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ppc: Fix the range check in the LSWI instruction 

There are two issues: First, the number of registers that are used has
to be calculated with "(nb + 3) / 4" (i.e. round always up, not down).
Second, the "start <= ra && (start + nr - 32) > ra" condition for the
wrap-around case is wrong: It has to be tested with "||" instead of "&&".
Since we can reuse this check later for the LSWX instruction, let's
place the fixed code into a helper function, too.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Thomas Huth 2016-04-14 17:14:52 +02:00 committed by David Gibson
parent c7b45f1282
commit afbee7128c
2 changed files with 12 additions and 4 deletions
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10
target-ppc/cpu.h
View File

@ -2415,6 +2415,16 @@ static inline bool msr_is_64bit(CPUPPCState *env, target_ulong msr)
return msr & (1ULL << MSR_SF); return msr & (1ULL << MSR_SF);
} }
/**
* Check whether register rx is in the range between start and
* start + nregs (as needed by the LSWX and LSWI instructions)
*/
static inline bool lsw_reg_in_range(int start, int nregs, int rx)
{
return (start + nregs <= 32 && rx >= start && rx < start + nregs) ||
(start + nregs > 32 && (rx >= start || rx < start + nregs - 32));
}
extern void (*cpu_ppc_hypercall)(PowerPCCPU *); extern void (*cpu_ppc_hypercall)(PowerPCCPU *);
#include "exec/exec-all.h" #include "exec/exec-all.h"

6
target-ppc/translate.c
View File

@ -3227,10 +3227,8 @@ static void gen_lswi(DisasContext *ctx)
if (nb == 0) if (nb == 0)
nb = 32; nb = 32;
nr = nb / 4; nr = (nb + 3) / 4;
if (unlikely(((start + nr) > 32 && if (unlikely(lsw_reg_in_range(start, nr, ra))) {
start <= ra && (start + nr - 32) > ra) ||
((start + nr) <= 32 && start <= ra && (start + nr) > ra))) {
gen_inval_exception(ctx, POWERPC_EXCP_INVAL_LSWX); gen_inval_exception(ctx, POWERPC_EXCP_INVAL_LSWX);
return; return;
} }