Module Name: src Committed By: maxv Date: Sun Mar 24 15:58:32 UTC 2019
Modified Files: src/sys/arch/amd64/amd64: machdep.c netbsd32_machdep.c src/sys/compat/linux32/arch/amd64: linux32_machdep.c Log Message: Disable preemption when setting PCB_COMPAT32, to prevent a context switch before cpu_fsgs_reload() finishes, otherwise we write garbage in the GDT. On NetBSD-current it is harmless, however in NetBSD-8 it might cause panics, because NetBSD-8 uses the old SegRegs model and under this model we reload %fs and %gs during switches. To generate a diff of this commit: cvs rdiff -u -r1.328 -r1.329 src/sys/arch/amd64/amd64/machdep.c cvs rdiff -u -r1.119 -r1.120 src/sys/arch/amd64/amd64/netbsd32_machdep.c cvs rdiff -u -r1.43 -r1.44 \ src/sys/compat/linux32/arch/amd64/linux32_machdep.c Please note that diffs are not public domain; they are subject to the copyright notices on the relevant files.
Modified files: Index: src/sys/arch/amd64/amd64/machdep.c diff -u src/sys/arch/amd64/amd64/machdep.c:1.328 src/sys/arch/amd64/amd64/machdep.c:1.329 --- src/sys/arch/amd64/amd64/machdep.c:1.328 Sun Mar 24 13:15:42 2019 +++ src/sys/arch/amd64/amd64/machdep.c Sun Mar 24 15:58:32 2019 @@ -1,4 +1,4 @@ -/* $NetBSD: machdep.c,v 1.328 2019/03/24 13:15:42 maxv Exp $ */ +/* $NetBSD: machdep.c,v 1.329 2019/03/24 15:58:32 maxv Exp $ */ /* * Copyright (c) 1996, 1997, 1998, 2000, 2006, 2007, 2008, 2011 @@ -110,7 +110,7 @@ */ #include <sys/cdefs.h> -__KERNEL_RCSID(0, "$NetBSD: machdep.c,v 1.328 2019/03/24 13:15:42 maxv Exp $"); +__KERNEL_RCSID(0, "$NetBSD: machdep.c,v 1.329 2019/03/24 15:58:32 maxv Exp $"); #include "opt_modular.h" #include "opt_user_ldt.h" @@ -2237,12 +2237,12 @@ cpu_segregs32_zero(struct lwp *l) struct pcb *pcb; uint64_t zero = 0; + KASSERT(kpreempt_disabled()); KASSERT(l->l_proc->p_flag & PK_32); KASSERT(l == curlwp); pcb = lwp_getpcb(l); - kpreempt_disable(); tf->tf_fs = 0; tf->tf_gs = 0; setds(GSEL(GUDATA32_SEL, SEL_UPL)); @@ -2253,7 +2253,6 @@ cpu_segregs32_zero(struct lwp *l) pcb->pcb_gs = 0; update_descriptor(&curcpu()->ci_gdt[GUFS_SEL], &zero); update_descriptor(&curcpu()->ci_gdt[GUGS_SEL], &zero); - kpreempt_enable(); } /* Index: src/sys/arch/amd64/amd64/netbsd32_machdep.c diff -u src/sys/arch/amd64/amd64/netbsd32_machdep.c:1.119 src/sys/arch/amd64/amd64/netbsd32_machdep.c:1.120 --- src/sys/arch/amd64/amd64/netbsd32_machdep.c:1.119 Fri Mar 1 11:06:55 2019 +++ src/sys/arch/amd64/amd64/netbsd32_machdep.c Sun Mar 24 15:58:32 2019 @@ -1,4 +1,4 @@ -/* $NetBSD: netbsd32_machdep.c,v 1.119 2019/03/01 11:06:55 pgoyette Exp $ */ +/* $NetBSD: netbsd32_machdep.c,v 1.120 2019/03/24 15:58:32 maxv Exp $ */ /* * Copyright (c) 2001 Wasabi Systems, Inc. @@ -36,7 +36,7 @@ */ #include <sys/cdefs.h> -__KERNEL_RCSID(0, "$NetBSD: netbsd32_machdep.c,v 1.119 2019/03/01 11:06:55 pgoyette Exp $"); +__KERNEL_RCSID(0, "$NetBSD: netbsd32_machdep.c,v 1.120 2019/03/24 15:58:32 maxv Exp $"); #ifdef _KERNEL_OPT #include "opt_compat_netbsd.h" @@ -138,21 +138,22 @@ netbsd32_setregs(struct lwp *l, struct e netbsd32_adjust_limits(p); - l->l_md.md_flags = MDL_COMPAT32; /* Force iret not sysret */ - pcb->pcb_flags = PCB_COMPAT32; - fpu_save_area_clear(l, pack->ep_osversion >= 699002600 ? __NetBSD_NPXCW__ : __NetBSD_COMPAT_NPXCW__); - x86_dbregs_clear(l); + kpreempt_disable(); + pcb->pcb_flags = PCB_COMPAT32; p->p_flag |= PK_32; + l->l_md.md_flags = MDL_COMPAT32; /* force iret not sysret */ + cpu_segregs32_zero(l); + cpu_fsgs_reload(l, LSEL(LUDATA32_SEL, SEL_UPL), + LSEL(LUDATA32_SEL, SEL_UPL)); + kpreempt_enable(); tf = l->l_md.md_regs; tf->tf_ds = LSEL(LUDATA32_SEL, SEL_UPL); tf->tf_es = LSEL(LUDATA32_SEL, SEL_UPL); - cpu_segregs32_zero(l); - cpu_fsgs_reload(l, tf->tf_ds, tf->tf_es); tf->tf_rdi = 0; tf->tf_rsi = 0; tf->tf_rbp = 0; Index: src/sys/compat/linux32/arch/amd64/linux32_machdep.c diff -u src/sys/compat/linux32/arch/amd64/linux32_machdep.c:1.43 src/sys/compat/linux32/arch/amd64/linux32_machdep.c:1.44 --- src/sys/compat/linux32/arch/amd64/linux32_machdep.c:1.43 Sat Oct 21 07:24:26 2017 +++ src/sys/compat/linux32/arch/amd64/linux32_machdep.c Sun Mar 24 15:58:32 2019 @@ -1,4 +1,4 @@ -/* $NetBSD: linux32_machdep.c,v 1.43 2017/10/21 07:24:26 maxv Exp $ */ +/* $NetBSD: linux32_machdep.c,v 1.44 2019/03/24 15:58:32 maxv Exp $ */ /*- * Copyright (c) 2006 Emmanuel Dreyfus, all rights reserved. @@ -31,7 +31,7 @@ * POSSIBILITY OF SUCH DAMAGE. */ #include <sys/cdefs.h> -__KERNEL_RCSID(0, "$NetBSD: linux32_machdep.c,v 1.43 2017/10/21 07:24:26 maxv Exp $"); +__KERNEL_RCSID(0, "$NetBSD: linux32_machdep.c,v 1.44 2019/03/24 15:58:32 maxv Exp $"); #if defined(_KERNEL_OPT) #include "opt_user_ldt.h" @@ -287,10 +287,14 @@ linux32_setregs(struct lwp *l, struct ex fpu_save_area_clear(l, __Linux_NPXCW__); - l->l_md.md_flags = MDL_COMPAT32; /* Forces iret not sysret */ + kpreempt_disable(); pcb->pcb_flags = PCB_COMPAT32; - p->p_flag |= PK_32; + l->l_md.md_flags = MDL_COMPAT32; /* force iret not sysret */ + cpu_segregs32_zero(l); + cpu_fsgs_reload(l, GSEL(GUDATA32_SEL, SEL_UPL), + GSEL(GUDATA32_SEL, SEL_UPL)); + kpreempt_enable(); tf = l->l_md.md_regs; tf->tf_rax = 0; @@ -315,8 +319,6 @@ linux32_setregs(struct lwp *l, struct ex tf->tf_ss = GSEL(GUDATA32_SEL, SEL_UPL); tf->tf_ds = GSEL(GUDATA32_SEL, SEL_UPL); tf->tf_es = GSEL(GUDATA32_SEL, SEL_UPL); - cpu_segregs32_zero(l); - cpu_fsgs_reload(l, GSEL(GUDATA32_SEL, SEL_UPL), GSEL(GUDATA32_SEL, SEL_UPL)); } static void