This patch ensure pmpcfg and pmpaddr comply with WARL constraints.
When the PMP granularity is greater than 4 bytes, NA4 mode is not valid
per the spec and will be silently ignored.
According to the spec, changing pmpcfg.A only affects the "read" value
of pmpaddr. When G > 2 and pmpcfg.A is NAPOT, bits pmpaddr[G-2:0] read
as all ones. When G > 1 and pmpcfg.A is OFF or TOR, bits pmpaddr[G-1:0]
read as all zeros. This allows software to read back the correct
granularity value.
In addition, when updating the PMP address rule in TOR mode,
the start and end addresses of the PMP region should be aligned
to the PMP granularity. (The current SPEC only state in TOR mode
that bits pmpaddr[G-1:0] do not affect the TOR address-matching logic.)
Signed-off-by: Jay Chang <jay.chang@sifive.com>
Reviewed-by: Frank Chang <frank.chang@sifive.com>
Reviewed-by: Jim Shu <jim.shu@sifive.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20251022024141.42178-3-jay.chang@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
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