Skip to content

Commit

Permalink
sh: Support thread fault code encoding.
Browse files Browse the repository at this point in the history 
This provides a simple interface modelled after sparc64/m32r to encode
the error code in the upper byte of thread_info for finer-grained
handling in the page fault path.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
  • Loading branch information
Paul Mundt committed May 14, 2012
1 parent f007688 commit 5a1dc78
Show file tree
Hide file tree
Showing 3 changed files with 78 additions and 47 deletions.
46 changes: 36 additions & 10 deletions arch/sh/include/asm/thread_info.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -10,8 +10,18 @@
* - Incorporating suggestions made by Linus Torvalds and Dave Miller
*/
#ifdef __KERNEL__

#include <asm/page.h>

/*
* Page fault error code bits
*/
#define FAULT_CODE_WRITE (1 << 0) /* write access */
#define FAULT_CODE_INITIAL (1 << 1) /* initial page write */
#define FAULT_CODE_ITLB (1 << 2) /* ITLB miss */
#define FAULT_CODE_PROT (1 << 3) /* protection fault */
#define FAULT_CODE_USER (1 << 4) /* user-mode access */

#ifndef __ASSEMBLY__
#include <asm/processor.h>

Expand Down Expand Up @@ -107,10 +117,13 @@ extern void init_thread_xstate(void);
#endif /* __ASSEMBLY__ */

/*
* thread information flags
* - these are process state flags that various assembly files may need to access
* - pending work-to-be-done flags are in LSW
* - other flags in MSW
* Thread information flags
*
* - Limited to 24 bits, upper byte used for fault code encoding.
*
* - _TIF_ALLWORK_MASK and _TIF_WORK_MASK need to fit within 2 bytes, or
* we blow the tst immediate size constraints and need to fix up
* arch/sh/kernel/entry-common.S.
*/
#define TIF_SYSCALL_TRACE 0 /* syscall trace active */
#define TIF_SIGPENDING 1 /* signal pending */
Expand All @@ -133,12 +146,6 @@ extern void init_thread_xstate(void);
#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)

/*
* _TIF_ALLWORK_MASK and _TIF_WORK_MASK need to fit within 2 bytes, or we
* blow the tst immediate size constraints and need to fix up
* arch/sh/kernel/entry-common.S.
*/

/* work to do in syscall trace */
#define _TIF_WORK_SYSCALL_MASK (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP | \
_TIF_SYSCALL_AUDIT | _TIF_SECCOMP | \
Expand All @@ -165,13 +172,32 @@ extern void init_thread_xstate(void);
#define TS_USEDFPU 0x0002 /* FPU used by this task this quantum */

#ifndef __ASSEMBLY__

#define HAVE_SET_RESTORE_SIGMASK 1
static inline void set_restore_sigmask(void)
{
struct thread_info *ti = current_thread_info();
ti->status |= TS_RESTORE_SIGMASK;
set_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags);
}

#define TI_FLAG_FAULT_CODE_SHIFT 24

/*
* Additional thread flag encoding
*/
static inline void set_thread_fault_code(unsigned int val)
{
struct thread_info *ti = current_thread_info();
ti->flags = (ti->flags & (~0 >> (32 - TI_FLAG_FAULT_CODE_SHIFT)))
| (val << TI_FLAG_FAULT_CODE_SHIFT);
}

static inline unsigned int get_thread_fault_code(void)
{
struct thread_info *ti = current_thread_info();
return ti->flags >> TI_FLAG_FAULT_CODE_SHIFT;
}
#endif /* !__ASSEMBLY__ */

#endif /* __KERNEL__ */
Expand Down
11 changes: 6 additions & 5 deletions arch/sh/kernel/cpu/sh3/entry.S
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@
* arch/sh/kernel/cpu/sh3/entry.S
*
* Copyright (C) 1999, 2000, 2002 Niibe Yutaka
* Copyright (C) 2003 - 2006 Paul Mundt
* Copyright (C) 2003 - 2012 Paul Mundt
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
Expand All @@ -17,6 +17,7 @@
#include <cpu/mmu_context.h>
#include <asm/page.h>
#include <asm/cache.h>
#include <asm/thread_info.h>

! NOTE:
! GNU as (as of 2.9.1) changes bf/s into bt/s and bra, when the address
Expand Down Expand Up @@ -114,22 +115,22 @@ ENTRY(tlb_miss_load)
.align 2
ENTRY(tlb_miss_store)
bra call_handle_tlbmiss
mov #1, r5
mov #FAULT_CODE_WRITE, r5

