[RFC PATCH v2 6/6] powerpc: Use generic code for exception handling

From: Li Zhong
Date: Fri Mar 29 2013 - 06:01:14 EST

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 this patch to replace the implementation in arch code
with the generic code in above commits.

Signed-off-by: Li Zhong <zhong@xxxxxxxxxxxxxxxxxx>
---
arch/powerpc/include/asm/context_tracking.h | 29 ---------------
arch/powerpc/kernel/exceptions-64s.S | 4 +--
arch/powerpc/kernel/traps.c | 42 +++++++++++++---------
arch/powerpc/mm/fault.c | 7 ++--
arch/powerpc/mm/hash_utils_64.c | 51 ++++++++++++++-------------
5 files changed, 57 insertions(+), 76 deletions(-)

diff --git a/arch/powerpc/include/asm/context_tracking.h b/arch/powerpc/include/asm/context_tracking.h
index 4da287e..b6f5a33 100644
--- a/arch/powerpc/include/asm/context_tracking.h
+++ b/arch/powerpc/include/asm/context_tracking.h
@@ -1,39 +1,10 @@
#ifndef _ASM_POWERPC_CONTEXT_TRACKING_H
#define _ASM_POWERPC_CONTEXT_TRACKING_H

-#ifndef __ASSEMBLY__
-#include <linux/context_tracking.h>
-#include <asm/ptrace.h>
-
-/*
- * temporarily defined to avoid potential conflicts with the common
- * implementation, these will be removed by a later patch after the common
- * code enters powerpc tree
- */
-#define exception_enter __exception_enter
-#define exception_exit __exception_exit
-
-static inline void __exception_enter(struct pt_regs *regs)
-{
- user_exit();
-}
-
-static inline void __exception_exit(struct pt_regs *regs)
-{
-#ifdef CONFIG_CONTEXT_TRACKING
- if (user_mode(regs))
- user_enter();
-#endif
-}
-
-#else /* __ASSEMBLY__ */
-
#ifdef CONFIG_CONTEXT_TRACKING
#define SCHEDULE_USER bl .schedule_user
#else
#define SCHEDULE_USER bl .schedule
#endif

-#endif /* !__ASSEMBLY__ */
-
#endif
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 6d82f4f..a8a5361 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1368,17 +1368,15 @@ END_MMU_FTR_SECTION_IFCLR(MMU_FTR_SLB)
rlwimi r4,r0,32-13,30,30 /* becomes _PAGE_USER access bit */
ori r4,r4,1 /* add _PAGE_PRESENT */
rlwimi r4,r5,22+2,31-2,31-2 /* Set _PAGE_EXEC if trap is 0x400 */
- addi r6,r1,STACK_FRAME_OVERHEAD

/*
* r3 contains the faulting address
* r4 contains the required access permissions
* r5 contains the trap number
- * r6 contains the address of pt_regs
*
* at return r3 = 0 for success, 1 for page fault, negative for error
*/
- bl .hash_page_ct /* build HPTE if possible */
+ bl .hash_page /* build HPTE if possible */
cmpdi r3,0 /* see if hash_page succeeded */

/* Success */
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 6228b6b..1b46c2d9 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -35,6 +35,7 @@
#include <linux/kdebug.h>
#include <linux/debugfs.h>
#include <linux/ratelimit.h>
+#include <linux/context_tracking.h>

#include <asm/emulated_ops.h>
#include <asm/pgtable.h>
@@ -60,7 +61,6 @@
#include <asm/switch_to.h>
#include <asm/tm.h>
#include <asm/debug.h>
-#include <asm/context_tracking.h>

#if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
int (*__debugger)(struct pt_regs *regs) __read_mostly;
@@ -669,8 +669,9 @@ int machine_check_generic(struct pt_regs *regs)
void machine_check_exception(struct pt_regs *regs)
{
int recover = 0;
+ enum ctx_state prev_state;

- exception_enter(regs);
+ prev_state = exception_enter();

