diff options
Diffstat (limited to 'arch/s390/kernel')
-rw-r--r-- | arch/s390/kernel/Makefile | 4 | ||||
-rw-r--r-- | arch/s390/kernel/entry.S | 113 | ||||
-rw-r--r-- | arch/s390/kernel/module.c | 62 | ||||
-rw-r--r-- | arch/s390/kernel/nospec-branch.c | 100 | ||||
-rw-r--r-- | arch/s390/kernel/setup.c | 4 | ||||
-rw-r--r-- | arch/s390/kernel/smp.c | 1 | ||||
-rw-r--r-- | arch/s390/kernel/vmlinux.lds.S | 14 |
7 files changed, 264 insertions, 34 deletions
diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile index 909bce6..7f27e3d 100644 --- a/arch/s390/kernel/Makefile +++ b/arch/s390/kernel/Makefile @@ -29,6 +29,7 @@ UBSAN_SANITIZE_early.o := n # ifneq ($(CC_FLAGS_MARCH),-march=z900) CFLAGS_REMOVE_als.o += $(CC_FLAGS_MARCH) +CFLAGS_REMOVE_als.o += $(CC_FLAGS_EXPOLINE) CFLAGS_als.o += -march=z900 AFLAGS_REMOVE_head.o += $(CC_FLAGS_MARCH) AFLAGS_head.o += -march=z900 @@ -63,6 +64,9 @@ obj-y += entry.o reipl.o relocate_kernel.o kdebugfs.o alternative.o extra-y += head.o head64.o vmlinux.lds +obj-$(CONFIG_EXPOLINE) += nospec-branch.o +CFLAGS_REMOVE_expoline.o += $(CC_FLAGS_EXPOLINE) + obj-$(CONFIG_MODULES) += module.o obj-$(CONFIG_SMP) += smp.o obj-$(CONFIG_SCHED_TOPOLOGY) += topology.o diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 53145b5..13a133a 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -222,6 +222,68 @@ _PIF_WORK = (_PIF_PER_TRAP | _PIF_SYSCALL_RESTART) .popsection .endm +#ifdef CONFIG_EXPOLINE + + .macro GEN_BR_THUNK name,reg,tmp + .section .text.\name,"axG",@progbits,\name,comdat + .globl \name + .hidden \name + .type \name,@function +\name: + .cfi_startproc +#ifdef CONFIG_HAVE_MARCH_Z10_FEATURES + exrl 0,0f +#else + larl \tmp,0f + ex 0,0(\tmp) +#endif + j . +0: br \reg + .cfi_endproc + .endm + + GEN_BR_THUNK __s390x_indirect_jump_r1use_r9,%r9,%r1 + GEN_BR_THUNK __s390x_indirect_jump_r1use_r14,%r14,%r1 + GEN_BR_THUNK __s390x_indirect_jump_r11use_r14,%r14,%r11 + + .macro BASR_R14_R9 +0: brasl %r14,__s390x_indirect_jump_r1use_r9 + .pushsection .s390_indirect_branches,"a",@progbits + .long 0b-. + .popsection + .endm + + .macro BR_R1USE_R14 +0: jg __s390x_indirect_jump_r1use_r14 + .pushsection .s390_indirect_branches,"a",@progbits + .long 0b-. + .popsection + .endm + + .macro BR_R11USE_R14 +0: jg __s390x_indirect_jump_r11use_r14 + .pushsection .s390_indirect_branches,"a",@progbits + .long 0b-. + .popsection + .endm + +#else /* CONFIG_EXPOLINE */ + + .macro BASR_R14_R9 + basr %r14,%r9 + .endm + + .macro BR_R1USE_R14 + br %r14 + .endm + + .macro BR_R11USE_R14 + br %r14 + .endm + +#endif /* CONFIG_EXPOLINE */ + + .section .kprobes.text, "ax" .Ldummy: /* @@ -237,7 +299,7 @@ _PIF_WORK = (_PIF_PER_TRAP | _PIF_SYSCALL_RESTART) ENTRY(__bpon) .globl __bpon BPON - br %r14 + BR_R1USE_R14 /* * Scheduler resume function, called by switch_to @@ -261,9 +323,9 @@ ENTRY(__switch_to) mvc __LC_CURRENT_PID(4,%r0),0(%r3) # store pid of next lmg %r6,%r15,__SF_GPRS(%r15) # load gprs of next task TSTMSK __LC_MACHINE_FLAGS,MACHINE_FLAG_LPP - bzr %r14 + jz 0f .insn s,0xb2800000,__LC_LPP # set