.align 2
ENTRY(initial_page_write)
bra call_handle_tlbmiss
mov #2, r5
mov #FAULT_CODE_INITIAL, r5

.align 2
ENTRY(tlb_protection_violation_load)
bra call_do_page_fault
mov #0, r5
mov #FAULT_CODE_PROT, r5

.align 2
ENTRY(tlb_protection_violation_store)
bra call_do_page_fault
mov #1, r5
mov #(FAULT_CODE_PROT | FAULT_CODE_WRITE), r5

call_handle_tlbmiss:
mov.l 1f, r0
Expand Down
68 changes: 36 additions & 32 deletions arch/sh/mm/fault_32.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -211,7 +211,7 @@ show_fault_oops(struct pt_regs *regs, unsigned long address)
}

static noinline void
no_context(struct pt_regs *regs, unsigned long writeaccess,
no_context(struct pt_regs *regs, unsigned long error_code,
unsigned long address)
{
/* Are we prepared to handle this kernel fault? */
Expand All @@ -229,13 +229,13 @@ no_context(struct pt_regs *regs, unsigned long writeaccess,

show_fault_oops(regs, address);

die("Oops", regs, writeaccess);
die("Oops", regs, error_code);
bust_spinlocks(0);
do_exit(SIGKILL);
}

static void
__bad_area_nosemaphore(struct pt_regs *regs, unsigned long writeaccess,
__bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
unsigned long address, int si_code)
{
struct task_struct *tsk = current;
Expand All @@ -252,18 +252,18 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long writeaccess,
return;
}

no_context(regs, writeaccess, address);
no_context(regs, error_code, address);
}

static noinline void
bad_area_nosemaphore(struct pt_regs *regs, unsigned long writeaccess,
bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
unsigned long address)
{
__bad_area_nosemaphore(regs, writeaccess, address, SEGV_MAPERR);
__bad_area_nosemaphore(regs, error_code, address, SEGV_MAPERR);
}

static void
__bad_area(struct pt_regs *regs, unsigned long writeaccess,
__bad_area(struct pt_regs *regs, unsigned long error_code,
unsigned long address, int si_code)
{
struct mm_struct *mm = current->mm;
Expand All @@ -274,20 +274,20 @@ __bad_area(struct pt_regs *regs, unsigned long writeaccess,
*/
up_read(&mm->mmap_sem);

__bad_area_nosemaphore(regs, writeaccess, address, si_code);
__bad_area_nosemaphore(regs, error_code, address, si_code);
}

static noinline void
bad_area(struct pt_regs *regs, unsigned long writeaccess, unsigned long address)
bad_area(struct pt_regs *regs, unsigned long error_code, unsigned long address)
{
__bad_area(regs, writeaccess, address, SEGV_MAPERR);
__bad_area(regs, error_code, address, SEGV_MAPERR);
}

static noinline void
bad_area_access_error(struct pt_regs *regs, unsigned long writeaccess,
bad_area_access_error(struct pt_regs *regs, unsigned long error_code,
unsigned long address)
{
__bad_area(regs, writeaccess, address, SEGV_ACCERR);
__bad_area(regs, error_code, address, SEGV_ACCERR);
}

static void out_of_memory(void)
Expand All @@ -302,7 +302,7 @@ static void out_of_memory(void)
}

static void
do_sigbus(struct pt_regs *regs, unsigned long writeaccess, unsigned long address)
do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address)
{
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
Expand All @@ -311,13 +311,13 @@ do_sigbus(struct pt_regs *regs, unsigned long writeaccess, unsigned long address

/* Kernel mode? Handle exceptions or die: */
if (!user_mode(regs))
no_context(regs, writeaccess, address);
no_context(regs, error_code, address);

force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);
}

static noinline int
mm_fault_error(struct pt_regs *regs, unsigned long writeaccess,
mm_fault_error(struct pt_regs *regs, unsigned long error_code,
unsigned long address, unsigned int fault)
{
/*
Expand All @@ -328,7 +328,7 @@ mm_fault_error(struct pt_regs *regs, unsigned long writeaccess,
if (!(fault & VM_FAULT_RETRY))
up_read(&current->mm->mmap_sem);
if (!user_mode(regs))
no_context(regs, writeaccess, address);
no_context(regs, error_code, address);
return 1;
}

