Le 06/05/2020 à 05:40, Jordan Niethe a écrit :
If a prefixed instruction results in an alignment exception, the
SRR1_PREFIXED bit is set. The handler attempts to emulate the
responsible instruction and then increment the NIP past it. Use
SRR1_PREFIXED to determine by how much the NIP should be incremented.
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().
Shouldn't this patch go before patch 23 ?
Christophe
Reviewed-by: Alistair Popple <alist...@popple.id.au>
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: Rolled into "Add prefixed instructions to instruction data type"
v5: Only one definition of inst_length()
---
arch/powerpc/kernel/traps.c | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 493a3fa0ac1a..105242cc2f28 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -583,6 +583,8 @@ 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
/* single-step stuff */
#define single_stepping(regs) (current->thread.debug.dbcr0 & DBCR0_IC)
@@ -597,12 +599,16 @@ 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 single_stepping(regs) ((regs)->msr & MSR_SE)
#define clear_single_step(regs) ((regs)->msr &= ~MSR_SE)
#define clear_br_trace(regs) ((regs)->msr &= ~MSR_BE)
#endif
+#define inst_length(reason) (((reason) & REASON_PREFIXED) ? 8 : 4)
+
#if defined(CONFIG_E500)
int machine_check_e500mc(struct pt_regs *regs)
{
@@ -1593,11 +1599,20 @@ 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 +1621,8 @@ 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 +1635,7 @@ void alignment_exception(struct pt_regs *regs)
sig = SIGBUS;
code = BUS_ADRALN;
}
+bad:
if (user_mode(regs))
_exception(sig, regs, code, regs->dar);
else