program parameter - br %r14 +0: BR_R1USE_R14 .L__critical_start: @@ -330,7 +392,7 @@ sie_exit: xgr %r5,%r5 lmg %r6,%r14,__SF_GPRS(%r15) # restore kernel registers lg %r2,__SF_EMPTY+16(%r15) # return exit reason code - br %r14 + BR_R1USE_R14 .Lsie_fault: lghi %r14,-EFAULT stg %r14,__SF_EMPTY+16(%r15) # set exit reason code @@ -389,7 +451,7 @@ ENTRY(system_call) lgf %r9,0(%r8,%r10) # get system call add. TSTMSK __TI_flags(%r12),_TIF_TRACE jnz .Lsysc_tracesys - basr %r14,%r9 # call sys_xxxx + BASR_R14_R9 # call sys_xxxx stg %r2,__PT_R2(%r11) # store return value .Lsysc_return: @@ -574,7 +636,7 @@ ENTRY(system_call) lmg %r3,%r7,__PT_R3(%r11) stg %r7,STACK_FRAME_OVERHEAD(%r15) lg %r2,__PT_ORIG_GPR2(%r11) - basr %r14,%r9 # call sys_xxx + BASR_R14_R9 # call sys_xxx stg %r2,__PT_R2(%r11) # store return value .Lsysc_tracenogo: TSTMSK __TI_flags(%r12),_TIF_TRACE @@ -598,7 +660,7 @@ ENTRY(ret_from_fork) lmg %r9,%r10,__PT_R9(%r11) # load gprs ENTRY(kernel_thread_starter) la %r2,0(%r10) - basr %r14,%r9 + BASR_R14_R9 j .Lsysc_tracenogo /* @@ -678,9 +740,9 @@ ENTRY(pgm_check_handler) nill %r10,0x007f sll %r10,2 je .Lpgm_return - lgf %r1,0(%r10,%r1) # load address of handler routine + lgf %r9,0(%r10,%r1) # load address of handler routine lgr %r2,%r11 # pass pointer to pt_regs - basr %r14,%r1 # branch to interrupt-handler + BASR_R14_R9 # branch to interrupt-handler .Lpgm_return: LOCKDEP_SYS_EXIT tm __PT_PSW+1(%r11),0x01 # returning to user ? @@ -998,7 +1060,7 @@ ENTRY(psw_idle) stpt __TIMER_IDLE_ENTER(%r2) .Lpsw_idle_lpsw: lpswe __SF_EMPTY(%r15) - br %r14 + BR_R1USE_R14 .Lpsw_idle_end: /* @@ -1012,7 +1074,7 @@ ENTRY(save_fpu_regs) lg %r2,__LC_CURRENT aghi %r2,__TASK_thread TSTMSK __LC_CPU_FLAGS,_CIF_FPU - bor %r14 + jo .Lsave_fpu_regs_exit stfpc __THREAD_FPU_fpc(%r2) lg %r3,__THREAD_FPU_regs(%r2) TSTMSK __LC_MACHINE_FLAGS,MACHINE_FLAG_VX @@ -1039,7 +1101,8 @@ ENTRY(save_fpu_regs) std 15,120(%r3) .Lsave_fpu_regs_done: oi __LC_CPU_FLAGS+7,_CIF_FPU - br %r14 +.Lsave_fpu_regs_exit: + BR_R1USE_R14 .Lsave_fpu_regs_end: EXPORT_SYMBOL(save_fpu_regs) @@ -1057,7 +1120,7 @@ load_fpu_regs: lg %r4,__LC_CURRENT aghi %r4,__TASK_thread TSTMSK __LC_CPU_FLAGS,_CIF_FPU - bnor %r14 + jno .Lload_fpu_regs_exit lfpc __THREAD_FPU_fpc(%r4) TSTMSK __LC_MACHINE_FLAGS,MACHINE_FLAG_VX lg %r4,__THREAD_FPU_regs(%r4) # %r4 <- reg save area @@ -1084,7 +1147,8 @@ load_fpu_regs: ld 15,120(%r4) .Lload_fpu_regs_done: ni __LC_CPU_FLAGS+7,255-_CIF_FPU - br %r14 +.Lload_fpu_regs_exit: + BR_R1USE_R14 .Lload_fpu_regs_end: .L__critical_end: @@ -1301,7 +1365,7 @@ cleanup_critical: jl 0f clg %r9,BASED(.Lcleanup_table+104) # .Lload_fpu_regs_end jl .Lcleanup_load_fpu_regs -0: br %r14 +0: BR_R11USE_R14 .align 8 .Lcleanup_table: @@ -1337,7 +1401,7 @@ cleanup_critical: ni __SIE_PROG0C+3(%r9),0xfe # no longer in SIE lctlg %c1,%c1,__LC_USER_ASCE # load primary asce larl %r9,sie_exit # skip forward to sie_exit - br %r14 + BR_R11USE_R14 #endif .Lcleanup_system_call: @@ -1390,7 +1454,7 @@ cleanup_critical: stg %r15,56(%r11) # r15 stack pointer # set new psw