Alignment interrupts can be caused by prefixed instructions accessing
memory. Prefixed instructions are not permitted to cross 64-byte
boundaries. If they do the alignment interrupt is invoked with SRR1
BOUNDARY bit set. If this occurs send a SIGBUS to the offending process
if in user mode. If in kernel mode call bad_page_fault().
Signed-off-by: Jordan Niethe <jniet...@gmail.com>
---
v2: - Move __get_user_instr() and __get_user_instr_inatomic() to this
commit (previously in "powerpc sstep: Prepare to support prefixed
instructions").
- Rename sufx to suffix
- Use a macro for calculating instruction length
v3: Move __get_user_{instr(), instr_inatomic()} up with the other
get_user definitions and remove nested if.
v4: Just do the things for alignment_exception(). Other changes handled
elsewhere.
---
arch/powerpc/kernel/traps.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index a4764b039749..cd8b3043c268 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -583,6 +583,10 @@ static inline int check_io_access(struct pt_regs *regs)
#define REASON_ILLEGAL (ESR_PIL | ESR_PUO)
#define REASON_PRIVILEGED ESR_PPR
#define REASON_TRAP ESR_PTR
+#define REASON_PREFIXED 0
+#define REASON_BOUNDARY 0
+
+#define inst_length(reason) 4
/* single-step stuff */
#define single_stepping(regs) (current->thread.debug.dbcr0 & DBCR0_IC)
@@ -597,6 +601,10 @@ static inline int check_io_access(struct pt_regs *regs)
#define REASON_ILLEGAL SRR1_PROGILL
#define REASON_PRIVILEGED SRR1_PROGPRIV
#define REASON_TRAP SRR1_PROGTRAP
+#define REASON_PREFIXED SRR1_PREFIXED
+#define REASON_BOUNDARY SRR1_BOUNDARY
+
+#define inst_length(reason) (((reason) & REASON_PREFIXED) ? 8 : 4)
#define single_stepping(regs) ((regs)->msr & MSR_SE)
#define clear_single_step(regs) ((regs)->msr &= ~MSR_SE)
@@ -1593,11 +1601,20 @@ void alignment_exception(struct pt_regs *regs)
{
enum ctx_state prev_state = exception_enter();
int sig, code, fixed = 0;
+ unsigned long reason;
/* We restore the interrupt state now */
if (!arch_irq_disabled_regs(regs))
local_irq_enable();
+ reason = get_reason(regs);
+
+ if (reason & REASON_BOUNDARY) {
+ sig = SIGBUS;
+ code = BUS_ADRALN;
+ goto bad;
+ }
+
if (tm_abort_check(regs, TM_CAUSE_ALIGNMENT | TM_CAUSE_PERSISTENT))
goto bail;
@@ -1606,7 +1623,8 @@ void alignment_exception(struct pt_regs *regs)
fixed = fix_alignment(regs);
if (fixed == 1) {
- regs->nip += 4; /* skip over emulated instruction */
+ /* skip over emulated instruction */
+ regs->nip += inst_length(reason);
emulate_single_step(regs);
goto bail;
}
@@ -1619,6 +1637,7 @@ void alignment_exception(struct pt_regs *regs)
sig = SIGBUS;
code = BUS_ADRALN;
}
+bad:
if (user_mode(regs))
_exception(sig, regs, code, regs->dar);
else
--
2.17.1
