powerpc: Exception hooks for context tracking subsystem
This is the exception hooks for context tracking subsystem, including
data access, program check, single step, instruction breakpoint, machine check,
alignment, fp unavailable, altivec assist, unknown exception, whose handlers
might use RCU.
This patch corresponds to
[PATCH] x86: Exception hooks for userspace RCU extended QS
commit 6ba3c97a38803883c2eee489505796cb0a727122
But after the exception handling moved to generic code, and some changes in
following two commits:
56dd9470d7c8734f055da2a6bac553caf4a468eb
context_tracking: Move exception handling to generic code
6c1e0256fad84a843d915414e4b5973b7443d48d
context_tracking: Restore correct previous context state on exception exit
it is able for exception hooks to use the generic code above instead of a
redundant arch implementation.
Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 229951f..8726779 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -32,6 +32,7 @@
#include <linux/perf_event.h>
#include <linux/magic.h>
#include <linux/ratelimit.h>
+#include <linux/context_tracking.h>
#include <asm/firmware.h>
#include <asm/page.h>
@@ -196,6 +197,7 @@
int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
unsigned long error_code)
{
+ enum ctx_state prev_state = exception_enter();
struct vm_area_struct * vma;
struct mm_struct *mm = current->mm;
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
@@ -204,6 +206,7 @@
int trap = TRAP(regs);
int is_exec = trap == 0x400;
int fault;
+ int rc = 0;
#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
/*
@@ -230,28 +233,30 @@
* look at it
*/
if (error_code & ICSWX_DSI_UCT) {
- int rc = acop_handle_fault(regs, address, error_code);
+ rc = acop_handle_fault(regs, address, error_code);
if (rc)
- return rc;
+ goto bail;
}
#endif /* CONFIG_PPC_ICSWX */
if (notify_page_fault(regs))
- return 0;
+ goto bail;
if (unlikely(debugger_fault_handler(regs)))
- return 0;
+ goto bail;
/* On a kernel SLB miss we can only check for a valid exception entry */
- if (!user_mode(regs) && (address >= TASK_SIZE))
- return SIGSEGV;
+ if (!user_mode(regs) && (address >= TASK_SIZE)) {
+ rc = SIGSEGV;
+ goto bail;
+ }
#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE) || \
defined(CONFIG_PPC_BOOK3S_64))
if (error_code & DSISR_DABRMATCH) {
/* breakpoint match */
do_break(regs, address, error_code);
- return 0;
+ goto bail;
}
#endif
@@ -260,8 +265,10 @@
local_irq_enable();
if (in_atomic() || mm == NULL) {
- if (!user_mode(regs))
- return SIGSEGV;
+ if (!user_mode(regs)) {
+ rc = SIGSEGV;
+ goto bail;
+ }
/* in_atomic() in user mode is really bad,
as is current->mm == NULL. */
printk(KERN_EMERG "Page fault in user mode with "
@@ -417,9 +424,11 @@
*/
fault = handle_mm_fault(mm, vma, address, flags);
if (unlikely(fault & (VM_FAULT_RETRY|VM_FAULT_ERROR))) {
- int rc = mm_fault_error(regs, address, fault);
+ rc = mm_fault_error(regs, address, fault);
if (rc >= MM_FAULT_RETURN)
- return rc;
+ goto bail;
+ else
+ rc = 0;
}
/*
@@ -454,7 +463,7 @@
}
up_read(&mm->mmap_sem);
- return 0;
+ goto bail;
bad_area:
up_read(&mm->mmap_sem);
@@ -463,7 +472,7 @@
/* User mode accesses cause a SIGSEGV */
if (user_mode(regs)) {
_exception(SIGSEGV, regs, code, address);
- return 0;
+ goto bail;
}
if (is_exec && (error_code & DSISR_PROTFAULT))
@@ -471,7 +480,11 @@
" page (%lx) - exploit attempt? (uid: %d)\n",
address, from_kuid(&init_user_ns, current_uid()));
- return SIGSEGV;
+ rc = SIGSEGV;
+
+bail:
+ exception_exit(prev_state);
+ return rc;
}
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 88ac0ee..e303a6d 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -33,6 +33,7 @@
#include <linux/init.h>
#include <linux/signal.h>
#include <linux/memblock.h>
+#include <linux/context_tracking.h>
#include <asm/processor.h>
#include <asm/pgtable.h>
@@ -954,6 +955,7 @@
*/
int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
{
+ enum ctx_state prev_state = exception_enter();
pgd_t *pgdir;
unsigned long vsid;
struct mm_struct *mm;
@@ -973,7 +975,8 @@
mm = current->mm;
if (! mm) {
DBG_LOW(" user region with no mm !\n");
- return 1;
+ rc = 1;
+ goto bail;
}
psize = get_slice_psize(mm, ea);
ssize = user_segment_size(ea);
@@ -992,19 +995,23 @@
/* Not a valid range
* Send the problem up to do_page_fault
*/
- return 1;
+ rc = 1;
+ goto bail;
}
DBG_LOW(" mm=%p, mm->pgdir=%p, vsid=%016lx\n", mm, mm->pgd, vsid);
/* Bad address. */
if (!vsid) {
DBG_LOW("Bad address!\n");
- return 1;
+ rc = 1;
+ goto bail;
}
/* Get pgdir */
pgdir = mm->pgd;
- if (pgdir == NULL)
- return 1;
+ if (pgdir == NULL) {
+ rc = 1;
+ goto bail;
+ }
/* Check CPU locality */
tmp = cpumask_of(smp_processor_id());
@@ -1027,7 +1034,8 @@
ptep = find_linux_pte_or_hugepte(pgdir, ea, &hugeshift);
if (ptep == NULL || !pte_present(*ptep)) {
DBG_LOW(" no PTE !\n");
- return 1;
+ rc = 1;
+ goto bail;
}
/* Add _PAGE_PRESENT to the required access perm */
@@ -1038,13 +1046,16 @@
*/
if (access & ~pte_val(*ptep)) {
DBG_LOW(" no access !\n");
- return 1;
+ rc = 1;
+ goto bail;
}
#ifdef CONFIG_HUGETLB_PAGE
- if (hugeshift)
- return __hash_page_huge(ea, access, vsid, ptep, trap, local,
+ if (hugeshift) {
+ rc = __hash_page_huge(ea, access, vsid, ptep, trap, local,
ssize, hugeshift, psize);
+ goto bail;
+ }
#endif /* CONFIG_HUGETLB_PAGE */
#ifndef CONFIG_PPC_64K_PAGES
@@ -1124,6 +1135,9 @@
pte_val(*(ptep + PTRS_PER_PTE)));
#endif
DBG_LOW(" -> rc=%d\n", rc);
+
+bail:
+ exception_exit(prev_state);
return rc;
}
EXPORT_SYMBOL_GPL(hash_page);
@@ -1259,6 +1273,8 @@
*/
void low_hash_fault(struct pt_regs *regs, unsigned long address, int rc)
{
+ enum ctx_state prev_state = exception_enter();
+
if (user_mode(regs)) {
#ifdef CONFIG_PPC_SUBPAGE_PROT
if (rc == -2)
@@ -1268,6 +1284,8 @@
_exception(SIGBUS, regs, BUS_ADRERR, address);
} else
bad_page_fault(regs, address, SIGBUS);
+
+ exception_exit(prev_state);
}
long hpte_insert_repeating(unsigned long hash, unsigned long vpn,