address and exit larl %r9,.Lsysc_do_svc - br %r14 + BR_R11USE_R14 .Lcleanup_system_call_insn: .quad system_call .quad .Lsysc_stmg @@ -1402,7 +1466,7 @@ cleanup_critical: .Lcleanup_sysc_tif: larl %r9,.Lsysc_tif - br %r14 + BR_R11USE_R14 .Lcleanup_sysc_restore: # check if stpt has been executed @@ -1419,14 +1483,14 @@ cleanup_critical: mvc 0(64,%r11),__PT_R8(%r9) lmg %r0,%r7,__PT_R0(%r9) 1: lmg %r8,%r9,__LC_RETURN_PSW - br %r14 + BR_R11USE_R14 .Lcleanup_sysc_restore_insn: .quad .Lsysc_exit_timer .quad .Lsysc_done - 4 .Lcleanup_io_tif: larl %r9,.Lio_tif - br %r14 + BR_R11USE_R14 .Lcleanup_io_restore: # check if stpt has been executed @@ -1440,7 +1504,7 @@ cleanup_critical: mvc 0(64,%r11),__PT_R8(%r9) lmg %r0,%r7,__PT_R0(%r9) 1: lmg %r8,%r9,__LC_RETURN_PSW - br %r14 + BR_R11USE_R14 .Lcleanup_io_restore_insn: .quad .Lio_exit_timer .quad .Lio_done - 4 @@ -1493,17 +1557,17 @@ cleanup_critical: # prepare return psw nihh %r8,0xfcfd # clear irq & wait state bits lg %r9,48(%r11) # return from psw_idle - br %r14 + BR_R11USE_R14 .Lcleanup_idle_insn: .quad .Lpsw_idle_lpsw .Lcleanup_save_fpu_regs: larl %r9,save_fpu_regs - br %r14 + BR_R11USE_R14 .Lcleanup_load_fpu_regs: larl %r9,load_fpu_regs - br %r14 + BR_R11USE_R14 /* * Integer constants @@ -1523,7 +1587,6 @@ cleanup_critical: .Lsie_crit_mcck_length: .quad .Lsie_skip - .Lsie_entry #endif - .section .rodata, "a" #define SYSCALL(esame,emu) .long esame .globl sys_call_table diff --git a/arch/s390/kernel/module.c b/arch/s390/kernel/module.c index b7abfad..1fc6d1f 100644 --- a/arch/s390/kernel/module.c +++ b/arch/s390/kernel/module.c @@ -19,6 +19,8 @@ #include <linux/moduleloader.h> #include <linux/bug.h> #include <asm/alternative.h> +#include <asm/nospec-branch.h> +#include <asm/facility.h> #if 0 #define DEBUGP printk @@ -156,7 +158,11 @@ int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, me->arch.got_offset = me->core_layout.size; me->core_layout.size += me->arch.got_size; me->arch.plt_offset = me->core_layout.size; - me->core_layout.size += me->arch.plt_size; + if (me->arch.plt_size) { + if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_call_disable) + me->arch.plt_size += PLT_ENTRY_SIZE; + me->core_layout.size += me->arch.plt_size; + } return 0; } @@ -310,9 +316,21 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, unsigned int *ip; ip = me->core_layout.base + me->arch.plt_offset + info->plt_offset; - ip[0] = 0x0d10e310; /* basr 1,0; lg 1,10(1); br 1 */ - ip[1] = 0x100a0004; - ip[2] = 0x07f10000; + ip[0] = 0x0d10e310; /* basr 1,0 */ + ip[1] = 0x100a0004; /* lg 1,10(1) */ + if (IS_ENABLED(CONFIG_EXPOLINE) && + !nospec_call_disable) { + unsigned int *ij; + ij = me->core_layout.base + + me->arch.plt_offset + + me->arch.plt_size - PLT_ENTRY_SIZE; + ip[2] = 0xa7f40000 + /* j __jump_r1 */ + (unsigned int)(u16) + (((unsigned long) ij - 8 - + (unsigned long) ip) / 2); + } else { + ip[2] = 0x07f10000; /* br %r1 */ + } ip[3] = (unsigned int) (val >> 32); ip[4] = (unsigned int) val; info->plt_initialized = 1; @@ -418,16 +436,42 @@ int module_finalize(const Elf_Ehdr *hdr, struct module *me) { const Elf_Shdr *s; - char *secstrings; + char *secstrings, *secname; + void *aseg; + + if (IS_ENABLED(CONFIG_EXPOLINE) && + !nospec_call_disable && me->arch.plt_size) { + unsigned int *ij; + + ij = me->core_layout.base + me->arch.plt_offset + + me->arch.plt_size - PLT_ENTRY_SIZE; + if (test_facility(35)) { + ij[0] = 0xc6000000; /* exrl %r0,.+10 */ + ij[1] = 0x0005a7f4; /* j . */ + ij[2] = 0x000007f1; /* br %r1 */ + } else { + ij[0] = 0x44000000 | (unsigned int) + offsetof(struct lowcore, br_r1_trampoline); + ij[1] = 0xa7f40000; /* j . */ + } + } secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) { - if (!strcmp(".altinstructions", secstrings + s->sh_name)) { - /* patch .altinstructions */ - void *aseg = (void *)s->sh_addr; + aseg = (void *) s->sh_addr; + secname = secstrings + s->sh_name; + if (!strcmp(".altinstructions", secname)) + /* patch .altinstructions */ apply_alternatives(aseg, aseg + s->sh_size); - } + + if (IS_ENABLED(CONFIG_EXPOLINE) && + (!strcmp(".nospec_call_table", secname))) + nospec_call_revert(aseg, aseg + s->sh_size); + + if (IS_ENABLED(CONFIG_EXPOLINE) && + (!strcmp(".nospec_return_table", secname))) + nospec_return_revert(aseg, aseg + s->sh_size); } jump_label_apply_nops(me); diff --git a/arch/s390/kernel/nospec-branch.c b/arch/s390/kernel/nospec-branch.c new file mode 100644 index 0000000..69d7fcf --- /dev/null +++ b/arch/s390/kernel/nospec-branch.c @@ -0,0 +1,100 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/module.h> +#include <asm/nospec-branch.h> + +int nospec_call_disable = IS_ENABLED(EXPOLINE_OFF); +int nospec_return_disable = !IS_ENABLED(EXPOLINE_FULL); + +static int __init nospectre_v2_setup_early(char *str) +{ + nospec_call_disable = 1; + nospec_return_disable = 1; + return 0; +} +early_param("nospectre_v2", nospectre_v2_setup_early); + +static int __init spectre_v2_setup_early(char *str) +{ + if (str && !strncmp(str, "on", 2)) { + nospec_call_disable = 0; + nospec_return_disable = 0; + } + if (str && !strncmp(str, "off", 3)) { + nospec_call_disable = 1; + nospec_return_disable = 1; + } + if (str && !strncmp(str, "auto", 4)) { + nospec_call_disable = 0; + nospec_return_disable = 1; + } + return 0; +} +early_param("spectre_v2", spectre_v2_setup_early); + +static void __init_or_module __nospec_revert(s32 *start, s32 *end) +{ + enum { BRCL_EXPOLINE, BRASL_EXPOLINE } type; + u8 *instr, *thunk, *br; + u8 insnbuf[6]; + s32 *epo; + + /* Second part of the instruction replace is always a nop */ + memcpy(insnbuf + 2, (char[]) { 0x47, 0x00, 0x00, 0x00 }, 4); + for (epo = start; epo < end; epo++) { + instr = (u8 *) epo + *epo; + if (instr[0] == 0xc0 && (instr[1] & 0x0f) == 0x04) + type = BRCL_EXPOLINE; /* brcl instruction */ + else if (instr[0] == 0xc0 && (instr[1] & 0x0f) == 0x05) + type = BRASL_EXPOLINE; /* brasl instruction */ + else + continue; + thunk = instr + (*(int *)(instr + 2)) * 2; + if (thunk[0] == 0xc6 && thunk[1] == 0x00) + /* exrl %r0,<target-br> */ + br = thunk + (*(int *)(thunk + 2)) * 