From d3b5491897456739c6dc21c604ef8bc28e294bfc Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 15 May 2014 18:19:17 +0200 Subject: [PATCH] target-i386: rework CPL checks during task switch, preparing for next patch During task switch, all of CS.DPL, CS.RPL, SS.DPL must match (in addition to all the other requirements) and will be the new CPL. So far this worked by carefully setting the CS selector and flags before doing the task switch; but this will not work once we get the CPL from SS.DPL. Temporarily assume that the CPL comes from CS.RPL during task switch to a protected-mode task, until the descriptor of SS is loaded. Tested-by: Kevin O'Connor Signed-off-by: Paolo Bonzini --- target-i386/seg_helper.c | 23 +++++++++-------------- 1 file changed, 9 insertions(+), 14 deletions(-) diff --git a/target-i386/seg_helper.c b/target-i386/seg_helper.c index 6f7efeeaa0..0f00aede08 100644 --- a/target-i386/seg_helper.c +++ b/target-i386/seg_helper.c @@ -135,11 +135,10 @@ static inline void get_ss_esp_from_tss(CPUX86State *env, uint32_t *ss_ptr, } } -/* XXX: merge with load_seg() */ -static void tss_load_seg(CPUX86State *env, int seg_reg, int selector) +static void tss_load_seg(CPUX86State *env, int seg_reg, int selector, int cpl) { uint32_t e1, e2; - int rpl, dpl, cpl; + int rpl, dpl; if ((selector & 0xfffc) != 0) { if (load_segment(env, &e1, &e2, selector) != 0) { @@ -150,18 +149,13 @@ static void tss_load_seg(CPUX86State *env, int seg_reg, int selector) } rpl = selector & 3; dpl = (e2 >> DESC_DPL_SHIFT) & 3; - cpl = env->hflags & HF_CPL_MASK; if (seg_reg == R_CS) { if (!(e2 & DESC_CS_MASK)) { raise_exception_err(env, EXCP0A_TSS, selector & 0xfffc); } - /* XXX: is it correct? */ if (dpl != rpl) { raise_exception_err(env, EXCP0A_TSS, selector & 0xfffc); } - if ((e2 & DESC_C_MASK) && dpl > rpl) { - raise_exception_err(env, EXCP0A_TSS, selector & 0xfffc); - } } else if (seg_reg == R_SS) { /* SS must be writable data */ if ((e2 & DESC_CS_MASK) || !(e2 & DESC_W_MASK)) { @@ -448,12 +442,13 @@ static void switch_tss(CPUX86State *env, int tss_selector, /* load the segments */ if (!(new_eflags & VM_MASK)) { - tss_load_seg(env, R_CS, new_segs[R_CS]); - tss_load_seg(env, R_SS, new_segs[R_SS]); - tss_load_seg(env, R_ES, new_segs[R_ES]); - tss_load_seg(env, R_DS, new_segs[R_DS]); - tss_load_seg(env, R_FS, new_segs[R_FS]); - tss_load_seg(env, R_GS, new_segs[R_GS]); + int cpl = new_segs[R_CS] & 3; + tss_load_seg(env, R_CS, new_segs[R_CS], cpl); + tss_load_seg(env, R_SS, new_segs[R_SS], cpl); + tss_load_seg(env, R_ES, new_segs[R_ES], cpl); + tss_load_seg(env, R_DS, new_segs[R_DS], cpl); + tss_load_seg(env, R_FS, new_segs[R_FS], cpl); + tss_load_seg(env, R_GS, new_segs[R_GS], cpl); } /* check that env->eip is in the CS segment limits */