Merge tag 'riscv-for-linus-6.1-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

Pull RISC-V fixes from Palmer Dabbelt:

 - build fix for the NR_CPUS Kconfig SBI version dependency

 - fixes to early memory initialization, to fix page permissions in EFI
   and post-initmem-free

 - build fix for the VDSO, to avoid trying to profile the VDSO functions

 - fixes for kexec crash handling, to fix multi-core and interrupt
   related initialization inside the crash kernel

 - fix for a race condition when handling multiple concurrect kernel
   stack overflows

* tag 'riscv-for-linus-6.1-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: kexec: Fixup crash_smp_send_stop without multi cores
  riscv: kexec: Fixup irq controller broken in kexec crash path
  riscv: mm: Proper page permissions after initmem free
  riscv: vdso: fix section overlapping under some conditions
  riscv: fix race when vmap stack overflow
  riscv: Sync efi page table's kernel mappings before switching
  riscv: Fix NR_CPUS range conditions

1 files changed, 13 insertions, 0 deletions

diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index b9eda3fcbd6d..186abd146eaf 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -404,6 +404,19 @@ handle_syscall_trace_exit:
 
 #ifdef CONFIG_VMAP_STACK
 handle_kernel_stack_overflow:
+	/*
+	 * Takes the psuedo-spinlock for the shadow stack, in case multiple
+	 * harts are concurrently overflowing their kernel stacks.  We could
+	 * store any value here, but since we're overflowing the kernel stack
+	 * already we only have SP to use as a scratch register.  So we just
+	 * swap in the address of the spinlock, as that's definately non-zero.
+	 *
+	 * Pairs with a store_release in handle_bad_stack().
+	 */
+1:	la sp, spin_shadow_stack
+	REG_AMOSWAP_AQ sp, sp, (sp)
+	bnez sp, 1b
+
 	la sp, shadow_stack
 	addi sp, sp, SHADOW_OVERFLOW_STACK_SIZE