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Re: [Qemu-devel] [PATCH v3 14/16] tcg/arm: Return false on failure from
From: |
Alex Bennée |
Subject: |
Re: [Qemu-devel] [PATCH v3 14/16] tcg/arm: Return false on failure from patch_reloc |
Date: |
Mon, 03 Dec 2018 10:43:44 +0000 |
User-agent: |
mu4e 1.1.0; emacs 26.1.90 |
Richard Henderson <address@hidden> writes:
> This does require an extra two checks within the slow paths
> to replace the assert that we're moving.
>
> Signed-off-by: Richard Henderson <address@hidden>
Reviewed-by: Alex Bennée <address@hidden>
> ---
> tcg/arm/tcg-target.inc.c | 22 ++++++++++++++++------
> 1 file changed, 16 insertions(+), 6 deletions(-)
>
> diff --git a/tcg/arm/tcg-target.inc.c b/tcg/arm/tcg-target.inc.c
> index deefa20fbf..49f57d655e 100644
> --- a/tcg/arm/tcg-target.inc.c
> +++ b/tcg/arm/tcg-target.inc.c
> @@ -187,10 +187,14 @@ static const uint8_t tcg_cond_to_arm_cond[] = {
> [TCG_COND_GTU] = COND_HI,
> };
>
> -static inline void reloc_pc24(tcg_insn_unit *code_ptr, tcg_insn_unit *target)
> +static inline bool reloc_pc24(tcg_insn_unit *code_ptr, tcg_insn_unit *target)
> {
> ptrdiff_t offset = (tcg_ptr_byte_diff(target, code_ptr) - 8) >> 2;
> - *code_ptr = (*code_ptr & ~0xffffff) | (offset & 0xffffff);
> + if (offset == sextract32(offset, 0, 24)) {
> + *code_ptr = (*code_ptr & ~0xffffff) | (offset & 0xffffff);
> + return true;
> + }
> + return false;
> }
>
> static bool patch_reloc(tcg_insn_unit *code_ptr, int type,
> @@ -199,7 +203,7 @@ static bool patch_reloc(tcg_insn_unit *code_ptr, int type,
> tcg_debug_assert(addend == 0);
>
> if (type == R_ARM_PC24) {
> - reloc_pc24(code_ptr, (tcg_insn_unit *)value);
> + return reloc_pc24(code_ptr, (tcg_insn_unit *)value);
> } else if (type == R_ARM_PC13) {
> intptr_t diff = value - (uintptr_t)(code_ptr + 2);
> tcg_insn_unit insn = *code_ptr;
> @@ -213,7 +217,11 @@ static bool patch_reloc(tcg_insn_unit *code_ptr, int
> type,
> } else {
> int rd = extract32(insn, 12, 4);
> int rt = rd == TCG_REG_PC ? TCG_REG_TMP : rd;
> - assert(diff >= 0x1000 && diff < 0x100000);
> +
> + if (diff < 0x1000 || diff >= 0x100000) {
> + return false;
> + }
> +
> /* add rt, pc, #high */
> *code_ptr++ = ((insn & 0xf0000000) | (1 << 25) | ARITH_ADD
> | (TCG_REG_PC << 16) | (rt << 12)
> @@ -1372,7 +1380,8 @@ static void tcg_out_qemu_ld_slow_path(TCGContext *s,
> TCGLabelQemuLdst *lb)
> TCGMemOp opc = get_memop(oi);
> void *func;
>
> - reloc_pc24(lb->label_ptr[0], s->code_ptr);
> + bool ok = reloc_pc24(lb->label_ptr[0], s->code_ptr);
> + tcg_debug_assert(ok);
>
> argreg = tcg_out_arg_reg32(s, TCG_REG_R0, TCG_AREG0);
> if (TARGET_LONG_BITS == 64) {
> @@ -1432,7 +1441,8 @@ static void tcg_out_qemu_st_slow_path(TCGContext *s,
> TCGLabelQemuLdst *lb)
> TCGMemOpIdx oi = lb->oi;
> TCGMemOp opc = get_memop(oi);
>
> - reloc_pc24(lb->label_ptr[0], s->code_ptr);
> + bool ok = reloc_pc24(lb->label_ptr[0], s->code_ptr);
> + tcg_debug_assert(ok);
>
> argreg = TCG_REG_R0;
> argreg = tcg_out_arg_reg32(s, argreg, TCG_AREG0);
--
Alex Bennée
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