mirror of
https://github.com/torvalds/linux.git
synced 2024-12-17 08:31:39 +00:00
32231879f6
Now that all the FPU init function call dependencies are cleaned up we can propagate __init annotations deeper. This shrinks the runtime size of the kernel a bit, and also addresses a few section warnings. Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
72 lines
1.4 KiB
C
72 lines
1.4 KiB
C
/*
|
|
* x86 FPU bug checks:
|
|
*/
|
|
#include <asm/fpu/internal.h>
|
|
|
|
/*
|
|
* Boot time CPU/FPU FDIV bug detection code:
|
|
*/
|
|
|
|
static double __initdata x = 4195835.0;
|
|
static double __initdata y = 3145727.0;
|
|
|
|
/*
|
|
* This used to check for exceptions..
|
|
* However, it turns out that to support that,
|
|
* the XMM trap handlers basically had to
|
|
* be buggy. So let's have a correct XMM trap
|
|
* handler, and forget about printing out
|
|
* some status at boot.
|
|
*
|
|
* We should really only care about bugs here
|
|
* anyway. Not features.
|
|
*/
|
|
static void __init check_fpu(void)
|
|
{
|
|
u32 cr0_saved;
|
|
s32 fdiv_bug;
|
|
|
|
/* We might have CR0::TS set already, clear it: */
|
|
cr0_saved = read_cr0();
|
|
write_cr0(cr0_saved & ~X86_CR0_TS);
|
|
|
|
kernel_fpu_begin();
|
|
|
|
/*
|
|
* trap_init() enabled FXSR and company _before_ testing for FP
|
|
* problems here.
|
|
*
|
|
* Test for the divl bug: http://en.wikipedia.org/wiki/Fdiv_bug
|
|
*/
|
|
__asm__("fninit\n\t"
|
|
"fldl %1\n\t"
|
|
"fdivl %2\n\t"
|
|
"fmull %2\n\t"
|
|
"fldl %1\n\t"
|
|
"fsubp %%st,%%st(1)\n\t"
|
|
"fistpl %0\n\t"
|
|
"fwait\n\t"
|
|
"fninit"
|
|
: "=m" (*&fdiv_bug)
|
|
: "m" (*&x), "m" (*&y));
|
|
|
|
kernel_fpu_end();
|
|
|
|
write_cr0(cr0_saved);
|
|
|
|
if (fdiv_bug) {
|
|
set_cpu_bug(&boot_cpu_data, X86_BUG_FDIV);
|
|
pr_warn("Hmm, FPU with FDIV bug\n");
|
|
}
|
|
}
|
|
|
|
void __init fpu__init_check_bugs(void)
|
|
{
|
|
/*
|
|
* kernel_fpu_begin/end() in check_fpu() relies on the patched
|
|
* alternative instructions.
|
|
*/
|
|
if (cpu_has_fpu)
|
|
check_fpu();
|
|
}
|