From b637b865ed54d15de620b25f23d937845ebf91e5 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Tue, 7 Nov 2017 13:03:51 +0000 Subject: translate.c: Fix usermode big-endian AArch32 LDREXD and STREXD For AArch32 LDREXD and STREXD, architecturally the 32-bit word at the lowest address is always Rt and the one at addr+4 is Rt2, even if the CPU is big-endian. Our implementation does these with a single 64-bit store, so if we're big-endian then we need to put the two 32-bit halves together in the opposite order to little-endian, so that they end up in the right places. We were trying to do this with the gen_aa32_frob64() function, but that is not correct for the usermode emulator, because there there is a distinction between "load a 64 bit value" (which does a BE 64-bit access and doesn't need swapping) and "load two 32 bit values as one 64 bit access" (where we still need to do the swapping, like system mode BE32). Fixes: https://bugs.launchpad.net/qemu/+bug/1725267 Cc: qemu-stable@nongnu.org Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Message-id: 1509622400-13351-1-git-send-email-peter.maydell@linaro.org (cherry picked from commit 3448d47b3172015006b79197eb5a69826c6a7b6d) Signed-off-by: Michael Roth --- target/arm/translate.c | 39 ++++++++++++++++++++++++++++++++++----- 1 file changed, 34 insertions(+), 5 deletions(-) diff --git a/target/arm/translate.c b/target/arm/translate.c index d1a5f56998..ad758d333d 100644 --- a/target/arm/translate.c +++ b/target/arm/translate.c @@ -7858,9 +7858,27 @@ static void gen_load_exclusive(DisasContext *s, int rt, int rt2, TCGv_i32 tmp2 = tcg_temp_new_i32(); TCGv_i64 t64 = tcg_temp_new_i64(); - gen_aa32_ld_i64(s, t64, addr, get_mem_index(s), opc); + /* For AArch32, architecturally the 32-bit word at the lowest + * address is always Rt and the one at addr+4 is Rt2, even if + * the CPU is big-endian. That means we don't want to do a + * gen_aa32_ld_i64(), which invokes gen_aa32_frob64() as if + * for an architecturally 64-bit access, but instead do a + * 64-bit access using MO_BE if appropriate and then split + * the two halves. + * This only makes a difference for BE32 user-mode, where + * frob64() must not flip the two halves of the 64-bit data + * but this code must treat BE32 user-mode like BE32 system. + */ + TCGv taddr = gen_aa32_addr(s, addr, opc); + + tcg_gen_qemu_ld_i64(t64, taddr, get_mem_index(s), opc); + tcg_temp_free(taddr); tcg_gen_mov_i64(cpu_exclusive_val, t64); - tcg_gen_extr_i64_i32(tmp, tmp2, t64); + if (s->be_data == MO_BE) { + tcg_gen_extr_i64_i32(tmp2, tmp, t64); + } else { + tcg_gen_extr_i64_i32(tmp, tmp2, t64); + } tcg_temp_free_i64(t64); store_reg(s, rt2, tmp2); @@ -7909,15 +7927,26 @@ static void gen_store_exclusive(DisasContext *s, int rd, int rt, int rt2, TCGv_i64 n64 = tcg_temp_new_i64(); t2 = load_reg(s, rt2); - tcg_gen_concat_i32_i64(n64, t1, t2); + /* For AArch32, architecturally the 32-bit word at the lowest + * address is always Rt and the one at addr+4 is Rt2, even if + * the CPU is big-endian. Since we're going to treat this as a + * single 64-bit BE store, we need to put the two halves in the + * opposite order for BE to LE, so that they end up in the right + * places. + * We don't want gen_aa32_frob64() because that does the wrong + * thing for BE32 usermode. + */ + if (s->be_data == MO_BE) { + tcg_gen_concat_i32_i64(n64, t2, t1); + } else { + tcg_gen_concat_i32_i64(n64, t1, t2); + } tcg_temp_free_i32(t2); - gen_aa32_frob64(s, n64); tcg_gen_atomic_cmpxchg_i64(o64, taddr, cpu_exclusive_val, n64, get_mem_index(s), opc); tcg_temp_free_i64(n64); - gen_aa32_frob64(s, o64); tcg_gen_setcond_i64(TCG_COND_NE, o64, o64, cpu_exclusive_val); tcg_gen_extrl_i64_i32(t0, o64); -- cgit v1.2.1