Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'x86_fred_for_v7.1_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 FRED updates from Borislav Petkov:
"We made the FRED support an opt-in initially out of fear of it
breaking machines left and right in the case of a hw bug in the first
generation of machines supporting it.
Now that that the FRED code has seen a lot of hammering, flip the
logic to be opt-out as is the usual case with new hw features"
* tag 'x86_fred_for_v7.1_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/fred: Remove kernel log message when initializing exceptions
x86/fred: Enable FRED by default
+4
-7
+2
-2
Documentation/admin-guide/kernel-parameters.txt
+2
-2
Documentation/admin-guide/kernel-parameters.txt
···
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fred= [X86-64]
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Enable/disable Flexible Return and Event Delivery.
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Format: { on | off }
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-
on: enable FRED when it's present.
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-
off: disable FRED, the default setting.
1768
+
on: enable FRED when it's present, the default setting.
1769
+
off: disable FRED.
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ftrace=[tracer]
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[FTRACE] will set and start the specified tracer
+1
-1
arch/x86/Kconfig
+1
-1
arch/x86/Kconfig
···
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554
bool "Flexible Return and Event Delivery"
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depends on X86_64
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help
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-
When enabled, try to use Flexible Return and Event Delivery
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+
When enabled, use Flexible Return and Event Delivery
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instead of the legacy SYSCALL/SYSENTER/IDT architecture for
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ring transitions and exception/interrupt handling if the
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system supports it.
+1
-1
arch/x86/kernel/cpu/common.c
+1
-1
arch/x86/kernel/cpu/common.c
···
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/* Minimize the gap between FRED is available and available but disabled. */
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arglen = cmdline_find_option(boot_command_line, "fred", arg, sizeof(arg));
1764
-
if (arglen != 2 || strncmp(arg, "on", 2))
1764
+
if (arglen == 3 && !strncmp(arg, "off", 3))
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1765
setup_clear_cpu_cap(X86_FEATURE_FRED);
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arglen = cmdline_find_option(boot_command_line, "clearcpuid", arg, sizeof(arg));
-3
arch/x86/kernel/fred.c
-3
arch/x86/kernel/fred.c
···
27
27
28
28
void cpu_init_fred_exceptions(void)
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{
30
-
/* When FRED is enabled by default, remove this log message */
31
-
pr_info("Initialize FRED on CPU%d\n", smp_processor_id());
32
-
33
30
/*
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31
* If a kernel event is delivered before a CPU goes to user level for
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32
* the first time, its SS is NULL thus NULL is pushed into the SS field