diff --git a/arch/x86/src/qemu/qemu_fullcontextrestore.S b/arch/x86/src/qemu/qemu_fullcontextrestore.S index 7d25e9072e..9a1e1e64e4 100644 --- a/arch/x86/src/qemu/qemu_fullcontextrestore.S +++ b/arch/x86/src/qemu/qemu_fullcontextrestore.S @@ -61,14 +61,24 @@ /* Trace macros, use like trace 'i' to print char to serial port. */ - .macro trace, ch + .macro chout, addr, ch #ifdef CONFIG_DEBUG - mov $0x3f8, %dx + mov $\addr, %dx mov $\ch, %al out %al, %dx #endif .endm + .macro trace, ch +#ifdef CONFIG_DEBUG + push %eax + push %edx + chout 0x3f8, \ch + pop %edx + pop %eax +#endif + .endm + /************************************************************************** * Public Functions **************************************************************************/ @@ -151,5 +161,5 @@ up_fullcontextrestore: popl %eax iret .size up_fullcontextrestore, . - up_fullcontextrestore - .end + .end diff --git a/arch/x86/src/qemu/qemu_saveusercontext.S b/arch/x86/src/qemu/qemu_saveusercontext.S index ffa1cf7f62..e9a98b3315 100644 --- a/arch/x86/src/qemu/qemu_saveusercontext.S +++ b/arch/x86/src/qemu/qemu_saveusercontext.S @@ -57,14 +57,24 @@ /* Trace macros, use like trace 'i' to print char to serial port. */ - .macro trace, ch + .macro chout, addr, ch #ifdef CONFIG_DEBUG - mov $0x3f8, %dx + mov $\addr, %dx mov $\ch, %al out %al, %dx #endif .endm + .macro trace, ch +#ifdef CONFIG_DEBUG + push %eax + push %edx + chout 0x3f8, \ch + pop %edx + pop %eax +#endif + .endm + /************************************************************************** * .text **************************************************************************/ @@ -132,15 +142,26 @@ up_saveusercontext: movl %ebp, (4*REG_EBP)(%eax) - /* Get and save the interrupt state */ - - pushf - pop %ecx - movl %ecx, (4*REG_EFLAGS)(%eax) + /* Save EAX=1. This will be the "apparent" return value from this + * function when context is switch back to this thread. The non-zero + * return value is the indication that we have been resumed. + */ - /* And return 0. 'ret' will remove the EIP from the top of the stack. */ + movl $1, (4*REG_EAX)(%eax) - xorl %eax, %eax + /* Get and save the interrupt state */ + + pushf + pop %ecx + movl %ecx, (4*REG_EFLAGS)(%eax) + + /* And return 0 -- The zero return value is the indication that that + * this is the original, "true" return from the function. + * + * 'ret' will remove the EIP from the top of the stack. + */ + + xorl %eax, %eax ret .size up_saveusercontext, . - up_saveusercontext - .end + .end