On Wed, May 12, 2021 at 05:14:24PM +0100, Alexandru Elisei wrote:
> Hi Drew,
>
> On 4/29/21 5:41 PM, Andrew Jones wrote:
> > The method can be smc in addition to hvc, and it will be when running
> > on bare metal. Additionally, we move the invocations to assembly so
> > we don't have to rely on compiler assumptions. We also fix the
> > prototype of psci_invoke. It should return long, not int, and
> > function_id should be an unsigned int, not an unsigned long.
>
> Sorry to harp on this again, but to be honest, it's still not clear to me why the
> psci_invoke_{hvc,smc} functions return a long int.
>
> If we only expect the PSCI functions to return error codes, then the PSCI spec
> says these are 32-bit signed integers. If we want to support PSCI functions
> returning other values, like PSCI_STAT_{RESIDENCY,COUNT}, then the invoke
> functions should return an unsigned value.
>
> The only case we're supporting is the error return for the SMC calling convention
> (which says that error codes are 32/64bit signed integers).
psci_invoke_{hvc,smc} should implement the SMC calling convention, since
they're just wrapping the smc/hvc call. PSCI calls that build on that,
e.g. psci_cpu_on, can define their own return type and then translate
the signed long returned by SMC into, e.g. 32-bit signed integers. Indeed
that's what psci_cpu_on does.
I would write something like that in the commit message or rename
psci_invoke to smc_invoke.
Thanks,
drew
> Since the commit
> specifically mentions this change, I think some explanation why this width was
> chosen would be appropriate. Unless it's painfully obvious and I'm just not seeing
> it, which is a possibility.
>
> Other than that, the patch looks good. I'll some tests to make sure everything is
> in order.
>
> Thanks,
>
> Alex
>
> >
> > Signed-off-by: Andrew Jones <drjones@xxxxxxxxxx>
> > ---
> > arm/cstart.S | 22 ++++++++++++++++++++++
> > arm/cstart64.S | 22 ++++++++++++++++++++++
> > arm/selftest.c | 34 +++++++---------------------------
> > lib/arm/asm/psci.h | 10 ++++++++--
> > lib/arm/psci.c | 35 +++++++++++++++++++++++++++--------
> > lib/arm/setup.c | 2 ++
> > 6 files changed, 88 insertions(+), 37 deletions(-)
> >
> > diff --git a/arm/cstart.S b/arm/cstart.S
> > index 446966de350d..2401d92cdadc 100644
> > --- a/arm/cstart.S
> > +++ b/arm/cstart.S
> > @@ -95,6 +95,28 @@ start:
> >
> > .text
> >
> > +/*
> > + * psci_invoke_hvc / psci_invoke_smc
> > + *
> > + * Inputs:
> > + * r0 -- function_id
> > + * r1 -- arg0
> > + * r2 -- arg1
> > + * r3 -- arg2
> > + *
> > + * Outputs:
> > + * r0 -- return code
> > + */
> > +.globl psci_invoke_hvc
> > +psci_invoke_hvc:
> > + hvc #0
> > + mov pc, lr
> > +
> > +.globl psci_invoke_smc
> > +psci_invoke_smc:
> > + smc #0
> > + mov pc, lr
> > +
> > enable_vfp:
> > /* Enable full access to CP10 and CP11: */
> > mov r0, #(3 << 22 | 3 << 20)
> > diff --git a/arm/cstart64.S b/arm/cstart64.S
> > index 42ba3a3ca249..e4ab7d06251e 100644
> > --- a/arm/cstart64.S
> > +++ b/arm/cstart64.S
> > @@ -109,6 +109,28 @@ start:
> >
> > .text
> >
> > +/*
> > + * psci_invoke_hvc / psci_invoke_smc
> > + *
> > + * Inputs:
> > + * w0 -- function_id
> > + * x1 -- arg0
> > + * x2 -- arg1
> > + * x3 -- arg2
> > + *
> > + * Outputs:
> > + * x0 -- return code
> > + */
> > +.globl psci_invoke_hvc
> > +psci_invoke_hvc:
> > + hvc #0
> > + ret
> > +
> > +.globl psci_invoke_smc
> > +psci_invoke_smc:
> > + smc #0
> > + ret
> > +
> > get_mmu_off:
> > adrp x0, auxinfo
> > ldr x0, [x0, :lo12:auxinfo + 8]
> > diff --git a/arm/selftest.c b/arm/selftest.c
> > index 4495b161cdd5..9f459ed3d571 100644
> > --- a/arm/selftest.c
> > +++ b/arm/selftest.c
> > @@ -400,33 +400,13 @@ static void check_vectors(void *arg __unused)
> > exit(report_summary());
> > }
> >
> > -static bool psci_check(void)
> > +static void psci_print(void)
> > {
> > - const struct fdt_property *method;
> > - int node, len, ver;
> > -
> > - node = fdt_node_offset_by_compatible(dt_fdt(), -1, "arm,psci-0.2");
> > - if (node < 0) {
> > - printf("PSCI v0.2 compatibility required\n");
> > - return false;
> > - }
> > -
> > - method = fdt_get_property(dt_fdt(), node, "method", &len);
> > - if (method == NULL) {
> > - printf("bad psci device tree node\n");
> > - return false;
> > - }
> > -
> > - if (len < 4 || strcmp(method->data, "hvc") != 0) {
> > - printf("psci method must be hvc\n");
> > - return false;
> > - }
> > -
> > - ver = psci_invoke(PSCI_0_2_FN_PSCI_VERSION, 0, 0, 0);
> > - printf("PSCI version %d.%d\n", PSCI_VERSION_MAJOR(ver),
> > - PSCI_VERSION_MINOR(ver));
> > -
> > - return true;
> > + int ver = psci_invoke(PSCI_0_2_FN_PSCI_VERSION, 0, 0, 0);
> > + report_info("PSCI version: %d.%d", PSCI_VERSION_MAJOR(ver),
> > + PSCI_VERSION_MINOR(ver));
> > + report_info("PSCI method: %s", psci_invoke == psci_invoke_hvc ?
