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Re: [Qemu-stable] [PATCH] tcg/aarch64: Fix tcg_out_qemu_{ld, st} for gue
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-stable] [PATCH] tcg/aarch64: Fix tcg_out_qemu_{ld, st} for guest_base == 0 |
Date: |
Wed, 2 Sep 2015 11:01:53 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 |
On 01/09/2015 22:07, Richard Henderson wrote:
> In ffc6372851d8631a9f9fa56ec613b3244dc635b9, we swapped the guest
> base to the address base register from the address index register.
> Except that 31 in the base slot is SP not XZR, so we need to be
> more intelligent about which reg gets placed in which slot.
>
> Cc: Paolo Bonzini <address@hidden>
> Cc: Aurelien Jarno <address@hidden>
> Cc: Richard Henderson <address@hidden>
> Cc: address@hidden (v2.4.0)
> Reported-by: Andreas Färber <address@hidden>
> Signed-off-by: Richard Henderson <address@hidden>
> ---
> tcg/aarch64/tcg-target.c | 27 ++++++++++++++++++++-------
> 1 file changed, 20 insertions(+), 7 deletions(-)
>
> diff --git a/tcg/aarch64/tcg-target.c b/tcg/aarch64/tcg-target.c
> index 01ae610..0ed10a9 100644
> --- a/tcg/aarch64/tcg-target.c
> +++ b/tcg/aarch64/tcg-target.c
> @@ -56,6 +56,11 @@ static const int tcg_target_call_oarg_regs[1] = {
> #define TCG_REG_TMP TCG_REG_X30
>
> #ifndef CONFIG_SOFTMMU
> +/* Note that XZR cannot be encoded in the address base register slot,
> + as that actaully encodes SP. So if we need to zero-extend the guest
> + address, via the address index register slot, we need to load even
> + a zero guest base into a register. */
> +#define USE_GUEST_BASE (guest_base != 0 || TARGET_LONG_BITS == 32)
> #define TCG_REG_GUEST_BASE TCG_REG_X28
> #endif
>
> @@ -1224,9 +1229,13 @@ static void tcg_out_qemu_ld(TCGContext *s, TCGReg
> data_reg, TCGReg addr_reg,
> add_qemu_ldst_label(s, true, oi, ext, data_reg, addr_reg,
> s->code_ptr, label_ptr);
> #else /* !CONFIG_SOFTMMU */
> - tcg_out_qemu_ld_direct(s, memop, ext, data_reg,
> - guest_base ? TCG_REG_GUEST_BASE : TCG_REG_XZR,
> - otype, addr_reg);
> + if (USE_GUEST_BASE) {
> + tcg_out_qemu_ld_direct(s, memop, ext, data_reg,
> + TCG_REG_GUEST_BASE, otype, addr_reg);
> + } else {
> + tcg_out_qemu_ld_direct(s, memop, ext, data_reg,
> + addr_reg, TCG_TYPE_I64, TCG_REG_XZR);
> + }
> #endif /* CONFIG_SOFTMMU */
> }
>
> @@ -1245,9 +1254,13 @@ static void tcg_out_qemu_st(TCGContext *s, TCGReg
> data_reg, TCGReg addr_reg,
> add_qemu_ldst_label(s, false, oi, (memop & MO_SIZE)== MO_64,
> data_reg, addr_reg, s->code_ptr, label_ptr);
> #else /* !CONFIG_SOFTMMU */
> - tcg_out_qemu_st_direct(s, memop, data_reg,
> - guest_base ? TCG_REG_GUEST_BASE : TCG_REG_XZR,
> - otype, addr_reg);
> + if (USE_GUEST_BASE) {
> + tcg_out_qemu_st_direct(s, memop, data_reg,
> + TCG_REG_GUEST_BASE, otype, addr_reg);
> + } else {
> + tcg_out_qemu_st_direct(s, memop, data_reg,
> + addr_reg, TCG_TYPE_I64, TCG_REG_XZR);
> + }
> #endif /* CONFIG_SOFTMMU */
> }
>
> @@ -1806,7 +1819,7 @@ static void tcg_target_qemu_prologue(TCGContext *s)
> CPU_TEMP_BUF_NLONGS * sizeof(long));
>
> #if !defined(CONFIG_SOFTMMU)
> - if (guest_base) {
> + if (USE_GUEST_BASE) {
> tcg_out_movi(s, TCG_TYPE_PTR, TCG_REG_GUEST_BASE, guest_base);
> tcg_regset_set_reg(s->reserved_regs, TCG_REG_GUEST_BASE);
> }
>
Reviewed-by: Paolo Bonzini <address@hidden>