__get_cpu_var(irq_stat).mce_exceptions++;

@@ -712,7 +713,7 @@ void machine_check_exception(struct pt_regs *regs)
panic("Unrecoverable Machine check");

exit:
- exception_exit(regs);
+ exception_exit(prev_state);
}

void SMIException(struct pt_regs *regs)
@@ -722,19 +723,21 @@ void SMIException(struct pt_regs *regs)

void unknown_exception(struct pt_regs *regs)
{
- exception_enter(regs);
+ enum ctx_state prev_state;
+ prev_state = exception_enter();

printk("Bad trap at PC: %lx, SR: %lx, vector=%lx\n",
regs->nip, regs->msr, regs->trap);

_exception(SIGTRAP, regs, 0, 0);

- exception_exit(regs);
+ exception_exit(prev_state);
}

void instruction_breakpoint_exception(struct pt_regs *regs)
{
- exception_enter(regs);
+ enum ctx_state prev_state;
+ prev_state = exception_enter();

if (notify_die(DIE_IABR_MATCH, "iabr_match", regs, 5,
5, SIGTRAP) == NOTIFY_STOP)
@@ -744,7 +747,7 @@ void instruction_breakpoint_exception(struct pt_regs *regs)
_exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip);

exit:
- exception_exit(regs);
+ exception_exit(prev_state);
}

void RunModeException(struct pt_regs *regs)
@@ -754,7 +757,8 @@ void RunModeException(struct pt_regs *regs)

void __kprobes single_step_exception(struct pt_regs *regs)
{
- exception_enter(regs);
+ enum ctx_state prev_state;
+ prev_state = exception_enter();

clear_single_step(regs);

@@ -767,7 +771,7 @@ void __kprobes single_step_exception(struct pt_regs *regs)
_exception(SIGTRAP, regs, TRAP_TRACE, regs->nip);

exit:
- exception_exit(regs);
+ exception_exit(prev_state);
}

/*
@@ -1020,9 +1024,10 @@ int is_valid_bugaddr(unsigned long addr)
void __kprobes program_check_exception(struct pt_regs *regs)
{
unsigned int reason = get_reason(regs);
+ enum ctx_state prev_state;
extern int do_mathemu(struct pt_regs *regs);

- exception_enter(regs);
+ prev_state = exception_enter();

/* We can now get here via a FP Unavailable exception if the core
* has no FPU, in that case the reason flags will be 0 */
@@ -1132,14 +1137,15 @@ void __kprobes program_check_exception(struct pt_regs *regs)
_exception(SIGILL, regs, ILL_ILLOPC, regs->nip);

exit:
- exception_exit(regs);
+ exception_exit(prev_state);
}

void alignment_exception(struct pt_regs *regs)
{
int sig, code, fixed = 0;
+ enum ctx_state prev_state;

- exception_enter(regs);
+ prev_state = exception_enter();

/* We restore the interrupt state now */
if (!arch_irq_disabled_regs(regs))
@@ -1169,7 +1175,7 @@ void alignment_exception(struct pt_regs *regs)
bad_page_fault(regs, regs->dar, sig);

exit:
- exception_exit(regs);
+ exception_exit(prev_state);
}

void StackOverflow(struct pt_regs *regs)
@@ -1198,18 +1204,20 @@ void trace_syscall(struct pt_regs *regs)

void kernel_fp_unavailable_exception(struct pt_regs *regs)
{
- exception_enter(regs);
+ enum ctx_state prev_state;
+ prev_state = exception_enter();

printk(KERN_EMERG "Unrecoverable FP Unavailable Exception "
"%lx at %lx\n", regs->trap, regs->nip);
die("Unrecoverable FP Unavailable Exception", regs, SIGABRT);

- exception_exit(regs);
+ exception_exit(prev_state);
}

void altivec_unavailable_exception(struct pt_regs *regs)
{
- exception_enter(regs);
+ enum ctx_state prev_state;
+ prev_state = exception_enter();

if (user_mode(regs)) {
/* A user program has executed an altivec instruction,
@@ -1223,7 +1231,7 @@ void altivec_unavailable_exception(struct pt_regs *regs)
die("Unrecoverable VMX/Altivec Unavailable Exception", regs, SIGABRT);

exit:
- exception_exit(regs);
+ exception_exit(prev_state);
}

void vsx_unavailable_exception(struct pt_regs *regs)
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 108ab17..141835b 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>
@@ -42,7 +43,6 @@
#include <asm/tlbflush.h>
#include <asm/siginfo.h>
#include <asm/debug.h>
-#include <asm/context_tracking.h>
#include <mm/mmu_decl.h>

