| Message ID | 20181113235045.14155-5-palmer@sifive.com |
|---|---|
| State | New |
| Headers | show |
| Series | [PR,RFC] RISC-V Patches for 3.1-rc2 | expand |
Nits. Please improve your commit message to make them more impersonal... On Wed, Nov 14, 2018 at 12:52 PM Palmer Dabbelt <palmer@sifive.com> wrote: > Our current fence implementation ignores fences for the user-only > configurations. This is incorrect but unlikely to manifest: it requires > multi-threaded user-only code that takes advantage of the weakness in > the host's memory model and can be inlined by TCG. > The RISC-V fence implementation... > This patch simply treats fences the same way for all our emulators. > I've given it to testing as I don't want to construct a test that would > actually trigger the failure. > Testing has been limited to... ? Reproducer? > Our fence implementation has an additional deficiency where we map all > RISC-V fences to full fences. Now that we have a formal memory model > for RISC-V we can start to take advantage of the strength bits on our > fence instructions. This requires a bit more though, so I'm going to > split it out because the implementation is still correct without taking > advantage of these weaker fences. > The fence implementation... A formal memory model for RISC-V allows... > Thanks to Richard Henderson for pointing out both of the issues. > > Signed-off-by: Palmer Dabbelt <palmer@sifive.com> > Reviewed-by: Alistair Francis <alistair.francis@wdc.com> > Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Assuming you fix up the commit message. I am not sure if I am present in any of the commit messages I wrote, however perhaps thats just a matter style with respect to writing (or re-writing) history. Reviewed-by: Michael Clark <mjc@sifive.com> --- > target/riscv/translate.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/target/riscv/translate.c b/target/riscv/translate.c > index f44eb9c41b48..312bf298b3c2 100644 > --- a/target/riscv/translate.c > +++ b/target/riscv/translate.c > @@ -1776,7 +1776,6 @@ static void decode_RV32_64G(CPURISCVState *env, > DisasContext *ctx) > GET_RM(ctx->opcode)); > break; > case OPC_RISC_FENCE: > -#ifndef CONFIG_USER_ONLY > if (ctx->opcode & 0x1000) { > /* FENCE_I is a no-op in QEMU, > * however we need to end the translation block */ > @@ -1787,7 +1786,6 @@ static void decode_RV32_64G(CPURISCVState *env, > DisasContext *ctx) > /* FENCE is a full memory barrier. */ > tcg_gen_mb(TCG_MO_ALL | TCG_BAR_SC); > } > -#endif > break; > case OPC_RISC_SYSTEM: > gen_system(env, ctx, MASK_OP_SYSTEM(ctx->opcode), rd, rs1, > -- > 2.18.1 > > >
diff --git a/target/riscv/translate.c b/target/riscv/translate.c index f44eb9c41b48..312bf298b3c2 100644 --- a/target/riscv/translate.c +++ b/target/riscv/translate.c @@ -1776,7 +1776,6 @@ static void decode_RV32_64G(CPURISCVState *env, DisasContext *ctx) GET_RM(ctx->opcode)); break; case OPC_RISC_FENCE: -#ifndef CONFIG_USER_ONLY if (ctx->opcode & 0x1000) { /* FENCE_I is a no-op in QEMU, * however we need to end the translation block */ @@ -1787,7 +1786,6 @@ static void decode_RV32_64G(CPURISCVState *env, DisasContext *ctx) /* FENCE is a full memory barrier. */ tcg_gen_mb(TCG_MO_ALL | TCG_BAR_SC); } -#endif break; case OPC_RISC_SYSTEM: gen_system(env, ctx, MASK_OP_SYSTEM(ctx->opcode), rd, rs1,