From 9409d2f9dad2f0679d67dc24d8116dd3e837b035 Mon Sep 17 00:00:00 2001
From: Jordan Niethe <jniethe5@gmail.com>
Date: Wed, 6 May 2020 13:40:48 +1000
Subject: [PATCH] powerpc: Support prefixed instructions in alignment handler
References: jsc#SLE-13847
Patch-mainline: v5.8-rc1
Git-commit: 9409d2f9dad2f0679d67dc24d8116dd3e837b035
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().
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Alistair Popple <alistair@popple.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-29-jniethe5@gmail.com
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
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 e37bf7945d27..051d7028e71f 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -588,6 +588,8 @@ 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)
@@ -602,12 +604,16 @@ 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)
{
@@ -1610,11 +1616,20 @@ 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;
@@ -1623,7 +1638,8 @@ 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;
}
@@ -1636,6 +1652,7 @@ void alignment_exception(struct pt_regs *regs)
sig = SIGBUS;
code = BUS_ADRALN;
}
+bad:
if (user_mode(regs))
_exception(sig, regs, code, regs->dar);
else
--
2.26.2