#include "icswx.h"
@@ -480,9 +480,10 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
unsigned long error_code)
{
int ret;
- exception_enter(regs);
+ enum ctx_state prev_state;
+ prev_state = exception_enter();
ret = __do_page_fault(regs, address, error_code);
- exception_exit(regs);
+ exception_exit(prev_state);
return ret;
}

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 360fba8..eeab30f 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>
@@ -56,7 +57,6 @@
#include <asm/fadump.h>
#include <asm/firmware.h>
#include <asm/tm.h>
-#include <asm/context_tracking.h>

#ifdef DEBUG
#define DBG(fmt...) udbg_printf(fmt)
@@ -919,13 +919,17 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
const struct cpumask *tmp;
int rc, user_region = 0, local = 0;
int psize, ssize;
+ enum ctx_state prev_state;
+
+ prev_state = exception_enter();

DBG_LOW("hash_page(ea=%016lx, access=%lx, trap=%lx\n",
ea, access, trap);

if ((ea & ~REGION_MASK) >= PGTABLE_RANGE) {
DBG_LOW(" out of pgtable range !\n");
- return 1;
+ rc = 1;
+ goto exit;
}

/* Get region & vsid */
@@ -935,7 +939,8 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
mm = current->mm;
if (! mm) {
DBG_LOW(" user region with no mm !\n");
- return 1;
+ rc = 1;
+ goto exit;
}
psize = get_slice_psize(mm, ea);
ssize = user_segment_size(ea);
@@ -954,14 +959,17 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
/* Not a valid range
* Send the problem up to do_page_fault
*/
- return 1;
+ rc = 1;
+ goto exit;
}
DBG_LOW(" mm=%p, mm->pgdir=%p, vsid=%016lx\n", mm, mm->pgd, vsid);

/* Get pgdir */
pgdir = mm->pgd;
- if (pgdir == NULL)
- return 1;
+ if (pgdir == NULL) {
+ rc = 1;
+ goto exit;
+ }

/* Check CPU locality */
tmp = cpumask_of(smp_processor_id());
@@ -984,7 +992,8 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
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 exit;
}

/* Add _PAGE_PRESENT to the required access perm */
@@ -995,13 +1004,16 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
*/
if (access & ~pte_val(*ptep)) {
DBG_LOW(" no access !\n");
- return 1;
+ rc = 1;
+ goto exit;
}

#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 exit;
+ }
#endif /* CONFIG_HUGETLB_PAGE */

#ifndef CONFIG_PPC_64K_PAGES
@@ -1081,22 +1093,12 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
pte_val(*(ptep + PTRS_PER_PTE)));
#endif
DBG_LOW(" -> rc=%d\n", rc);
+exit:
+ exception_exit(prev_state);
return rc;
}
EXPORT_SYMBOL_GPL(hash_page);

-int hash_page_ct(unsigned long ea, unsigned long access,
- unsigned long trap, struct pt_regs *regs)
-{
- int ret;
-
- exception_enter(regs);
- ret = hash_page(ea, access, trap);
- exception_exit(regs);
-
- return ret;
-}
-
void hash_preload(struct mm_struct *mm, unsigned long ea,
unsigned long access, unsigned long trap)
{
@@ -1223,7 +1225,8 @@ void flush_hash_range(unsigned long number, int local)
*/
void low_hash_fault(struct pt_regs *regs, unsigned long address, int rc)
{
- exception_enter(regs);
+ enum ctx_state prev_state;
+ prev_state = exception_enter();

if (user_mode(regs)) {
#ifdef CONFIG_PPC_SUBPAGE_PROT
@@ -1235,7 +1238,7 @@ void low_hash_fault(struct pt_regs *regs, unsigned long address, int rc)
} else
bad_page_fault(regs, address, SIGBUS);

- exception_exit(regs);
+ exception_exit(prev_state);
}

#ifdef CONFIG_DEBUG_PAGEALLOC
--
1.7.9.5

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