Messages in this thread | | | Date | Tue, 24 Jun 2014 13:31:25 -0400 | From | Vivek Goyal <> | Subject | Re: [PATCH 11/13] kexec-bzImage: Support for loading bzImage using 64bit entry |
| |
On Sun, Jun 15, 2014 at 06:35:15PM +0200, Borislav Petkov wrote:
[..] > > +int kexec_setup_initrd(struct boot_params *params, > > + unsigned long initrd_load_addr, unsigned long initrd_len) > > +{ > > + params->hdr.ramdisk_image = initrd_load_addr & 0xffffffffUL; > > + params->hdr.ramdisk_size = initrd_len & 0xffffffffUL; > > We have more readable GENMASK* macros for contiguous masks. This one > will then look like: > > params->hdr.ramdisk_image = initrd_load_addr & GENMASK(31, 0); > params->hdr.ramdisk_size = initrd_len & GENMASK(31, 0); > > and this way we know exactly about which bits are we talking about. :)
[ CC gong.chen@linux.intel.com ]
GENMASK(31,0) outputs compilation warning.
arch/x86/kernel/machine_kexec.c: In function ‘kexec_setup_initrd’: arch/x86/kernel/machine_kexec.c:30:2: warning: left shift count >= width of type [enabled by default] params->hdr.ramdisk_image = initrd_load_addr & GENMASK(31, 0); ^ arch/x86/kernel/machine_kexec.c:31:2: warning: left shift count >= width of type [enabled by default] params->hdr.ramdisk_size = initrd_len & GENMASK(31, 0); ^ arch/x86/kernel/machine_kexec.c: In function ‘kexec_setup_cmdline’: arch/x86/kernel/machine_kexec.c:52:2: warning: left shift count >= width of type [enabled by default] cmdline_low_32 = cmdline_ptr_phys & GENMASK(31, 0);
I think problem is that we shift 1 by 32 bits in this case (31 - 0 + 1) and that overflows the size of unsigned. So there is this corner case where it does not seem to work (or atleast outputs warning).
Thanks Vivek -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |