From fe5e88fabf5fdef582b0e5b4edff339e163a51f8 Mon Sep 17 00:00:00 2001
From: Justin Hibbits <jhibbits@FreeBSD.org>
Date: Mon, 19 Nov 2018 23:54:49 +0000
Subject: [PATCH] powerpc: Sync icache on SIGILL, in case of cache issues

The update of jemalloc to 5.1.0 exposed a cache syncing issue on a Freescale
e500 base system.  There was already code in the FPU emulator to address
this, but it was limited to a single static variable, and did not attempt to
sync the cache.  This pulls that out to the higher level program exception
handler, and syncs the cache.

If a SIGILL is hit a second time at the same address, it will be treated as
a real illegal instruction, and handled accordingly.
---
 sys/powerpc/fpu/fpu_emu.c          | 13 +++----------
 sys/powerpc/include/pcb.h          |  1 +
 sys/powerpc/powerpc/exec_machdep.c | 10 ++++++++++
 3 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/sys/powerpc/fpu/fpu_emu.c b/sys/powerpc/fpu/fpu_emu.c
index 75f44c7b786a..4d7231e5da93 100644
--- a/sys/powerpc/fpu/fpu_emu.c
+++ b/sys/powerpc/fpu/fpu_emu.c
@@ -189,7 +189,6 @@ fpu_emulate(struct trapframe *frame, struct fpu *fpf)
 {
 	union instr insn;
 	struct fpemu fe;
-	static int lastill = 0;
 	int sig;
 
 	/* initialize insn.is_datasize to tell it is *not* initialized */
@@ -243,17 +242,11 @@ fpu_emulate(struct trapframe *frame, struct fpu *fpf)
 			opc_disasm(frame->srr0, insn.i_int);
 		}
 #endif
-		/*
-		* XXXX retry an illegal insn once due to cache issues.
-		*/
-		if (lastill == frame->srr0) {
-			sig = SIGILL;
+		sig = SIGILL;
 #ifdef DEBUG
-			if (fpe_debug & FPE_EX)
-				kdb_enter(KDB_WHY_UNSET, "illegal instruction");
+		if (fpe_debug & FPE_EX)
+			kdb_enter(KDB_WHY_UNSET, "illegal instruction");
 #endif
-		}
-		lastill = frame->srr0;
 		break;
 	}
 
diff --git a/sys/powerpc/include/pcb.h b/sys/powerpc/include/pcb.h
index 451b730225ca..df0e2ff6951b 100644
--- a/sys/powerpc/include/pcb.h
+++ b/sys/powerpc/include/pcb.h
@@ -89,6 +89,7 @@ struct pcb {
 			register_t	dbcr0;
 		} booke;
 	} pcb_cpu;
+	vm_offset_t pcb_lastill;	/* Last illegal instruction */
 };
 #endif
 
diff --git a/sys/powerpc/powerpc/exec_machdep.c b/sys/powerpc/powerpc/exec_machdep.c
index 18ff66f26f3f..718962ffcb6f 100644
--- a/sys/powerpc/powerpc/exec_machdep.c
+++ b/sys/powerpc/powerpc/exec_machdep.c
@@ -94,6 +94,8 @@ __FBSDID("$FreeBSD$");
 #include <machine/trap.h>
 #include <machine/vmparam.h>
 
+#include <vm/pmap.h>
+
 #ifdef FPU_EMU
 #include <powerpc/fpu/fpu_extern.h>
 #endif
@@ -1099,6 +1101,14 @@ ppc_instr_emulate(struct trapframe *frame, struct pcb *pcb)
 	}
 	sig = fpu_emulate(frame, &pcb->pcb_fpu);
 #endif
+	if (sig == SIGILL) {
+		if (pcb->pcb_lastill != frame->srr0) {
+			/* Allow a second chance, in case of cache sync issues. */
+			sig = 0;
+			pmap_sync_icache(PCPU_GET(curpmap), frame->srr0, 4);
+			pcb->pcb_lastill = frame->srr0;
+		}
+	}
 
 	return (sig);
 }