2; + else if (thunk[0] == 0xc0 && (thunk[1] & 0x0f) == 0x00 && + thunk[6] == 0x44 && thunk[7] == 0x00 && + (thunk[8] & 0x0f) == 0x00 && thunk[9] == 0x00 && + (thunk[1] & 0xf0) == (thunk[8] & 0xf0)) + /* larl %rx,<target br> + ex %r0,0(%rx) */ + br = thunk + (*(int *)(thunk + 2)) * 2; + else + continue; + if (br[0] != 0x07 || (br[1] & 0xf0) != 0xf0) + continue; + switch (type) { + case BRCL_EXPOLINE: + /* brcl to thunk, replace with br + nop */ + insnbuf[0] = br[0]; + insnbuf[1] = (instr[1] & 0xf0) | (br[1] & 0x0f); + break; + case BRASL_EXPOLINE: + /* brasl to thunk, replace with basr + nop */ + insnbuf[0] = 0x0d; + insnbuf[1] = (instr[1] & 0xf0) | (br[1] & 0x0f); + break; + } + + s390_kernel_write(instr, insnbuf, 6); + } +} + +void __init_or_module nospec_call_revert(s32 *start, s32 *end) +{ + if (nospec_call_disable) + __nospec_revert(start, end); +} + +void __init_or_module nospec_return_revert(s32 *start, s32 *end) +{ + if (nospec_return_disable) + __nospec_revert(start, end); +} + +extern s32 __nospec_call_start[], __nospec_call_end[]; +extern s32 __nospec_return_start[], __nospec_return_end[]; +void __init nospec_init_branches(void) +{ + nospec_call_revert(__nospec_call_start, __nospec_call_end); + nospec_return_revert(__nospec_return_start, __nospec_return_end); +} diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c index bcd2a4a..a6a91f0 100644 --- a/arch/s390/kernel/setup.c +++ b/arch/s390/kernel/setup.c @@ -68,6 +68,7 @@ #include <asm/sysinfo.h> #include <asm/numa.h> #include <asm/alternative.h> +#include <asm/nospec-branch.h> #include "entry.h" /* @@ -379,6 +380,7 @@ static void __init setup_lowcore(void) lc->spinlock_index = 0; arch_spin_lock_setup(0); #endif + lc->br_r1_trampoline = 0x07f1; /* br %r1 */ set_prefix((u32)(unsigned long) lc); lowcore_ptr[0] = lc; @@ -954,6 +956,8 @@ void __init setup_arch(char **cmdline_p) set_preferred_console(); apply_alternative_instructions(); + if (IS_ENABLED(CONFIG_EXPOLINE)) + nospec_init_branches(); /* Setup zfcpdump support */ setup_zfcpdump(); diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index 2fd7d60..a4a9fe1 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -214,6 +214,7 @@ static int pcpu_alloc_lowcore(struct pcpu *pcpu, int cpu) lc->cpu_nr = cpu; lc->spinlock_lockval = arch_spin_lockval(cpu); lc->spinlock_index = 0; + lc->br_r1_trampoline = 0x07f1; /* br %r1 */ if (nmi_alloc_per_cpu(lc)) goto out; if (vdso_alloc_per_cpu(lc)) diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S index 608cf29..08d12cf 100644 --- a/arch/s390/kernel/vmlinux.lds.S +++ b/arch/s390/kernel/vmlinux.lds.S @@ -123,6 +123,20 @@ SECTIONS *(.altinstr_replacement) } + /* + * Table with the patch locations to undo expolines + */ + .nospec_call_table : { + __nospec_call_start = . ; + *(.s390_indirect*) + __nospec_call_end = . ; + } + .nospec_return_table : { + __nospec_return_start = . ; + *(.s390_return*) + __nospec_return_end = . ; + } + /* early.c uses stsi, which requires page aligned data. */ . = ALIGN(PAGE_SIZE); INIT_DATA_SECTION(0x100) |