On Tue, Mar 10, 2015 at 12:18 PM, Peter Maydell
<peter.mayd...@linaro.org> wrote:
> The A32 encoding of LDM distinguishes LDM (user) from LDM (exception
> return) based on whether r15 is in the register list. However for
> STM (user) there is no equivalent distinction. We were incorrectly
> treating "r15 in list" as indicating exception return for both LDM
> and STM, with the result that an STM (user) involving r15 went into
> an infinite loop. Fix this; note that the value stored for r15
> in this case is the current PC regardless of our current mode.
>
> Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
> ---
> target-arm/translate.c | 18 ++++++++++++------
> 1 file changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/target-arm/translate.c b/target-arm/translate.c
> index 36868ed..ed8fcea 100644
> --- a/target-arm/translate.c
> +++ b/target-arm/translate.c
> @@ -8859,17 +8859,23 @@ static void disas_arm_insn(DisasContext *s, unsigned
> int insn)
> case 0x08:
> case 0x09:
> {
> - int j, n, user, loaded_base;
> + int j, n, loaded_base;
> + bool exc_return = false;
> + bool is_load = extract32(insn, 20, 1);
> + bool user = false;
> TCGv_i32 loaded_var;
> /* load/store multiple words */
> /* XXX: store correct base if write back */
> - user = 0;
> if (insn & (1 << 22)) {
> + /* LDM (user), LDM (exception return) and STM (user) */
> if (IS_USER(s))
> goto illegal_op; /* only usable in supervisor mode */
>
> - if ((insn & (1 << 15)) == 0)
> - user = 1;
> + if (is_load && extract32(insn, 15, 1)) {
> + exc_return = true;
> + } else {
> + user = true;
> + }
> }
> rn = (insn >> 16) & 0xf;
> addr = load_reg(s, rn);
> @@ -8903,7 +8909,7 @@ static void disas_arm_insn(DisasContext *s, unsigned
> int insn)
> j = 0;
> for(i=0;i<16;i++) {
> if (insn & (1 << i)) {
> - if (insn & (1 << 20)) {
> + if (is_load) {
> /* load */
> tmp = tcg_temp_new_i32();
> gen_aa32_ld32u(tmp, addr, get_mem_index(s));
> @@ -8968,7 +8974,7 @@ static void disas_arm_insn(DisasContext *s, unsigned
> int insn)
> if (loaded_base) {
> store_reg(s, rn, loaded_var);
> }
> - if ((insn & (1 << 22)) && !user) {
> + if (exc_return) {
> /* Restore CPSR from SPSR. */
> tmp = load_cpu_field(spsr);
> gen_set_cpsr(tmp, CPSR_ERET_MASK);
> --
> 1.9.1
>
>
Reviewed-by: Greg Bellows <greg.bell...@linaro.org>
