[v5,2/5] target/arm: handle M-profile semihosting at translate time
diff mbox series

Message ID 20190911164959.11003-3-alex.bennee@linaro.org
State New
Headers show
Series
  • semihosting cleanups (plus minor tests/tcg tweak)
Related show

Commit Message

Alex Bennée Sept. 11, 2019, 4:49 p.m. UTC
We do this for other semihosting calls so we might as well do it for
M-profile as well.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

---
v2
  - update for change to gen_exception_internal_insn API
v3
  - update for decode tree
v4
  - use !IS_USER
---
 target/arm/m_helper.c  | 18 ++++++------------
 target/arm/translate.c |  8 +++++++-
 2 files changed, 13 insertions(+), 13 deletions(-)

Comments

Peter Maydell Sept. 13, 2019, 1:03 p.m. UTC | #1
On Wed, 11 Sep 2019 at 17:50, Alex Bennée <alex.bennee@linaro.org> wrote:
>
> We do this for other semihosting calls so we might as well do it for
> M-profile as well.
>
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
>
> ---
> v2
>   - update for change to gen_exception_internal_insn API
> v3
>   - update for decode tree
> v4
>   - use !IS_USER
> ---

> diff --git a/target/arm/translate.c b/target/arm/translate.c
> index 34bb280e3da..6689acc911e 100644
> --- a/target/arm/translate.c
> +++ b/target/arm/translate.c
> @@ -8424,7 +8424,13 @@ static bool trans_BKPT(DisasContext *s, arg_BKPT *a)
>      if (!ENABLE_ARCH_5) {
>          return false;
>      }
> -    gen_exception_bkpt_insn(s, syn_aa32_bkpt(a->imm, false));
> +    if (arm_dc_feature(s, ARM_FEATURE_M) &&
> +        semihosting_enabled() && !IS_USER(s) &&
> +        (a->imm == 0xab)) {
> +        gen_exception_internal_insn(s, s->base.pc_next, EXCP_SEMIHOST);
> +    } else {
> +        gen_exception_bkpt_insn(s, syn_aa32_bkpt(a->imm, false));
> +    }
>      return true;
>  }

This is still disabling semihosting for the linux-user-mode
build for M-profile, isn't it ?

thanks
-- PMM
Alex Bennée Sept. 13, 2019, 1:28 p.m. UTC | #2
Peter Maydell <peter.maydell@linaro.org> writes:

> On Wed, 11 Sep 2019 at 17:50, Alex Bennée <alex.bennee@linaro.org> wrote:
>>
>> We do this for other semihosting calls so we might as well do it for
>> M-profile as well.
>>
>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
>>
>> ---
>> v2
>>   - update for change to gen_exception_internal_insn API
>> v3
>>   - update for decode tree
>> v4
>>   - use !IS_USER
>> ---
>
>> diff --git a/target/arm/translate.c b/target/arm/translate.c
>> index 34bb280e3da..6689acc911e 100644
>> --- a/target/arm/translate.c
>> +++ b/target/arm/translate.c
>> @@ -8424,7 +8424,13 @@ static bool trans_BKPT(DisasContext *s, arg_BKPT *a)
>>      if (!ENABLE_ARCH_5) {
>>          return false;
>>      }
>> -    gen_exception_bkpt_insn(s, syn_aa32_bkpt(a->imm, false));
>> +    if (arm_dc_feature(s, ARM_FEATURE_M) &&
>> +        semihosting_enabled() && !IS_USER(s) &&
>> +        (a->imm == 0xab)) {
>> +        gen_exception_internal_insn(s, s->base.pc_next, EXCP_SEMIHOST);
>> +    } else {
>> +        gen_exception_bkpt_insn(s, syn_aa32_bkpt(a->imm, false));
>> +    }
>>      return true;
>>  }
>
> This is still disabling semihosting for the linux-user-mode
> build for M-profile, isn't it ?

Sure - as rth suggested. But m-profile doesn't run Linux so why would we
support it in linux-user?

>
> thanks
> -- PMM


--
Alex Bennée
Peter Maydell Sept. 13, 2019, 1:31 p.m. UTC | #3
On Fri, 13 Sep 2019 at 14:28, Alex Bennée <alex.bennee@linaro.org> wrote:
>
>
> Peter Maydell <peter.maydell@linaro.org> writes:
> > This is still disabling semihosting for the linux-user-mode
> > build for M-profile, isn't it ?
>
> Sure - as rth suggested. But m-profile doesn't run Linux so why would we
> support it in linux-user?

