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authorEmilio G. Cota <cota@braap.org>2018-04-10 11:09:52 -0400
committerRichard Henderson <richard.henderson@linaro.org>2018-05-09 10:12:21 -0700
commitbfe7ad5be77a6a8925a7ab1628452c8942222102 (patch)
treec7d530eeee4dee001046971a67e0a032ad7a4343
parent56371527f3f8d33be651046700d72489f4df505f (diff)
target/arm: avoid integer overflow in next_page PC check
If the PC is in the last page of the address space, next_page_start overflows to 0. Fix it. Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Cc: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Emilio G. Cota <cota@braap.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
-rw-r--r--target/arm/translate.c11
-rw-r--r--target/arm/translate.h2
2 files changed, 6 insertions, 7 deletions
diff --git a/target/arm/translate.c b/target/arm/translate.c
index ad208867a7..0f6629f745 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -9930,7 +9930,7 @@ static bool thumb_insn_is_16bit(DisasContext *s, uint32_t insn)
return false;
}
- if ((insn >> 11) == 0x1e && (s->pc < s->next_page_start - 3)) {
+ if ((insn >> 11) == 0x1e && s->pc - s->page_start < TARGET_PAGE_SIZE - 3) {
/* 0b1111_0xxx_xxxx_xxxx : BL/BLX prefix, and the suffix
* is not on the next page; we merge this into a 32-bit
* insn.
@@ -12301,8 +12301,7 @@ static int arm_tr_init_disas_context(DisasContextBase *dcbase,
dc->is_ldex = false;
dc->ss_same_el = false; /* Can't be true since EL_d must be AArch64 */
- dc->next_page_start =
- (dc->base.pc_first & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE;
+ dc->page_start = dc->base.pc_first & TARGET_PAGE_MASK;
/* If architectural single step active, limit to 1. */
if (is_singlestepping(dc)) {
@@ -12312,7 +12311,7 @@ static int arm_tr_init_disas_context(DisasContextBase *dcbase,
/* ARM is a fixed-length ISA. Bound the number of insns to execute
to those left on the page. */
if (!dc->thumb) {
- int bound = (dc->next_page_start - dc->base.pc_first) / 4;
+ int bound = -(dc->base.pc_first | TARGET_PAGE_MASK) / 4;
max_insns = MIN(max_insns, bound);
}
@@ -12584,8 +12583,8 @@ static void thumb_tr_translate_insn(DisasContextBase *dcbase, CPUState *cpu)
* but isn't very efficient).
*/
if (dc->base.is_jmp == DISAS_NEXT
- && (dc->pc >= dc->next_page_start
- || (dc->pc >= dc->next_page_start - 3
+ && (dc->pc - dc->page_start >= TARGET_PAGE_SIZE
+ || (dc->pc - dc->page_start >= TARGET_PAGE_SIZE - 3
&& insn_crosses_page(env, dc)))) {
dc->base.is_jmp = DISAS_TOO_MANY;
}
diff --git a/target/arm/translate.h b/target/arm/translate.h
index 4428c98e2e..37a1bba056 100644
--- a/target/arm/translate.h
+++ b/target/arm/translate.h
@@ -9,7 +9,7 @@ typedef struct DisasContext {
DisasContextBase base;
target_ulong pc;
- target_ulong next_page_start;
+ target_ulong page_start;
uint32_t insn;
/* Nonzero if this instruction has been conditionally skipped. */
int condjmp;