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Re: [PATCH] tcg/riscv: Fix base register for user-only qemu_ld/st
From: |
Alistair Francis |
Subject: |
Re: [PATCH] tcg/riscv: Fix base register for user-only qemu_ld/st |
Date: |
Wed, 26 Oct 2022 09:34:37 +1000 |
On Mon, Oct 24, 2022 at 1:26 PM Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> When guest_base != 0, we were not coordinating the usage of
> TCG_REG_TMP0 as base properly, leading to a previous zero-extend
> of the input address being discarded.
>
> Shuffle the alignment check to the front, because that does not
> depend on the zero-extend, and it keeps the register usage clear.
> Set base after each step of the address arithmetic instead of before.
>
> Return the base register used from tcg_out_tlb_load, so as to
> keep that register choice localized to that function.
>
> Reported-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Thanks!
Applied to riscv-to-apply.next
Alistair
> ---
> tcg/riscv/tcg-target.c.inc | 39 +++++++++++++++++++++-----------------
> 1 file changed, 22 insertions(+), 17 deletions(-)
>
> diff --git a/tcg/riscv/tcg-target.c.inc b/tcg/riscv/tcg-target.c.inc
> index 2a84c57bec..e3b608034f 100644
> --- a/tcg/riscv/tcg-target.c.inc
> +++ b/tcg/riscv/tcg-target.c.inc
> @@ -923,9 +923,9 @@ static void tcg_out_goto(TCGContext *s, const
> tcg_insn_unit *target)
> tcg_debug_assert(ok);
> }
>
> -static void tcg_out_tlb_load(TCGContext *s, TCGReg addrl,
> - TCGReg addrh, MemOpIdx oi,
> - tcg_insn_unit **label_ptr, bool is_load)
> +static TCGReg tcg_out_tlb_load(TCGContext *s, TCGReg addrl,
> + TCGReg addrh, MemOpIdx oi,
> + tcg_insn_unit **label_ptr, bool is_load)
> {
> MemOp opc = get_memop(oi);
> unsigned s_bits = opc & MO_SIZE;
> @@ -975,6 +975,7 @@ static void tcg_out_tlb_load(TCGContext *s, TCGReg addrl,
> addrl = TCG_REG_TMP0;
> }
> tcg_out_opc_reg(s, OPC_ADD, TCG_REG_TMP0, TCG_REG_TMP2, addrl);
> + return TCG_REG_TMP0;
> }
>
> static void add_qemu_ldst_label(TCGContext *s, int is_ld, MemOpIdx oi,
> @@ -1177,7 +1178,7 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg
> *args, bool is_64)
> #else
> unsigned a_bits;
> #endif
> - TCGReg base = TCG_REG_TMP0;
> + TCGReg base;
>
> data_regl = *args++;
> data_regh = (TCG_TARGET_REG_BITS == 32 && is_64 ? *args++ : 0);
> @@ -1187,23 +1188,25 @@ static void tcg_out_qemu_ld(TCGContext *s, const
> TCGArg *args, bool is_64)
> opc = get_memop(oi);
>
> #if defined(CONFIG_SOFTMMU)
> - tcg_out_tlb_load(s, addr_regl, addr_regh, oi, label_ptr, 1);
> + base = tcg_out_tlb_load(s, addr_regl, addr_regh, oi, label_ptr, 1);
> tcg_out_qemu_ld_direct(s, data_regl, data_regh, base, opc, is_64);
> add_qemu_ldst_label(s, 1, oi,
> (is_64 ? TCG_TYPE_I64 : TCG_TYPE_I32),
> data_regl, data_regh, addr_regl, addr_regh,
> s->code_ptr, label_ptr);
> #else
> - if (TCG_TARGET_REG_BITS > TARGET_LONG_BITS) {
> - tcg_out_ext32u(s, base, addr_regl);
> - addr_regl = base;
> - }
> a_bits = get_alignment_bits(opc);
> if (a_bits) {
> tcg_out_test_alignment(s, true, addr_regl, a_bits);
> }
> + base = addr_regl;
> + if (TCG_TARGET_REG_BITS > TARGET_LONG_BITS) {
> + tcg_out_ext32u(s, TCG_REG_TMP0, base);
> + base = TCG_REG_TMP0;
> + }
> if (guest_base != 0) {
> - tcg_out_opc_reg(s, OPC_ADD, base, TCG_GUEST_BASE_REG, addr_regl);
> + tcg_out_opc_reg(s, OPC_ADD, TCG_REG_TMP0, TCG_GUEST_BASE_REG, base);
> + base = TCG_REG_TMP0;
> }
> tcg_out_qemu_ld_direct(s, data_regl, data_regh, base, opc, is_64);
> #endif
> @@ -1249,7 +1252,7 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg
> *args, bool is_64)
> #else
> unsigned a_bits;
> #endif
> - TCGReg base = TCG_REG_TMP0;
> + TCGReg base;
>
> data_regl = *args++;
> data_regh = (TCG_TARGET_REG_BITS == 32 && is_64 ? *args++ : 0);
> @@ -1259,23 +1262,25 @@ static void tcg_out_qemu_st(TCGContext *s, const
> TCGArg *args, bool is_64)
> opc = get_memop(oi);
>
> #if defined(CONFIG_SOFTMMU)
> - tcg_out_tlb_load(s, addr_regl, addr_regh, oi, label_ptr, 0);
> + base = tcg_out_tlb_load(s, addr_regl, addr_regh, oi, label_ptr, 0);
> tcg_out_qemu_st_direct(s, data_regl, data_regh, base, opc);
> add_qemu_ldst_label(s, 0, oi,
> (is_64 ? TCG_TYPE_I64 : TCG_TYPE_I32),
> data_regl, data_regh, addr_regl, addr_regh,
> s->code_ptr, label_ptr);
> #else
> - if (TCG_TARGET_REG_BITS > TARGET_LONG_BITS) {
> - tcg_out_ext32u(s, base, addr_regl);
> - addr_regl = base;
> - }
> a_bits = get_alignment_bits(opc);
> if (a_bits) {
> tcg_out_test_alignment(s, false, addr_regl, a_bits);
> }
> + base = addr_regl;
> + if (TCG_TARGET_REG_BITS > TARGET_LONG_BITS) {
> + tcg_out_ext32u(s, TCG_REG_TMP0, base);
> + base = TCG_REG_TMP0;
> + }
> if (guest_base != 0) {
> - tcg_out_opc_reg(s, OPC_ADD, base, TCG_GUEST_BASE_REG, addr_regl);
> + tcg_out_opc_reg(s, OPC_ADD, TCG_REG_TMP0, TCG_GUEST_BASE_REG, base);
> + base = TCG_REG_TMP0;
> }
> tcg_out_qemu_st_direct(s, data_regl, data_regh, base, opc);
> #endif
> --
> 2.34.1
>
>