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SubjectRe: [PATCH 1/5] msm: Secure Channel Manager (SCM) support
On Wed, Dec 15, 2010 at 08:48:11AM +0100, Pavel Machek wrote:

> > +static u32 smc(dma_addr_t cmd_addr)
> > +{
> > + int context_id;
> > + register u32 r0 asm("r0") = 1;
> > + register u32 r1 asm("r1") = (u32)&context_id;
> > + register u32 r2 asm("r2") = (u32)cmd_addr;
>
> Are these neccessary?

The values have to be in specific registers. Without them it doesn't
generate the right code.

> > + asm(
> > + __asmeq("%0", "r0")
> > + __asmeq("%1", "r0")
> > + __asmeq("%2", "r1")
> > + __asmeq("%3", "r2")
> > + "smc #0 @ switch to secure world\n"
> > + : "=r" (r0)
> > + : "r" (r0), "r" (r1), "r" (r2)
> > + : "r3");
> > + return r0;
> > +}
>
> > +u32 scm_get_version(void)
> > +{
> > + int context_id;
> > + static u32 version = -1;
> > + register u32 r0 asm("r0") = 0x1 << 8;
> > + register u32 r1 asm("r1") = (u32)&context_id;
>
> And does this even work?

In what sense? It generates the desired code.

> > + if (version != -1)
> > + return version;
> > +
> > + mutex_lock(&scm_lock);
> > + asm(
> > + __asmeq("%0", "r1")
> > + __asmeq("%1", "r0")
> > + __asmeq("%2", "r1")
> > + "smc #0 @ switch to secure world\n"
> > + : "=r" (r1)
> > + : "r" (r0), "r" (r1)
> > + : "r2", "r3");
> > + version = r1;
> > + mutex_unlock(&scm_lock);
> > +
> > + return version;
> > +}

--
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.


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