[PATCH 1/4] ARM: context tracking: add exception support

[Kevin Hilman]

Add ARM support for the context tracking subsystem by instrumenting
exception entry/exit points.

Special thanks to Mats Liljegren for testing, collaboration and adding
support for exceptions/faults that were missing in early test versions.

Cc: Mats Liljegren <mats.liljegren at enea.com>
Signed-off-by: Kevin Hilman <khilman at linaro.org>
---
 arch/arm/kernel/traps.c | 18 +++++++++++++++++-
 arch/arm/mm/fault.c     | 32 +++++++++++++++++++++++++++-----
 2 files changed, 44 insertions(+), 6 deletions(-)

diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 1c08911..0e5f9fa 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -25,6 +25,7 @@
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/sched.h>
+#include <linux/context_tracking.h>
 
 #include <linux/atomic.h>
 #include <asm/cacheflush.h>
@@ -405,7 +406,9 @@ asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
 	unsigned int instr;
 	siginfo_t info;
 	void __user *pc;
+	enum ctx_state prev_state;
 
+	prev_state = exception_enter();
 	pc = (void __user *)instruction_pointer(regs);
 
 	if (processor_mode(regs) == SVC_MODE) {
@@ -433,8 +436,10 @@ asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
 		goto die_sig;
 	}
 
-	if (call_undef_hook(regs, instr) == 0)
+	if (call_undef_hook(regs, instr) == 0) {
+		exception_exit(prev_state);
 		return;
+	}
 
 die_sig:
 #ifdef CONFIG_DEBUG_USER
@@ -451,12 +456,17 @@ die_sig:
 	info.si_addr  = pc;
 
 	arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
+	exception_exit(prev_state);
 }
 
 asmlinkage void do_unexp_fiq (struct pt_regs *regs)
 {
+	enum ctx_state prev_state;
+
+	prev_state = exception_enter();
 	printk("Hmm.  Unexpected FIQ received, but trying to continue\n");
 	printk("You may have a hardware problem...\n");
+	exception_exit(prev_state);
 }
 
 /*
@@ -467,6 +477,9 @@ asmlinkage void do_unexp_fiq (struct pt_regs *regs)
  */
 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
 {
+	enum ctx_state prev_state;
+
+	prev_state = exception_enter();
 	console_verbose();
 
 	printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
@@ -746,7 +759,9 @@ baddataabort(int code, unsigned long instr, struct pt_regs *regs)
 {
 	unsigned long addr = instruction_pointer(regs);
 	siginfo_t info;
+	enum ctx_state prev_state;
 
+	prev_state = exception_enter();
 #ifdef CONFIG_DEBUG_USER
 	if (user_debug & UDBG_BADABORT) {
 		printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
@@ -762,6 +777,7 @@ baddataabort(int code, unsigned long instr, struct pt_regs *regs)
 	info.si_addr  = (void __user *)addr;
 
 	arm_notify_die("unknown data abort code", regs, &info, instr, 0);
+	exception_exit(prev_state);
 }
 
 void __readwrite_bug(const char *fn)
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 5dbf13f..759b70d 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -19,6 +19,7 @@
 #include <linux/sched.h>
 #include <linux/highmem.h>
 #include <linux/perf_event.h>
+#include <linux/context_tracking.h>
 
 #include <asm/exception.h>
 #include <asm/pgtable.h>
@@ -424,9 +425,15 @@ do_translation_fault(unsigned long addr, unsigned int fsr,
 	pgd_t *pgd, *pgd_k;
 	pud_t *pud, *pud_k;
 	pmd_t *pmd, *pmd_k;
-
-	if (addr < TASK_SIZE)
-		return do_page_fault(addr, fsr, regs);
+	enum ctx_state prev_state;
+
+	prev_state = exception_enter();
+	if (addr < TASK_SIZE) {
+		int ret;
+		ret = do_page_fault(addr, fsr, regs);
+		exception_exit(prev_state);
+		return ret;
+	}
 
 	if (user_mode(regs))
 		goto bad_area;
@@ -472,10 +479,12 @@ do_translation_fault(unsigned long addr, unsigned int fsr,
 		goto bad_area;
 
 	copy_pmd(pmd, pmd_k);
+	exception_exit(prev_state);
 	return 0;
 
 bad_area:
 	do_bad_area(addr, fsr, regs);
+	exception_exit(prev_state);
 	return 0;
 }
 #else					/* CONFIG_MMU */
@@ -494,7 +503,12 @@ do_translation_fault(unsigned long addr, unsigned int fsr,
 static int
 do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 {
+	enum ctx_state prev_state;
+
+	prev_state = exception_enter();
 	do_bad_area(addr, fsr, regs);
+	exception_exit(prev_state);
+
 	return 0;
 }
 
@@ -542,9 +556,11 @@ do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 {
 	const struct fsr_info *inf = fsr_info + fsr_fs(fsr);
 	struct siginfo info;
+	enum ctx_state prev_state;
 
+	prev_state = exception_enter();
 	if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
-		return;
+		goto out;
 
 	printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
 		inf->name, fsr, addr);
@@ -554,6 +570,8 @@ do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	info.si_code  = inf->code;
 	info.si_addr  = (void __user *)addr;
 	arm_notify_die("", regs, &info, fsr, 0);
+out:
+	exception_exit(prev_state);
 }
 
 void __init
@@ -574,9 +592,11 @@ do_PrefetchAbort(unsigned long addr, unsigned int ifsr, struct pt_regs *regs)
 {
 	const struct fsr_info *inf = ifsr_info + fsr_fs(ifsr);
 	struct siginfo info;
+	enum ctx_state prev_state;
 
+	prev_state = exception_enter();
 	if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
-		return;
+		goto out;
 
 	printk(KERN_ALERT "Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
 		inf->name, ifsr, addr);
@@ -586,6 +606,8 @@ do_PrefetchAbort(unsigned long addr, unsigned int ifsr, struct pt_regs *regs)
 	info.si_code  = inf->code;
 	info.si_addr  = (void __user *)addr;
 	arm_notify_die("", regs, &info, ifsr, 0);
+out:
+	exception_exit(prev_state);
 }
 
 #ifndef CONFIG_ARM_LPAE
-- 
1.8.2