[PATCH 7/15] misc: Make x86 doublefault handling optional

Matt Mackall
2005-11-11T08:36:40Z

This adds configurable support for doublefault reporting on x86

add/remove: 0/3 grow/shrink: 0/1 up/down: 0/-13048 (-13048)
function old new delta
cpu_init 846 786 -60
doublefault_fn 188 - -188
doublefault_stack 4096 - -4096
doublefault_tss 8704 - -8704

Signed-off-by: Matt Mackall <mpm@selenic.com>

Index: 2.6.14-misc/arch/i386/kernel/Makefile
===================================================================
--- 2.6.14-misc.orig/arch/i386/kernel/Makefile 2005-10-27 17:02:08.000000000 -0700
+++ 2.6.14-misc/arch/i386/kernel/Makefile 2005-11-09 11:19:46.000000000 -0800
@@ -7,7 +7,7 @@ extra-y := head.o init_task.o vmlinux.ld
obj-y := process.o semaphore.o signal.o entry.o traps.o irq.o vm86.o \
ptrace.o time.o ioport.o ldt.o setup.o i8259.o sys_i386.o \
pci-dma.o i386_ksyms.o i387.o dmi_scan.o bootflag.o \
- doublefault.o quirks.o i8237.o
+ quirks.o i8237.o

obj-y += cpu/
obj-y += timers/
@@ -33,6 +33,7 @@ obj-y += sysenter.o vsyscall.o
obj-$(CONFIG_ACPI_SRAT) += srat.o
obj-$(CONFIG_HPET_TIMER) += time_hpet.o
obj-$(CONFIG_EFI) += efi.o efi_stub.o
+obj-$(CONFIG_DOUBLEFAULT) += doublefault.o
obj-$(CONFIG_EARLY_PRINTK) += early_printk.o

EXTRA_AFLAGS := -traditional
Index: 2.6.14-misc/arch/i386/kernel/cpu/common.c
===================================================================
--- 2.6.14-misc.orig/arch/i386/kernel/cpu/common.c 2005-11-01 10:54:31.000000000 -0800
+++ 2.6.14-misc/arch/i386/kernel/cpu/common.c 2005-11-09 11:19:46.000000000 -0800
@@ -628,8 +628,10 @@ void __devinit cpu_init(void)
load_TR_desc();
load_LDT(&init_mm.context);

+#ifdef CONFIG_DOUBLEFAULT
/* Set up doublefault TSS pointer in the GDT */
__set_tss_desc(cpu, GDT_ENTRY_DOUBLEFAULT_TSS, &doublefault_tss);
+#endif

/* Clear %fs and %gs. */
asm volatile ("xorl %eax, %eax; movl %eax, %fs; movl %eax, %gs");
Index: 2.6.14-misc/init/Kconfig
===================================================================
--- 2.6.14-misc.orig/init/Kconfig 2005-11-01 10:54:33.000000000 -0800
+++ 2.6.14-misc/init/Kconfig 2005-11-09 11:19:46.000000000 -0800
@@ -315,6 +315,15 @@ config BUG
option for embedded systems with no facilities for reporting errors.
Just say Y.

+config DOUBLEFAULT
+ depends X86
+ default y if X86
+ bool "Enable doublefault exception handler" if EMBEDDED
+ help
+ This option allows trapping of rare doublefault exceptions that
+ would otherwise cause a system to silently reboot. Disabling this
+ option saves about 4k.
+
config BASE_FULL
default y
bool "Enable full-sized data structures for core" if EMBEDDED