(a) Linux does support Cortex-M, since it has no-mmu uCLinux style
support these days
(b) gcc test case binaries, which tend to get run on linux-user
even though in theory they're not actually Linux binaries

thanks
-- PMM
Peter Maydell Sept. 13, 2019, 1:48 p.m. UTC | #4
On Fri, 13 Sep 2019 at 14:31, Peter Maydell <peter.maydell@linaro.org> wrote:
>
> On Fri, 13 Sep 2019 at 14:28, Alex Bennée <alex.bennee@linaro.org> wrote:
> >
> >
> > Peter Maydell <peter.maydell@linaro.org> writes:
> > > This is still disabling semihosting for the linux-user-mode
> > > build for M-profile, isn't it ?
> >
> > Sure - as rth suggested. But m-profile doesn't run Linux so why would we
> > support it in linux-user?
>
> (a) Linux does support Cortex-M, since it has no-mmu uCLinux style
> support these days
> (b) gcc test case binaries, which tend to get run on linux-user
> even though in theory they're not actually Linux binaries

also I think (c) general principle -- don't change behaviour in what
looks like it's just a refactoring patchset.

thanks
-- PMM
Alex Bennée Sept. 13, 2019, 1:48 p.m. UTC | #5
Peter Maydell <peter.maydell@linaro.org> writes:

> On Fri, 13 Sep 2019 at 14:28, Alex Bennée <alex.bennee@linaro.org> wrote:
>>
>>
>> Peter Maydell <peter.maydell@linaro.org> writes:
>> > This is still disabling semihosting for the linux-user-mode
>> > build for M-profile, isn't it ?
>>
>> Sure - as rth suggested. But m-profile doesn't run Linux so why would we
>> support it in linux-user?
>
> (a) Linux does support Cortex-M, since it has no-mmu uCLinux style
> support these days

TIL

> (b) gcc test case binaries, which tend to get run on linux-user
> even though in theory they're not actually Linux binaries

Ahh ok - that's fair. I'll add the ifndef for that then.

>
> thanks
> -- PMM


--
Alex Bennée

Patch
diff mbox series

diff --git a/target/arm/m_helper.c b/target/arm/m_helper.c
index 884d35d2b02..27cd2f3f964 100644
--- a/target/arm/m_helper.c
+++ b/target/arm/m_helper.c
@@ -2114,19 +2114,13 @@  void arm_v7m_cpu_do_interrupt(CPUState *cs)
             break;
         }
         break;
+    case EXCP_SEMIHOST:
+        qemu_log_mask(CPU_LOG_INT,
+                      "...handling as semihosting call 0x%x\n",
+                      env->regs[0]);
+        env->regs[0] = do_arm_semihosting(env);
+        return;
     case EXCP_BKPT:
-        if (semihosting_enabled()) {
-            int nr;
-            nr = arm_lduw_code(env, env->regs[15], arm_sctlr_b(env)) & 0xff;
-            if (nr == 0xab) {
-                env->regs[15] += 2;
-                qemu_log_mask(CPU_LOG_INT,
-                              "...handling as semihosting call 0x%x\n",
-                              env->regs[0]);
-                env->regs[0] = do_arm_semihosting(env);
-                return;
-            }
-        }
         armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_DEBUG, false);
         break;
     case EXCP_IRQ:
diff --git a/target/arm/translate.c b/target/arm/translate.c
index 34bb280e3da..6689acc911e 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -8424,7 +8424,13 @@  static bool trans_BKPT(DisasContext *s, arg_BKPT *a)
     if (!ENABLE_ARCH_5) {
         return false;
     }
-    gen_exception_bkpt_insn(s, syn_aa32_bkpt(a->imm, false));
+    if (arm_dc_feature(s, ARM_FEATURE_M) &&
+        semihosting_enabled() && !IS_USER(s) &&
+        (a->imm == 0xab)) {
+        gen_exception_internal_insn(s, s->base.pc_next, EXCP_SEMIHOST);
+    } else {
+        gen_exception_bkpt_insn(s, syn_aa32_bkpt(a->imm, false));
+    }
     return true;
 }