text: // SPDX-License-Identifier: GPL-2.0
  
  #include <linux/types.h>
  #include <linux/mmdebug.h>
  #include <linux/mm.h>
  #include <asm/page.h>
  #include <asm/sections.h>
  
  phys_addr_t __virt_to_phys(unsigned long x)
  {
  	phys_addr_t y = x - PAGE_OFFSET;
  
  	/*
  	 * Boundary checking aginst the kernel linear mapping space.
  	 */
  	WARN(y >= KERN_VIRT_SIZE,
  	     "virt_to_phys used for non-linear address: %pK (%pS)\n",
  	     (void *)x, (void *)x);
  
  	return __va_to_pa_nodebug(x);
  }
  EXPORT_SYMBOL(__virt_to_phys);
  
  phys_addr_t __phys_addr_symbol(unsigned long x)
  {
  	unsigned long kernel_start = (unsigned long)kernel_virt_addr;
  	unsigned long kernel_end = (unsigned long)_end;
  
  	/*
  	 * Boundary checking aginst the kernel image mapping.
  	 * __pa_symbol should only be used on kernel symbol addresses.
  	 */
  	VIRTUAL_BUG_ON(x < kernel_start || x > kernel_end);
  
  	return __va_to_pa_nodebug(x);
  }
  EXPORT_SYMBOL(__phys_addr_symbol);
  