Merge tag 'riscv-for-linus-5.8-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

Pull RISC-V updates from Palmer Dabbelt:

 - The remainder of the code necessary to support the Kendryte K210:

     * Support for building device trees into the kernel, as the K210
       doesn't have a bootloader that provides one

     * A K210 device tree and the associated defconfig update

     * Support for skipping PMP initialization on systems that trap on
       PMP accesses rather than treating them as WARL

 - Support for KGDB

 - Improvements to text patching

 - Some cleanups to the SiFive L2 cache driver

* tag 'riscv-for-linus-5.8-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  soc: sifive: l2 cache: Mark l2_get_priv_group as static
  soc: sifive: l2 cache: Eliminate an unsigned zero compare warning
  riscv: Add support to determine no. of L2 cache way enabled
  riscv: cacheinfo: Implement cache_get_priv_group with a generic ops structure
  riscv: Use text_mutex instead of patch_lock
  riscv: Use NOKPROBE_SYMBOL() instead of __krpobes annotation
  riscv: Remove the 'riscv_' prefix of function name
  riscv: Add SW single-step support for KDB
  riscv: Use the XML target descriptions to report 3 system registers
  riscv: Add KGDB support
  kgdb: Add kgdb_has_hit_break function
  RISC-V: Skip setting up PMPs on traps
  riscv: K210: Update defconfig
  riscv: K210: Add a built-in device tree
  riscv: Allow device trees to be built into the kernel

1 files changed, 10 insertions, 1 deletions

diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 98a406474e7d..7ed1b22950fd 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -161,11 +161,20 @@ ENTRY(_start_kernel)
 	/* Reset all registers except ra, a0, a1 */
 	call reset_regs
 
-	/* Setup a PMP to permit access to all of memory. */
+	/*
+	 * Setup a PMP to permit access to all of memory.  Some machines may
+	 * not implement PMPs, so we set up a quick trap handler to just skip
+	 * touching the PMPs on any trap.
+	 */
+	la a0, pmp_done
+	csrw CSR_TVEC, a0
+
 	li a0, -1
 	csrw CSR_PMPADDR0, a0
 	li a0, (PMP_A_NAPOT | PMP_R | PMP_W | PMP_X)
 	csrw CSR_PMPCFG0, a0
+.align 2
+pmp_done:
 
 	/*
 	 * The hartid in a0 is expected later on, and we have no firmware