Messages in this thread Patch in this message | | | Subject | [PATCH 09/15] x86, fpu: add helper xfeature_enabled() instead of test_bit() | From | Dave Hansen <> | Date | Mon, 31 Aug 2015 15:20:54 -0700 |
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From: Dave Hansen <dave.hansen@linux.intel.com>
We currently use test_bit() in a few places to see if an xfeature is enabled. It ends up being a bit ugly because 'xfeatures_mask' is a u64 and test_bit wants an 'unsigned long' so it requires a cast. The *_bit() functions are also techincally atomic, which we have no need for here.
So, remove the test_bit()s and replace with the new xfeature_enabled() helper.
This also provides a central place to add a comment about the future need to support 'system xstates'.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: x86@kernel.org Cc: Borislav Petkov <bp@alien8.de> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: linux-kernel@vger.kernel.org ---
b/arch/x86/kernel/fpu/xstate.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-)
diff -puN arch/x86/kernel/fpu/xstate.c~use-xfeature_enabled arch/x86/kernel/fpu/xstate.c --- a/arch/x86/kernel/fpu/xstate.c~use-xfeature_enabled 2015-08-31 15:17:35.008910377 -0700 +++ b/arch/x86/kernel/fpu/xstate.c 2015-08-31 15:17:35.011910514 -0700 @@ -226,6 +226,16 @@ static void __init print_xstate_features } /* + * Note that in the future we will likely need a pair of + * functions here: one for user xstates and the other for + * system xstates. For now, they are the same. + */ +static int xfeature_enabled(enum xfeature xfeature) +{ + return !!(xfeatures_mask & (1UL << xfeature)); +} + +/* * This function sets up offsets and sizes of all extended states in * xsave area. This supports both standard format and compacted format * of the xsave aread. @@ -245,7 +255,7 @@ static void __init setup_xstate_comp(voi if (!cpu_has_xsaves) { for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) { - if (test_bit(i, (unsigned long *)&xfeatures_mask)) { + if (xfeature_enabled(i)) { xstate_comp_offsets[i] = xstate_offsets[i]; xstate_comp_sizes[i] = xstate_sizes[i]; } @@ -257,7 +267,7 @@ static void __init setup_xstate_comp(voi FXSAVE_SIZE + XSAVE_HDR_SIZE; for (i = FIRST_EXTENDED_XFEATURE; i < XFEATURE_MAX; i++) { - if (test_bit(i, (unsigned long *)&xfeatures_mask)) + if (xfeature_enabled(i)) xstate_comp_sizes[i] = xstate_sizes[i]; else xstate_comp_sizes[i] = 0; @@ -319,7 +329,7 @@ static unsigned int __init calculate_xst calculated_xstate_size = FXSAVE_SIZE + XSAVE_HDR_SIZE; for (i = FIRST_EXTENDED_XFEATURE; i < 64; i++) { - if (test_bit(i, (unsigned long *)&xfeatures_mask)) { + if (xfeature_enabled(i)) { cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx); calculated_xstate_size += eax; } _
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