From 184fc7781500b64586c94c50de6e61539046dbcd Mon Sep 17 00:00:00 2001 From: Keir Fraser Date: Wed, 5 Dec 2007 10:34:15 +0000 Subject: [PATCH] x86_emulate: EFLAGS.PF only reflects least-significant byte of result, so even_parity() can return to its original prototype. Signed-off-by: Keir Fraser --- xen/arch/x86/x86_emulate.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/xen/arch/x86/x86_emulate.c b/xen/arch/x86/x86_emulate.c index 20f6cec5b5..66ea5a8454 100644 --- a/xen/arch/x86/x86_emulate.c +++ b/xen/arch/x86/x86_emulate.c @@ -508,11 +508,14 @@ do { \ } \ }) -/* Given longword has even parity (even number of 1s)? */ -static int even_parity(unsigned long v) +/* + * Given byte has even parity (even number of 1s)? SDM Vol. 1 Sec. 3.4.3.1, + * "Status Flags": EFLAGS.PF reflects parity of least-sig. byte of result only. + */ +static int even_parity(uint8_t v) { - asm ( "test %0,%0; setp %b0" : "=a" (v) : "0" (v) ); - return (uint8_t)v; + asm ( "test %b0,%b0; setp %b0" : "=a" (v) : "0" (v) ); + return v; } /* Update address held in a register, based on addressing mode. */ @@ -1915,7 +1918,7 @@ x86_emulate( _regs.eflags &= ~(EFLG_SF|EFLG_ZF|EFLG_PF); _regs.eflags |= ((uint8_t)_regs.eax == 0) ? EFLG_ZF : 0; _regs.eflags |= (( int8_t)_regs.eax < 0) ? EFLG_SF : 0; - _regs.eflags |= even_parity((uint8_t)_regs.eax) ? EFLG_PF : 0; + _regs.eflags |= even_parity(_regs.eax) ? EFLG_PF : 0; break; } @@ -1939,7 +1942,7 @@ x86_emulate( _regs.eflags &= ~(EFLG_SF|EFLG_ZF|EFLG_PF); _regs.eflags |= ((uint8_t)_regs.eax == 0) ? EFLG_ZF : 0; _regs.eflags |= (( int8_t)_regs.eax < 0) ? EFLG_SF : 0; - _regs.eflags |= even_parity((uint8_t)_regs.eax) ? EFLG_PF : 0; + _regs.eflags |= even_parity(_regs.eax) ? EFLG_PF : 0; break; } @@ -2405,7 +2408,7 @@ x86_emulate( _regs.eflags &= ~(EFLG_SF|EFLG_ZF|EFLG_PF); _regs.eflags |= ((uint8_t)_regs.eax == 0) ? EFLG_ZF : 0; _regs.eflags |= (( int8_t)_regs.eax < 0) ? EFLG_SF : 0; - _regs.eflags |= even_parity((uint8_t)_regs.eax) ? EFLG_PF : 0; + _regs.eflags |= even_parity(_regs.eax) ? EFLG_PF : 0; break; } @@ -2417,7 +2420,7 @@ x86_emulate( _regs.eflags &= ~(EFLG_SF|EFLG_ZF|EFLG_PF); _regs.eflags |= ((uint8_t)_regs.eax == 0) ? EFLG_ZF : 0; _regs.eflags |= (( int8_t)_regs.eax < 0) ? EFLG_SF : 0; - _regs.eflags |= even_parity((uint8_t)_regs.eax) ? EFLG_PF : 0; + _regs.eflags |= even_parity(_regs.eax) ? EFLG_PF : 0; break; } -- 2.30.2