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[Qemu-ppc] [PULL 2/3] ppc: Fix the bad exception NIP value and the range
From: |
David Gibson |
Subject: |
[Qemu-ppc] [PULL 2/3] ppc: Fix the bad exception NIP value and the range check in LSWX |
Date: |
Mon, 18 Apr 2016 15:17:46 +1000 |
From: Thomas Huth <address@hidden>
The range checks in the LSWX instruction are completely insufficient:
They do not take the wrap-around case into account, and the check
"reg < rx" should be "reg <= rx" instead. Fix it by using the new
lsw_reg_in_range() helper function that is already used for LSWI, too.
Then there is a second problem: In case the INVAL exception is generated,
the NIP value is wrong, it currently points to the instruction before
the LSWX instruction. This is because gen_lswx() already decreases the
NIP value by 4 (to be prepared for page fault exceptions), and
powerpc_excp() later decreases it again by 4 while handling the program
exception. So to get this right, we've got to undo the "- 4" from
gen_lswx() here before calling helper_raise_exception_err().
Signed-off-by: Thomas Huth <address@hidden>
Signed-off-by: David Gibson <address@hidden>
---
target-ppc/mem_helper.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/target-ppc/mem_helper.c b/target-ppc/mem_helper.c
index 581d9fa..6d584c9 100644
--- a/target-ppc/mem_helper.c
+++ b/target-ppc/mem_helper.c
@@ -102,8 +102,9 @@ void helper_lswx(CPUPPCState *env, target_ulong addr,
uint32_t reg,
{
if (likely(xer_bc != 0)) {
int num_used_regs = (xer_bc + 3) / 4;
- if (unlikely((ra != 0 && reg < ra && (reg + num_used_regs) > ra) ||
- (reg < rb && (reg + num_used_regs) > rb))) {
+ if (unlikely((ra != 0 && lsw_reg_in_range(reg, num_used_regs, ra)) ||
+ lsw_reg_in_range(reg, num_used_regs, rb))) {
+ env->nip += 4; /* Compensate the "nip - 4" from gen_lswx() */
helper_raise_exception_err(env, POWERPC_EXCP_PROGRAM,
POWERPC_EXCP_INVAL |
POWERPC_EXCP_INVAL_LSWX);
--
2.5.5