
---
arch/arm64/mm/fault.c | 22 +++++++++++++++-------
1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index da02678..170c71f 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -435,6 +435,11 @@ static bool is_el0_instruction_abort(unsigned int esr)
return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW;
}

+static bool is_write_abort(unsigned int esr)
+{
+ return (esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM);
+}
+
static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
{
@@ -443,6 +448,9 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
vm_fault_t fault, major = 0;
unsigned long vm_flags = VM_READ | VM_WRITE;
unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
+ bool is_user = user_mode(regs);
+ bool is_el0_exec = is_el0_instruction_abort(esr);
+ bool is_write = is_write_abort(esr);

if (notify_page_fault(regs, esr))
return 0;
@@ -454,12 +462,12 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
if (faulthandler_disabled() || !mm)
goto no_context;

- if (user_mode(regs))
+ if (is_user)
mm_flags |= FAULT_FLAG_USER;

- if (is_el0_instruction_abort(esr)) {
+ if (is_el0_exec) {
vm_flags = VM_EXEC;
- } else if ((esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM)) {
+ } else if (is_write) {
vm_flags = VM_WRITE;
mm_flags |= FAULT_FLAG_WRITE;
}
@@ -487,7 +495,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
* we can bug out early if this is from code which shouldn't.
*/
if (!down_read_trylock(&mm->mmap_sem)) {
- if (!user_mode(regs) && !search_exception_tables(regs->pc))
+ if (!is_user && !search_exception_tables(regs->pc))
goto no_context;
retry:
down_read(&mm->mmap_sem);
@@ -498,7 +506,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
*/
might_sleep();
#ifdef CONFIG_DEBUG_VM
- if (!user_mode(regs) && !search_exception_tables(regs->pc)) {
+ if (!is_user && !search_exception_tables(regs->pc)) {
up_read(&mm->mmap_sem);
goto no_context;
}
@@ -516,7 +524,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
* in __lock_page_or_retry in mm/filemap.c.
*/
if (fatal_signal_pending(current)) {
- if (!user_mode(regs))
+ if (!is_user)
goto no_context;
return 0;
}
@@ -561,7 +569,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
* If we are in kernel mode at this point, we have no context to
* handle this fault with.
*/
- if (!user_mode(regs))
+ if (!is_user)
goto no_context;

if (fault & VM_FAULT_OOM) {
--
2.7.4
\
 
 \ /
  Last update: 2019-05-29 14:35    [W:0.082 / U:1.292 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site