Expand All @@ -339,14 +339,14 @@ mm_fault_error(struct pt_regs *regs, unsigned long writeaccess,
/* Kernel mode? Handle exceptions or die: */
if (!user_mode(regs)) {
up_read(&current->mm->mmap_sem);
no_context(regs, writeaccess, address);
no_context(regs, error_code, address);
return 1;
}

out_of_memory();
} else {
if (fault & VM_FAULT_SIGBUS)
do_sigbus(regs, writeaccess, address);
do_sigbus(regs, error_code, address);
else
BUG();
}
Expand Down Expand Up @@ -381,16 +381,17 @@ static int fault_in_kernel_space(unsigned long address)
* routines.
*/
asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
unsigned long writeaccess,
unsigned long error_code,
unsigned long address)
{
unsigned long vec;
struct task_struct *tsk;
struct mm_struct *mm;
struct vm_area_struct * vma;
int fault;
int write = error_code & FAULT_CODE_WRITE;
unsigned int flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
(writeaccess ? FAULT_FLAG_WRITE : 0));
(write ? FAULT_FLAG_WRITE : 0));

tsk = current;
mm = tsk->mm;
Expand All @@ -411,7 +412,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
if (notify_page_fault(regs, vec))
return;

bad_area_nosemaphore(regs, writeaccess, address);
bad_area_nosemaphore(regs, error_code, address);
return;
}

Expand All @@ -429,7 +430,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
* in an atomic region then we must not take the fault:
*/
if (unlikely(in_atomic() || !mm)) {
bad_area_nosemaphore(regs, writeaccess, address);
bad_area_nosemaphore(regs, error_code, address);
return;
}

Expand All @@ -438,17 +439,17 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,

vma = find_vma(mm, address);
if (unlikely(!vma)) {
bad_area(regs, writeaccess, address);
bad_area(regs, error_code, address);
return;
}
if (likely(vma->vm_start <= address))
goto good_area;
if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) {
bad_area(regs, writeaccess, address);
bad_area(regs, error_code, address);
return;
}
if (unlikely(expand_stack(vma, address))) {
bad_area(regs, writeaccess, address);
bad_area(regs, error_code, address);
return;
}

Expand All @@ -457,11 +458,13 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
* we can handle it..
*/
good_area:
if (unlikely(access_error(writeaccess, vma))) {
bad_area_access_error(regs, writeaccess, address);
if (unlikely(access_error(error_code, vma))) {
bad_area_access_error(regs, error_code, address);
return;
}

set_thread_fault_code(error_code);

/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
Expand All @@ -470,7 +473,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
fault = handle_mm_fault(mm, vma, address, flags);

if (unlikely(fault & (VM_FAULT_RETRY | VM_FAULT_ERROR)))
if (mm_fault_error(regs, writeaccess, address, fault))
if (mm_fault_error(regs, error_code, address, fault))
return;

if (flags & FAULT_FLAG_ALLOW_RETRY) {
Expand Down Expand Up @@ -502,7 +505,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
* Called with interrupts disabled.
*/
asmlinkage int __kprobes
handle_tlbmiss(struct pt_regs *regs, unsigned long writeaccess,
handle_tlbmiss(struct pt_regs *regs, unsigned long error_code,
unsigned long address)
{
pgd_t *pgd;
Expand Down Expand Up @@ -535,10 +538,10 @@ handle_tlbmiss(struct pt_regs *regs, unsigned long writeaccess,
entry = *pte;
if (unlikely(pte_none(entry) || pte_not_present(entry)))
return 1;
if (unlikely(writeaccess && !pte_write(entry)))
if (unlikely(error_code && !pte_write(entry)))
return 1;

if (writeaccess)
if (error_code)
entry = pte_mkdirty(entry);
entry = pte_mkyoung(entry);

Expand All @@ -550,10 +553,11 @@ handle_tlbmiss(struct pt_regs *regs, unsigned long writeaccess,
* the case of an initial page write exception, so we need to
* flush it in order to avoid potential TLB entry duplication.
*/
if (writeaccess == 2)
if (error_code == FAULT_CODE_INITIAL)
local_flush_tlb_one(get_asid(), address & PAGE_MASK);
#endif

set_thread_fault_code(error_code);
update_mmu_cache(NULL, address, pte);

return 0;
Expand Down

0 comments on commit 5a1dc78

Please sign in to comment.