@@ -108,6 +108,45 @@ static int store_updates_sp(struct pt_regs *regs)
* do_page_fault error handling helpers
*/
+static int
+__bad_area_nosemaphore(struct pt_regs *regs, unsigned long address, int si_code)
+{
+ /*
+ * If we are in kernel mode, bail out with a SEGV, this will
+ * be caught by the assembly which will restore the non-volatile
+ * registers before calling bad_page_fault()
+ */
+ if (!user_mode(regs))
+ return SIGSEGV;
+
+ _exception(SIGSEGV, regs, si_code, address);
+
+ return 0;
+}
+
+static noinline int bad_area_nosemaphore(struct pt_regs *regs, unsigned long address)
+{
+ return __bad_area_nosemaphore(regs, address, SEGV_MAPERR);
+}
+
+static int __bad_area(struct pt_regs *regs, unsigned long address, int si_code)
+{
+ struct mm_struct *mm = current->mm;
+
+ /*
+ * Something tried to access memory that isn't in our memory map..
+ * Fix it, but check if it's kernel or user first..
+ */
+ up_read(&mm->mmap_sem);
+
+ return __bad_area_nosemaphore(regs, address, si_code);
+}
+
+static noinline int bad_area(struct pt_regs *regs, unsigned long address)
+{
+ return __bad_area(regs, address, SEGV_MAPERR);
+}
+
#define MM_FAULT_RETURN 0
#define MM_FAULT_CONTINUE -1
#define MM_FAULT_ERR(sig) (sig)
@@ -231,7 +270,6 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
struct vm_area_struct * vma;
struct mm_struct *mm = current->mm;
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
- int code = SEGV_MAPERR;
int is_exec = TRAP(regs) == 0x400;
int is_user = user_mode(regs);
int is_write = page_fault_is_write(error_code);
@@ -317,7 +355,7 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
*/
if (!down_read_trylock(&mm->mmap_sem)) {
if (!is_user && !search_exception_tables(regs->nip))
- goto bad_area_nosemaphore;
+ return bad_area_nosemaphore(regs, address);
retry:
down_read(&mm->mmap_sem);
@@ -332,11 +370,11 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
vma = find_vma(mm, address);
if (!vma)
- goto bad_area;
+ return bad_area(regs, address);
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
- goto bad_area;
+ return bad_area(regs, address);
/*
* N.B. The POWER/Open ABI allows programs to access up to
@@ -351,7 +389,7 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
/* get user regs even if this fault is in kernel mode */
struct pt_regs *uregs = current->thread.regs;
if (uregs == NULL)
- goto bad_area;
+ return bad_area(regs, address);
/*
* A user-mode access to an address a long way below
@@ -366,14 +404,12 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
* expand the stack rather than segfaulting.
*/
if (address + 2048 < uregs->gpr[1] && !store_update_sp)
- goto bad_area;
+ return bad_area(regs, address);
}
if (expand_stack(vma, address))
- goto bad_area;
+ return bad_area(regs, address);
good_area:
- code = SEGV_ACCERR;
-
if (is_exec) {
/*
* Allow execution from readable areas if the MMU does not
@@ -388,16 +424,16 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
if (!(vma->vm_flags & VM_EXEC) &&
(cpu_has_feature(CPU_FTR_NOEXECUTE) ||
!(vma->vm_flags & (VM_READ | VM_WRITE))))
- goto bad_area;
+ return bad_area(regs, address);
/* a write */
} else if (is_write) {
if (!(vma->vm_flags & VM_WRITE))
- goto bad_area;
+ return bad_area(regs, address);
flags |= FAULT_FLAG_WRITE;
/* a read */
} else {
if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
- goto bad_area;
+ return bad_area(regs, address);
}
#ifdef CONFIG_PPC_STD_MMU
/*
@@ -462,11 +498,10 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
if (unlikely(fault & (VM_FAULT_RETRY|VM_FAULT_ERROR))) {
if (fault & VM_FAULT_SIGSEGV)
- goto bad_area_nosemaphore;
+ return bad_area_nosemaphore(regs, address);
rc = mm_fault_error(regs, address, fault);
if (rc >= MM_FAULT_RETURN)
return rc;
- rc = 0;
}
/*
@@ -492,20 +527,7 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
regs, address);
}
-
- return rc;
-
-bad_area:
- up_read(&mm->mmap_sem);
-
-bad_area_nosemaphore:
- /* User mode accesses cause a SIGSEGV */
- if (is_user) {
- _exception(SIGSEGV, regs, code, address);
- return 0;
- }
-
- return SIGSEGV;
+ return 0;
}
NOKPROBE_SYMBOL(__do_page_fault);
Instead of goto labels, instead call those functions and return. This gets us closer to x86 and allows us to shring do_page_fault() even more. The main difference with x86 is that those function return a value which we then return from do_page_fault(). That value is our return value from do_page_fault() which we use to generate kernel faults. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> --- arch/powerpc/mm/fault.c | 78 +++++++++++++++++++++++++++++++------------------ 1 file changed, 50 insertions(+), 28 deletions(-)