On Wed, Jun 22, 2011 at 12:44:45PM +0900, Magnus Damm wrote: > From: Magnus Damm <damm at opensource.se> > > Update the copy_oldmem_page() function to ioremap() only > when accessing memory that is outside the regular range > of system memory that is managed by the kernel. > > Without this patch a warning is triggered in the ARM-specific > ioremap implementation, see WARN_ON(pfn_valid()) in ioremap.c > > The copy_oldmem_page() function is used by the secondary crash > kernel to access memory using the /proc/vmcore code implemented > in fs/proc/vmcore.c. To pass information from the first kernel > to the secondary crash kernel a kernel command line option is > used to point out where the elf core hdr is located. > > The crash kernel is loaded through kexec-tools which also contains > code that reserves memory for the elfcorehdr= option. This memory > block is reserved _inside_ the main system memory of the secondary > kernel. The /proc/vmcore code in the secondary kernel is however > using copy_oldmem_page() to access both this elfcorehdr area and > the rest of the memory used by the the first kernel. > > So the copy_oldmem_page() function is used to access data that > may be located in system memory, or it may be outside. Always > using ioremap will not work, so this patch makes it conditional > based on pfn_valid(). > > For more details please look at the sh7372-based example here: > http://permalink.gmane.org/gmane.linux.ports.sh.devel/11502 > > Signed-off-by: Magnus Damm <damm at opensource.se> Reviewed-by: Simon Horman <horms at verge.net.au> > --- > > arch/arm/kernel/crash_dump.c | 14 ++++++++++---- > 1 file changed, 10 insertions(+), 4 deletions(-) > > --- 0001/arch/arm/kernel/crash_dump.c > +++ work/arch/arm/kernel/crash_dump.c 2011-06-18 20:59:49.000000000 +0900 > @@ -39,9 +39,13 @@ ssize_t copy_oldmem_page(unsigned long p > if (!csize) > return 0; > > - vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE); > - if (!vaddr) > - return -ENOMEM; > + if (pfn_valid(pfn)) { > + vaddr = phys_to_virt(pfn << PAGE_SHIFT); > + } else { > + vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE); > + if (!vaddr) > + return -ENOMEM; > + } > > if (userbuf) { > if (copy_to_user(buf, vaddr + offset, csize)) { > @@ -52,6 +56,8 @@ ssize_t copy_oldmem_page(unsigned long p > memcpy(buf, vaddr + offset, csize); > } > > - iounmap(vaddr); > + if (!pfn_valid(pfn)) > + iounmap(vaddr); > + > return csize; > } > -- > To unsubscribe from this list: send the line "unsubscribe linux-sh" in > the body of a message to majordomo at vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