> > + "hvc" : "smc");
> > }
> >
> > static void cpu_report(void *data __unused)
> > @@ -465,7 +445,7 @@ int main(int argc, char **argv)
> >
> > } else if (strcmp(argv[1], "smp") == 0) {
> >
> > - report(psci_check(), "PSCI version");
> > + psci_print();
> > on_cpus(cpu_report, NULL);
> > while (!cpumask_full(&ready))
> > cpu_relax();
> > diff --git a/lib/arm/asm/psci.h b/lib/arm/asm/psci.h
> > index 7b956bf5987d..f87fca0422cc 100644
> > --- a/lib/arm/asm/psci.h
> > +++ b/lib/arm/asm/psci.h
> > @@ -3,8 +3,14 @@
> > #include <libcflat.h>
> > #include <linux/psci.h>
> >
> > -extern int psci_invoke(unsigned long function_id, unsigned long arg0,
> > - unsigned long arg1, unsigned long arg2);
> > +typedef long (*psci_invoke_fn)(unsigned int function_id, unsigned long arg0,
> > + unsigned long arg1, unsigned long arg2);
> > +extern psci_invoke_fn psci_invoke;
> > +extern long psci_invoke_hvc(unsigned int function_id, unsigned long arg0,
> > + unsigned long arg1, unsigned long arg2);
> > +extern long psci_invoke_smc(unsigned int function_id, unsigned long arg0,
> > + unsigned long arg1, unsigned long arg2);
> > +extern void psci_set_conduit(void);
> > extern int psci_cpu_on(unsigned long cpuid, unsigned long entry_point);
> > extern void psci_system_reset(void);
> > extern int cpu_psci_cpu_boot(unsigned int cpu);
> > diff --git a/lib/arm/psci.c b/lib/arm/psci.c
> > index 936c83948b6a..3053b3041c28 100644
> > --- a/lib/arm/psci.c
> > +++ b/lib/arm/psci.c
> > @@ -6,22 +6,21 @@
> > *
> > * This work is licensed under the terms of the GNU LGPL, version 2.
> > */
> > +#include <devicetree.h>
> > #include <asm/psci.h>
> > #include <asm/setup.h>
> > #include <asm/page.h>
> > #include <asm/smp.h>
> >
> > -__attribute__((noinline))
> > -int psci_invoke(unsigned long function_id, unsigned long arg0,
> > - unsigned long arg1, unsigned long arg2)
> > +static long psci_invoke_none(unsigned int function_id, unsigned long arg0,
> > + unsigned long arg1, unsigned long arg2)
> > {
> > - asm volatile(
> > - "hvc #0"
> > - : "+r" (function_id)
> > - : "r" (arg0), "r" (arg1), "r" (arg2));
> > - return function_id;
> > + printf("No PSCI method configured! Can't invoke...\n");
> > + return PSCI_RET_NOT_PRESENT;
> > }
> >
> > +psci_invoke_fn psci_invoke = psci_invoke_none;
> > +
> > int psci_cpu_on(unsigned long cpuid, unsigned long entry_point)
> > {
> > #ifdef __arm__
> > @@ -56,3 +55,23 @@ void psci_system_off(void)
> > int err = psci_invoke(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
> > printf("CPU%d unable to do system off (error = %d)\n", smp_processor_id(), err);
> > }
> > +
> > +void psci_set_conduit(void)
> > +{
> > + const void *fdt = dt_fdt();
> > + const struct fdt_property *method;
> > + int node, len;
> > +
> > + node = fdt_node_offset_by_compatible(fdt, -1, "arm,psci-0.2");
> > + assert_msg(node >= 0, "PSCI v0.2 compatibility required");
> > +
> > + method = fdt_get_property(fdt, node, "method", &len);
> > + assert(method != NULL && len == 4);
> > +
> > + if (strcmp(method->data, "hvc") == 0)
> > + psci_invoke = psci_invoke_hvc;
> > + else if (strcmp(method->data, "smc") == 0)
> > + psci_invoke = psci_invoke_smc;
> > + else
> > + assert_msg(false, "Unknown PSCI conduit: %s", method->data);
> > +}
> > diff --git a/lib/arm/setup.c b/lib/arm/setup.c
> > index 86f054304baf..bcdf0d78c2e2 100644
> > --- a/lib/arm/setup.c
> > +++ b/lib/arm/setup.c
> > @@ -25,6 +25,7 @@
> > #include <asm/processor.h>
> > #include <asm/smp.h>
> > #include <asm/timer.h>
> > +#include <asm/psci.h>
> >
> > #include "io.h"
> >
> > @@ -266,6 +267,7 @@ void setup(const void *fdt, phys_addr_t freemem_start)
> > mem_regions_add_assumed();
> > mem_init(PAGE_ALIGN((unsigned long)freemem));
> >
> > + psci_set_conduit();
> > cpu_init();
> >
> > /* cpu_init must be called before thread_info_init */
>
