From 64c3431808bdab2ccef97d7a444018c416b080b5 Mon Sep 17 00:00:00 2001 From: Sven Schnelle Date: Wed, 13 Mar 2024 09:51:22 +0100 Subject: [PATCH] s390/entry: compare gmap asce to determine guest/host fault With the current implementation, there are some cornercases where a host fault would be treated as a guest fault, for example when the sie instruction causes a program check. Therefore store the gmap asce in ptregs, and use that to compare the primary asce from the fault instead of matching instruction addresses. Suggested-by: Heiko Carstens Signed-off-by: Sven Schnelle Signed-off-by: Heiko Carstens --- arch/s390/include/asm/ptrace.h | 2 -- arch/s390/kernel/entry.S | 31 +++++++++++++++---------------- arch/s390/mm/fault.c | 4 +++- 3 files changed, 18 insertions(+), 19 deletions(-) diff --git a/arch/s390/include/asm/ptrace.h b/arch/s390/include/asm/ptrace.h index 788bc4467445..2ad9324f6338 100644 --- a/arch/s390/include/asm/ptrace.h +++ b/arch/s390/include/asm/ptrace.h @@ -14,13 +14,11 @@ #define PIF_SYSCALL 0 /* inside a system call */ #define PIF_EXECVE_PGSTE_RESTART 1 /* restart execve for PGSTE binaries */ #define PIF_SYSCALL_RET_SET 2 /* return value was set via ptrace */ -#define PIF_GUEST_FAULT 3 /* indicates program check in sie64a */ #define PIF_FTRACE_FULL_REGS 4 /* all register contents valid (ftrace) */ #define _PIF_SYSCALL BIT(PIF_SYSCALL) #define _PIF_EXECVE_PGSTE_RESTART BIT(PIF_EXECVE_PGSTE_RESTART) #define _PIF_SYSCALL_RET_SET BIT(PIF_SYSCALL_RET_SET) -#define _PIF_GUEST_FAULT BIT(PIF_GUEST_FAULT) #define _PIF_FTRACE_FULL_REGS BIT(PIF_FTRACE_FULL_REGS) #define PSW32_MASK_PER _AC(0x40000000, UL) diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index a0543db0bcae..787394978bc0 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -119,8 +119,8 @@ _LPP_OFFSET = __LC_LPP .endm #if IS_ENABLED(CONFIG_KVM) - .macro SIEEXIT - lg %r9,__SF_SIE_CONTROL(%r15) # get control block pointer + .macro SIEEXIT sie_control + lg %r9,\sie_control # get control block pointer ni __SIE_PROG0C+3(%r9),0xfe # no longer in SIE lctlg %c1,%c1,__LC_KERNEL_ASCE # load primary asce ni __LC_CPU_FLAGS+7,255-_CIF_SIE @@ -316,21 +316,13 @@ SYM_CODE_START(pgm_check_handler) stpt __LC_SYS_ENTER_TIMER BPOFF stmg %r8,%r15,__LC_SAVE_AREA_SYNC - lghi %r10,0 + lgr %r10,%r15 lmg %r8,%r9,__LC_PGM_OLD_PSW tmhh %r8,0x0001 # coming from user space? jno .Lpgm_skip_asce lctlg %c1,%c1,__LC_KERNEL_ASCE j 3f # -> fault in user space .Lpgm_skip_asce: -#if IS_ENABLED(CONFIG_KVM) - # cleanup critical section for program checks in __sie64a - TSTMSK __LC_CPU_FLAGS,_CIF_SIE - jz 1f - BPENTER __SF_SIE_FLAGS(%r15),_TIF_ISOLATE_BP_GUEST - SIEEXIT - lghi %r10,_PIF_GUEST_FAULT -#endif 1: tmhh %r8,0x4000 # PER bit set in old PSW ? jnz 2f # -> enabled, can't be a double fault tm __LC_PGM_ILC+3,0x80 # check for per exception @@ -341,13 +333,20 @@ SYM_CODE_START(pgm_check_handler) CHECK_VMAP_STACK __LC_SAVE_AREA_SYNC,4f 3: lg %r15,__LC_KERNEL_STACK 4: la %r11,STACK_FRAME_OVERHEAD(%r15) - stg %r10,__PT_FLAGS(%r11) + xc __PT_FLAGS(8,%r11),__PT_FLAGS(%r11) xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15) stmg %r0,%r7,__PT_R0(%r11) mvc __PT_R8(64,%r11),__LC_SAVE_AREA_SYNC mvc __PT_LAST_BREAK(8,%r11),__LC_PGM_LAST_BREAK - stmg %r8,%r9,__PT_PSW(%r11) - + stctg %c1,%c1,__PT_CR1(%r11) +#if IS_ENABLED(CONFIG_KVM) + lg %r12,__LC_GMAP + clc __GMAP_ASCE(8,%r12), __PT_CR1(%r11) + jne 5f + BPENTER __SF_SIE_FLAGS(%r10),_TIF_ISOLATE_BP_GUEST + SIEEXIT __SF_SIE_CONTROL(%r10) +#endif +5: stmg %r8,%r9,__PT_PSW(%r11) # clear user controlled registers to prevent speculative use xgr %r0,%r0 xgr %r1,%r1 @@ -399,7 +398,7 @@ SYM_CODE_START(\name) TSTMSK __LC_CPU_FLAGS,_CIF_SIE jz 0f BPENTER __SF_SIE_FLAGS(%r15),_TIF_ISOLATE_BP_GUEST - SIEEXIT + SIEEXIT __SF_SIE_CONTROL(%r15) #endif 0: CHECK_STACK __LC_SAVE_AREA_ASYNC aghi %r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE) @@ -507,7 +506,7 @@ SYM_CODE_START(mcck_int_handler) clgrjhe %r9,%r14, 4f oi __LC_CPU_FLAGS+7, _CIF_MCCK_GUEST 4: BPENTER __SF_SIE_FLAGS(%r15),_TIF_ISOLATE_BP_GUEST - SIEEXIT + SIEEXIT __SF_SIE_CONTROL(%r15) #endif .Lmcck_user: lg %r15,__LC_MCCK_STACK diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c index ac4c78546d97..c421dd44ffbe 100644 --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -67,13 +67,15 @@ early_initcall(fault_init); static enum fault_type get_fault_type(struct pt_regs *regs) { union teid teid = { .val = regs->int_parm_long }; + struct gmap *gmap; if (likely(teid.as == PSW_BITS_AS_PRIMARY)) { if (user_mode(regs)) return USER_FAULT; if (!IS_ENABLED(CONFIG_PGSTE)) return KERNEL_FAULT; - if (test_pt_regs_flag(regs, PIF_GUEST_FAULT)) + gmap = (struct gmap *)S390_lowcore.gmap; + if (regs->cr1 == gmap->asce) return GMAP_FAULT; return KERNEL_FAULT; }