[PATCH 15/17] lib: utils/irqchip: Use scratch space to save per-HART PLIC pointer

[Anup Patel]

On Mon, Jun 5, 2023 at 11:13 AM Jessica Clarke <jrtc27 at jrtc27.com> wrote:
>
> On 25 Apr 2023, at 13:32, Anup Patel <apatel at ventanamicro.com> wrote:
> >
> > Instead of using a global array indexed by hartid, we should use
> > scratch space to save per-HART PLIC pointer and PLIC context numbers.
> >
> > Signed-off-by: Anup Patel <apatel at ventanamicro.com>
> > ---
> > lib/utils/irqchip/fdt_irqchip_plic.c | 108 +++++++++++++++++++++------
> > 1 file changed, 86 insertions(+), 22 deletions(-)
> >
> > diff --git a/lib/utils/irqchip/fdt_irqchip_plic.c b/lib/utils/irqchip/fdt_irqchip_plic.c
> > index 605f44a..eb1e412 100644
> > --- a/lib/utils/irqchip/fdt_irqchip_plic.c
> > +++ b/lib/utils/irqchip/fdt_irqchip_plic.c
> > @@ -12,54 +12,97 @@
> > #include <sbi/riscv_io.h>
> > #include <sbi/sbi_error.h>
> > #include <sbi/sbi_heap.h>
> > -#include <sbi/sbi_hartmask.h>
> > +#include <sbi/sbi_scratch.h>
> > #include <sbi_utils/fdt/fdt_helper.h>
> > #include <sbi_utils/irqchip/fdt_irqchip.h>
> > #include <sbi_utils/irqchip/plic.h>
> >
> > -static struct plic_data *plic_hartid2data[SBI_HARTMASK_MAX_BITS];
> > -static int plic_hartid2context[SBI_HARTMASK_MAX_BITS][2] = { { -1 } };
> > +static unsigned long plic_ptr_offset;
> > +
> > +#define plic_get_hart_data_ptr(__scratch) \
> > +({ \
> > + (void *)(*((ulong *)sbi_scratch_offset_ptr((__scratch), \
> > +   plic_ptr_offset))); \
>
> Why all the casting rather than just storing the pointer?

We are storing pointer value in scratch space as ulong but
sbi_scratch_offset_ptr() returns a void pointer to a location in
scratch space so we have to do the above casting for getting
the pointer stored in scratch space.

Thinking about this more, it is better to have generic helper
macros in sbi_scartch.h so that we don't have to define it
everywhere.

