| Message ID | 20240207081820.28559-1-jason.chien@sifive.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] target/riscv: Update $ra with current $pc in trans_cm_jalt() | expand |
On 2/6/24 22:18, Jason Chien wrote: > The original implementation sets $pc to the address read from the jump > vector table first and links $ra with the address of the next instruction > after the updated $pc. After jumping to the updated $pc and executing the > next ret instruction, the program jumps to $ra, which is in the same > function currently executing, which results in an infinite loop. > This commit stores the jump address in a temporary, updates $ra with the > current $pc, and copies the temporary to $pc. > > Signed-off-by: Jason Chien <jason.chien@sifive.com> > Reviewed-by: Frank Chang <frank.chang@sifive.com> > --- > target/riscv/insn_trans/trans_rvzce.c.inc | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~ > > diff --git a/target/riscv/insn_trans/trans_rvzce.c.inc b/target/riscv/insn_trans/trans_rvzce.c.inc > index 2d992e14c4..cd234ad960 100644 > --- a/target/riscv/insn_trans/trans_rvzce.c.inc > +++ b/target/riscv/insn_trans/trans_rvzce.c.inc > @@ -293,12 +293,14 @@ static bool trans_cm_jalt(DisasContext *ctx, arg_cm_jalt *a) > { > REQUIRE_ZCMT(ctx); > > + TCGv addr = tcg_temp_new(); > + > /* > * Update pc to current for the non-unwinding exception > * that might come from cpu_ld*_code() in the helper. > */ > gen_update_pc(ctx, 0); > - gen_helper_cm_jalt(cpu_pc, tcg_env, tcg_constant_i32(a->index)); > + gen_helper_cm_jalt(addr, tcg_env, tcg_constant_i32(a->index)); > > /* c.jt vs c.jalt depends on the index. */ > if (a->index >= 32) { > @@ -307,6 +309,8 @@ static bool trans_cm_jalt(DisasContext *ctx, arg_cm_jalt *a) > gen_set_gpr(ctx, xRA, succ_pc); > } > > + tcg_gen_mov_tl(cpu_pc, addr); > + > tcg_gen_lookup_and_goto_ptr(); > ctx->base.is_jmp = DISAS_NORETURN; > return true;
On Wed, Feb 7, 2024 at 6:18 PM Jason Chien <jason.chien@sifive.com> wrote: > > The original implementation sets $pc to the address read from the jump > vector table first and links $ra with the address of the next instruction > after the updated $pc. After jumping to the updated $pc and executing the > next ret instruction, the program jumps to $ra, which is in the same > function currently executing, which results in an infinite loop. > This commit stores the jump address in a temporary, updates $ra with the > current $pc, and copies the temporary to $pc. > > Signed-off-by: Jason Chien <jason.chien@sifive.com> > Reviewed-by: Frank Chang <frank.chang@sifive.com> Thanks! Applied to riscv-to-apply.next Alistair > --- > target/riscv/insn_trans/trans_rvzce.c.inc | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/target/riscv/insn_trans/trans_rvzce.c.inc b/target/riscv/insn_trans/trans_rvzce.c.inc > index 2d992e14c4..cd234ad960 100644 > --- a/target/riscv/insn_trans/trans_rvzce.c.inc > +++ b/target/riscv/insn_trans/trans_rvzce.c.inc > @@ -293,12 +293,14 @@ static bool trans_cm_jalt(DisasContext *ctx, arg_cm_jalt *a) > { > REQUIRE_ZCMT(ctx); > > + TCGv addr = tcg_temp_new(); > + > /* > * Update pc to current for the non-unwinding exception > * that might come from cpu_ld*_code() in the helper. > */ > gen_update_pc(ctx, 0); > - gen_helper_cm_jalt(cpu_pc, tcg_env, tcg_constant_i32(a->index)); > + gen_helper_cm_jalt(addr, tcg_env, tcg_constant_i32(a->index)); > > /* c.jt vs c.jalt depends on the index. */ > if (a->index >= 32) { > @@ -307,6 +309,8 @@ static bool trans_cm_jalt(DisasContext *ctx, arg_cm_jalt *a) > gen_set_gpr(ctx, xRA, succ_pc); > } > > + tcg_gen_mov_tl(cpu_pc, addr); > + > tcg_gen_lookup_and_goto_ptr(); > ctx->base.is_jmp = DISAS_NORETURN; > return true; > -- > 2.43.0 > >
diff --git a/target/riscv/insn_trans/trans_rvzce.c.inc b/target/riscv/insn_trans/trans_rvzce.c.inc index 2d992e14c4..cd234ad960 100644 --- a/target/riscv/insn_trans/trans_rvzce.c.inc +++ b/target/riscv/insn_trans/trans_rvzce.c.inc @@ -293,12 +293,14 @@ static bool trans_cm_jalt(DisasContext *ctx, arg_cm_jalt *a) { REQUIRE_ZCMT(ctx); + TCGv addr = tcg_temp_new(); + /* * Update pc to current for the non-unwinding exception * that might come from cpu_ld*_code() in the helper. */ gen_update_pc(ctx, 0); - gen_helper_cm_jalt(cpu_pc, tcg_env, tcg_constant_i32(a->index)); + gen_helper_cm_jalt(addr, tcg_env, tcg_constant_i32(a->index)); /* c.jt vs c.jalt depends on the index. */ if (a->index >= 32) { @@ -307,6 +309,8 @@ static bool trans_cm_jalt(DisasContext *ctx, arg_cm_jalt *a) gen_set_gpr(ctx, xRA, succ_pc); } + tcg_gen_mov_tl(cpu_pc, addr); + tcg_gen_lookup_and_goto_ptr(); ctx->base.is_jmp = DISAS_NORETURN; return true;