[Qemu-devel] [PATCH] linux-user: SPARC "rd %tick" can be used by user application

[Qemu-devel] [PATCH] linux-user: SPARC "rd %tick" can be used by user application

[Laurent Vivier]

we have the same problem decribed in 7d6b1daedd
("linux-user, ppc: mftbl can be used by user application")
for ppc in the case of sparc.

When we use an application trying to resolve a name, it hangs in

    0x00000000ff5dd40c:  rd  %tick, %o5
    0x00000000ff5dd410:  srlx  %o5, 0x20, %o4
    0x00000000ff5dd414:  btst  %o5, %g4
    0x00000000ff5dd418:  be  %icc, 0xff5dd40c

because %tick is staying at 0.

As QEMU_CLOCK_VIRTUAL is not available in linux-user mode,
simply use cpu_get_host_ticks() instead.

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 target/sparc/helper.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/target/sparc/helper.c b/target/sparc/helper.c
index 1d854890b4..46232788c8 100644
--- a/target/sparc/helper.c
+++ b/target/sparc/helper.c
@@ -67,7 +67,9 @@ uint64_t helper_tick_get_count(CPUSPARCState *env, void *opaque, int mem_idx)
 
     return cpu_tick_get_count(timer);
 #else
-    return 0;
+    /* In user-mode, QEMU_CLOCK_VIRTUAL doesn't exist.
+       Just pass through the host cpu clock ticks.  */
+    return cpu_get_host_ticks();
 #endif
 }
 
-- 
2.14.3

Re: [Qemu-devel] [PATCH] linux-user: SPARC "rd %tick" can be used by user application

[Philippe Mathieu-Daudé]

On 05/28/2018 04:48 PM, Laurent Vivier wrote:
> we have the same problem decribed in 7d6b1daedd
> ("linux-user, ppc: mftbl can be used by user application")
> for ppc in the case of sparc.
> 
> When we use an application trying to resolve a name, it hangs in
> 
>     0x00000000ff5dd40c:  rd  %tick, %o5
>     0x00000000ff5dd410:  srlx  %o5, 0x20, %o4
>     0x00000000ff5dd414:  btst  %o5, %g4
>     0x00000000ff5dd418:  be  %icc, 0xff5dd40c
> 
> because %tick is staying at 0.
> 
> As QEMU_CLOCK_VIRTUAL is not available in linux-user mode,
> simply use cpu_get_host_ticks() instead.
> 
> Signed-off-by: Laurent Vivier <laurent@vivier.eu>

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

> ---
>  target/sparc/helper.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/target/sparc/helper.c b/target/sparc/helper.c
> index 1d854890b4..46232788c8 100644
> --- a/target/sparc/helper.c
> +++ b/target/sparc/helper.c
> @@ -67,7 +67,9 @@ uint64_t helper_tick_get_count(CPUSPARCState *env, void *opaque, int mem_idx)
>  
>      return cpu_tick_get_count(timer);
>  #else
> -    return 0;
> +    /* In user-mode, QEMU_CLOCK_VIRTUAL doesn't exist.
> +       Just pass through the host cpu clock ticks.  */
> +    return cpu_get_host_ticks();
>  #endif
>  }
>  
>