Description of problem:

bt_ioremap does not calculate # of pages correctly for a boundary condition.
On systems with SMBIOS/DMI table length of 0x1001, only one page is mapped instead of two.  This causes a 'Unknown interrupt or fault at EIP 00000060 xxxxxx xxxxxx' error message to appear.

Version-Release number of selected component (if applicable):
5.x (reproduced on 5.7 and 5.8 beta kernels)

How reproducible: 
always


Steps to Reproduce:
1. BIOS with SMBIOS Table Length of 0x1001
2. Install RHEL5.x 32-bit kernel
3.
  
Actual results:
System spews error messages 'Unknown interrupt or fault at eip 00000060 xxxxxxxx xxxxxxxx'

Expected results:
System boots properly

Additional info:
This is a boundary condition, it only occurs if the SMBIOS (or any other function that calls bt_ioremap with size == 0xZ001)

Error is line #305: size gets set to 0x0fff instead of 0x1001

283 void __init *bt_ioremap(unsigned long phys_addr, unsigned long size)

284 {

285         unsigned long offset, last_addr;

286         unsigned int nrpages;

287         enum fixed_addresses idx;

288 

289         /* Don't allow wraparound or zero size */

290         last_addr = phys_addr + size - 1;

291         if (!size || last_addr < phys_addr)

292                 return NULL;

293 

294         /*

295          * Don't remap the low PCI/ISA area, it's always mapped..

296          */

297         if (phys_addr >= ISA_START_ADDRESS && last_addr < ISA_END_ADDRESS)

298                 return phys_to_virt(phys_addr);

299 

300         /*

301          * Mappings have to be page-aligned

302          */

303         offset = phys_addr & ~PAGE_MASK;

304         phys_addr &= PAGE_MASK;

305         size = PAGE_ALIGN(last_addr) - phys_addr;

306 

307         /*

308          * Mappings have to fit in the FIX_BTMAP area.

309          */

310         nrpages = size >> PAGE_SHIFT;