Regards,
Anup

>
> Jess
>
> > +})
> > +
> > +#define plic_set_hart_data_ptr(__scratch, __imsic) \
> > +do { \
> > + *((ulong *)sbi_scratch_offset_ptr((__scratch), plic_ptr_offset))\
> > + = (ulong)(__imsic); \
> > +} while (0)
> > +
> > +static unsigned long plic_mcontext_offset;
> > +
> > +#define plic_get_hart_mcontext(__scratch) \
> > +({ \
> > + long __ret = \
> > + *((long *)sbi_scratch_offset_ptr((__scratch), plic_mcontext_offset));\
> > + (__ret - 1); \
> > +})
> > +
> > +#define plic_set_hart_mcontext(__scratch, __mcontext) \
> > +do { \
> > + *((long *)sbi_scratch_offset_ptr((__scratch), plic_mcontext_offset))\
> > + = (long)(__mcontext + 1); \
> > +} while (0)
> > +
> > +static unsigned long plic_scontext_offset;
> > +
> > +#define plic_get_hart_scontext(__scratch) \
> > +({ \
> > + long __ret = \
> > + *((long *)sbi_scratch_offset_ptr((__scratch), plic_scontext_offset));\
> > + (__ret - 1); \
> > +})
> > +
> > +#define plic_set_hart_scontext(__scratch, __scontext) \
> > +do { \
> > + *((long *)sbi_scratch_offset_ptr((__scratch), plic_scontext_offset))\
> > + = (long)(__scontext + 1); \
> > +} while (0)
> >
> > void fdt_plic_priority_save(u8 *priority, u32 num)
> > {
> > - struct plic_data *plic = plic_hartid2data[current_hartid()];
> > + struct sbi_scratch *scratch = sbi_scratch_thishart_ptr();
> >
> > - plic_priority_save(plic, priority, num);
> > + plic_priority_save(plic_get_hart_data_ptr(scratch), priority, num);
> > }
> >
> > void fdt_plic_priority_restore(const u8 *priority, u32 num)
> > {
> > - struct plic_data *plic = plic_hartid2data[current_hartid()];
> > + struct sbi_scratch *scratch = sbi_scratch_thishart_ptr();
> >
> > - plic_priority_restore(plic, priority, num);
> > + plic_priority_restore(plic_get_hart_data_ptr(scratch), priority, num);
> > }
> >
> > void fdt_plic_context_save(bool smode, u32 *enable, u32 *threshold, u32 num)
> > {
> > - u32 hartid = current_hartid();
> > + struct sbi_scratch *scratch = sbi_scratch_thishart_ptr();
> >
> > - plic_context_save(plic_hartid2data[hartid],
> > -  plic_hartid2context[hartid][smode],
> > + plic_context_save(plic_get_hart_data_ptr(scratch),
> > +  smode ? plic_get_hart_scontext(scratch) :
> > +  plic_get_hart_mcontext(scratch),
> >  enable, threshold, num);
> > }
> >
> > void fdt_plic_context_restore(bool smode, const u32 *enable, u32 threshold,
> >      u32 num)
> > {
> > - u32 hartid = current_hartid();
> > + struct sbi_scratch *scratch = sbi_scratch_thishart_ptr();
> >
> > - plic_context_restore(plic_hartid2data[hartid],
> > -     plic_hartid2context[hartid][smode],
> > + plic_context_restore(plic_get_hart_data_ptr(scratch),
> > +     smode ? plic_get_hart_scontext(scratch) :
> > +     plic_get_hart_mcontext(scratch),
> >     enable, threshold, num);
> > }
> >
> > static int irqchip_plic_warm_init(void)
> > {
> > - u32 hartid = current_hartid();
> > + struct sbi_scratch *scratch = sbi_scratch_thishart_ptr();
> >
> > - return plic_warm_irqchip_init(plic_hartid2data[hartid],
> > -      plic_hartid2context[hartid][0],
> > -      plic_hartid2context[hartid][1]);
> > + return plic_warm_irqchip_init(plic_get_hart_data_ptr(scratch),
> > +      plic_get_hart_mcontext(scratch),
> > +      plic_get_hart_scontext(scratch));
> > }
> >
> > static int irqchip_plic_update_hartid_table(void *fdt, int nodeoff,
> > @@ -67,6 +110,7 @@ static int irqchip_plic_update_hartid_table(void *fdt, int nodeoff,
> > {
> > const fdt32_t *val;
> > u32 phandle, hwirq, hartid;
> > + struct sbi_scratch *scratch;
> > int i, err, count, cpu_offset, cpu_intc_offset;
> >
> > val = fdt_getprop(fdt, nodeoff, "interrupts-extended", &count);
> > @@ -90,16 +134,17 @@ static int irqchip_plic_update_hartid_table(void *fdt, int nodeoff,
> > if (err)
> > continue;
> >
> > - if (SBI_HARTMASK_MAX_BITS <= hartid)
> > + scratch = sbi_hartid_to_scratch(hartid);
> > + if (!scratch)
> > continue;
> >
> > - plic_hartid2data[hartid] = pd;
> > + plic_set_hart_data_ptr(scratch, pd);
> > switch (hwirq) {
> > case IRQ_M_EXT:
> > - plic_hartid2context[hartid][0] = i / 2;
> > + plic_set_hart_mcontext(scratch, i / 2);
> > break;
> > case IRQ_S_EXT:
> > - plic_hartid2context[hartid][1] = i / 2;
> > + plic_set_hart_scontext(scratch, i / 2);
> > break;
> > }
> > }
> > @@ -113,6 +158,24 @@ static int irqchip_plic_cold_init(void *fdt, int nodeoff,
> > int rc;
> > struct plic_data *pd;
> >
> > + if (!plic_ptr_offset) {
> > + plic_ptr_offset = sbi_scratch_alloc_offset(sizeof(ulong));
> > + if (!plic_ptr_offset)
> > + return SBI_ENOMEM;
> > + }
> > +
> > + if (!plic_mcontext_offset) {
> > + plic_mcontext_offset = sbi_scratch_alloc_offset(sizeof(long));
> > + if (!plic_mcontext_offset)
> > + return SBI_ENOMEM;
> > + }
> > +
> > + if (!plic_scontext_offset) {
> > + plic_scontext_offset = sbi_scratch_alloc_offset(sizeof(long));
> > + if (!plic_scontext_offset)
> > + return SBI_ENOMEM;
> > + }
> > +
> > pd = sbi_zalloc(sizeof(*pd));
> > if (!pd)
> > return SBI_ENOMEM;
> > @@ -152,7 +215,8 @@ static void thead_plic_plat_init(struct plic_data *pd)
> >
> > void thead_plic_restore(void)
> > {
> > - struct plic_data *plic = plic_hartid2data[current_hartid()];
> > + struct sbi_scratch *scratch = sbi_scratch_thishart_ptr();
> > + struct plic_data *plic = plic_get_hart_data_ptr(scratch);
> >
> > thead_plic_plat_init(plic);
> > }
> > --
> > 2.34.1
> >
> >
> > --
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>