Linux Virtualization - Apr 2007 - [PATCH] Define EFLAGS_IF

There is now more than one place where we use the fact that bit 9 of
eflags is the interrupt-enabled flag, so define EFLAGS_IF.  We make it
512 so it can be used in asm, too.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

--- a/arch/i386/lguest/lguest.c
+++ b/arch/i386/lguest/lguest.c
@@ -107,9 +107,8 @@ static void fastcall irq_disable(void)
 
 static void fastcall irq_enable(void)
 {
-	/* Linux i386 code expects bit 9 set. */
 	/* FIXME: Check if interrupt pending... */
-	lguest_data.irq_enabled = 512;
+	lguest_data.irq_enabled = EFLAGS_IF;
 }
 
 static void fastcall lguest_load_gdt(const struct Xgt_desc_struct *desc)
@@ -394,7 +393,7 @@ static fastcall void lguest_write_idt_en
 	extern const char start_##name[], end_##name[];		\
 	asm("start_" #name ": " code "; end_" #name
":")
 DEF_LGUEST(cli, "movl $0," LGUEST_IRQ);
-DEF_LGUEST(sti, "movl $512," LGUEST_IRQ);
+DEF_LGUEST(sti, "movl $"__stringify(EFLAGS_IF)","
LGUEST_IRQ);
 DEF_LGUEST(popf, "movl %eax," LGUEST_IRQ);
 DEF_LGUEST(pushf, "movl " LGUEST_IRQ ",%eax");
 DEF_LGUEST(pushf_cli, "movl " LGUEST_IRQ ",%eax; movl $0,"
LGUEST_IRQ);
==================================================================---
a/include/asm-i386/irqflags.h
+++ b/include/asm-i386/irqflags.h
@@ -87,6 +87,9 @@ static inline unsigned long __raw_local_
 #endif /* __ASSEMBLY__ */
 #endif /* CONFIG_PARAVIRT */
 
+/* Bit 9 of eflags means interrupts are enabled: a raw int for asm. */
+#define EFLAGS_IF 512
+
 #ifndef __ASSEMBLY__
 #define raw_local_save_flags(flags) \
 		do { (flags) = __raw_local_save_flags(); } while (0)
@@ -96,7 +99,7 @@ static inline unsigned long __raw_local_
 
 static inline int raw_irqs_disabled_flags(unsigned long flags)
 {
-	return !(flags & (1 << 9));
+	return !(flags & EFLAGS_IF);
 }
 
 static inline int raw_irqs_disabled(void)

On Thu, 2007-03-22 at 14:16 +1100, Rusty Russell wrote:
> There is now more than one place where we use the fact that bit 9 of
> eflags is the interrupt-enabled flag, so define EFLAGS_IF.  We make it
> 512 so it can be used in asm, too.
Belay this: there's a X86_EFLAGS_IF in asm/processor.h which we should
use.  Will send patch.

Thanks to Jeremy Fitzhardinge for the clue.

Rusty.

Rusty Russell wrote:
> There is now more than one place where we use the fact that bit 9 of
> eflags is the interrupt-enabled flag, so define EFLAGS_IF.  We make it
> 512 so it can be used in asm, too.
How about defining all the other EFLAGS in one place?

	-hpa