Hi Eugeniu,
On Mon, Aug 27, 2018 at 7:19 AM Eugeniu Rosca roscaeugeniu@gmail.com wrote:
Fix the following UBSAN report:
UBSAN: Undefined behaviour in arch/x86/cpu/lapic.c:73:14 left shift of 1048575 by 12 places cannot be represented in type 'int' ======================================================================
Steps to reproduce the above:
- echo CONFIG_UBSAN=y >> configs/qemu-x86_defconfig
- make ARCH=x86 qemu-x86_defconfig all
- qemu-system-i386 --version QEMU emulator version 2.5.0 (Debian 1:2.5+dfsg-5ubuntu10.31)
- qemu-system-i386 --nographic -bios u-boot.rom
Fixes: 98568f0fa96b ("x86: Import MSR/MTRR code from Linux") Signed-off-by: Eugeniu Rosca erosca@de.adit-jv.com
Changes in v2:
- None. Newly pushed.
arch/x86/include/asm/msr-index.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h index 9c1dbe61d596..d8b7b8013c74 100644 --- a/arch/x86/include/asm/msr-index.h +++ b/arch/x86/include/asm/msr-index.h @@ -370,7 +370,7 @@ #define MSR_IA32_APICBASE 0x0000001b #define MSR_IA32_APICBASE_BSP (1<<8) #define MSR_IA32_APICBASE_ENABLE (1<<11) -#define MSR_IA32_APICBASE_BASE (0xfffff<<12) +#define MSR_IA32_APICBASE_BASE (0xfffffUL << 12)
I don't understand why such warnings is emitted: "left shift of 1048575 by 12 places cannot be represented in type 'int'"
Compilers don't complain this code and Linux kernel has the same definition here.
Regards, Bin