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Date: Sun, 7 Oct 2018 22:51:53 +0200
From: Helge Deller <deller@gmx.de>
Message-ID: <20181007205153.GA30270@ls3530.fritz.box>
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Subject: [Qemu-devel] [PATCH] qemu-system-hppa: Raise exception 26 on
 emulated hardware
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To: qemu-devel@nongnu.org
Cc: Richard Henderson <rth@twiddle.net>

On PCXS chips (PA7000, pa 1.1a), trap #18 is raised on memory faults,
while all later chips (>= PA7100) generate either trap #26, #27 or #28
(depending on the fault type).

Since the current qemu emulation emulates a B160L machine (with a
PA7300LC PCX-L2 chip, we should raise trap #26 (EXCP_DMAR) instead of
#18 (EXCP_DMP) on access faults by the Linux kernel to page zero.

With the patch we now get the correct output (I tested against real
hardware):
 Kernel Fault: Code=26 (Data memory access rights trap) (Addr=00000004)
instead of:
 Kernel Fault: Code=18 (Data memory protection/unaligned access trap) (Addr=00000004)

Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/target/hppa/mem_helper.c b/target/hppa/mem_helper.c
index ab160c2a74..aecf3075f6 100644
--- a/target/hppa/mem_helper.c
+++ b/target/hppa/mem_helper.c
@@ -137,7 +137,8 @@ int hppa_get_physical_address(CPUHPPAState *env, vaddr addr, int mmu_idx,
 
     if (unlikely(!(prot & type))) {
         /* The access isn't allowed -- Inst/Data Memory Protection Fault.  */
-        ret = (type & PAGE_EXEC ? EXCP_IMP : EXCP_DMP);
+        ret = (type & PAGE_EXEC ? EXCP_IMP :
+               prot & PAGE_READ ? EXCP_DMP : EXCP_DMAR);
         goto egress;
     }