From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AB8JxZrcaGgDqM2FWkd64J8PtOv9HT78g3qYnQiHjLXoy4RwVpzYN5LhjLlJdqDFM2fTTlQm6K9p ARC-Seal: i=1; a=rsa-sha256; t=1524837654; cv=none; d=google.com; s=arc-20160816; b=anj4j56Y2WkmTmZXABPpwr5nvG/mHiAW2xmk5NDepCS7mpsuuosnTaLZ+Go7ctLZzS MbQ0y3TsfXrIqoSYUjxBGHki0CnKCFa828hkSciWOJxBRq5tv9ME5RkzoMsmAzRijetP XK7B7sex41JPJ76zHHfljZ1x2ky85aAR9vVJoDzXW0lB5YBVVPKVLfxuyhZiM9C+0Fhl pOr6gIO8GDIE1wdgbf/m0gX68L7TxGFEqwKafl1TvBfaPpeGy+VjDUBFq8OsMmCG1YLk PcgY9Q8bdeBN5Y496jUis5IFV7ez5QsL+MiE5ane4YF2OFfHSPUroaZQKDvPtUDBiJK8 MgNg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:dmarc-filter:arc-authentication-results; bh=4D0Stab0ngP+szBQZryreRWxnCIcG1UD25uO1oaDuHo=; b=YOvNZcQ3reIber6c9Q0fimtbm0l0+9A3IIn4BKRqjTxHBRI7DyWZD4J4HAXXL3kFVY vGzc8v68Qn2nK/BgfmXmvrikc/J8P7sR6YsBImumR3ffJ4znuMIN7d2gc+k7hujR651B dwbLYt6K/KhgAsm+kQXM0Q7tGZ2U1YfRejHuZ/7Mcx6eu/LjdQ7eM/FdBrueEf7ob2ut PD69ljK7uw/29SydFYP3Ko4FHw9g0H1vi5mBbiRGEr3IY9pShXXrBt5clAhNGobBrZ86 VQVFfm4VS/92v8PzjZlsKdScRDidOc3vK1gesOTc7dpjseq3qp1qusDVAMNAgcYp3r2y YVxA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of srs0=4/0d=hq=linuxfoundation.org=gregkh@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=SRS0=4/0d=HQ=linuxfoundation.org=gregkh@kernel.org Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of srs0=4/0d=hq=linuxfoundation.org=gregkh@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=SRS0=4/0d=HQ=linuxfoundation.org=gregkh@kernel.org DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2A2E22189F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=fail smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Martin Schwidefsky , Cornelia Huck Subject: [PATCH 4.4 16/50] s390: add options to change branch prediction behaviour for the kernel Date: Fri, 27 Apr 2018 15:58:18 +0200 Message-Id: <20180427135656.701217280@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180427135655.623669681@linuxfoundation.org> References: <20180427135655.623669681@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1598908168299324374?= X-GMAIL-MSGID: =?utf-8?q?1598908168299324374?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Martin Schwidefsky [ Upstream commit d768bd892fc8f066cd3aa000eb1867bcf32db0ee ] Add the PPA instruction to the system entry and exit path to switch the kernel to a different branch prediction behaviour. The instructions are added via CPU alternatives and can be disabled with the "nospec" or the "nobp=0" kernel parameter. If the default behaviour selected with CONFIG_KERNEL_NOBP is set to "n" then the "nobp=1" parameter can be used to enable the changed kernel branch prediction. Acked-by: Cornelia Huck Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman --- arch/s390/Kconfig | 17 +++++++++++++ arch/s390/include/asm/processor.h | 1 arch/s390/kernel/alternative.c | 23 ++++++++++++++++++ arch/s390/kernel/early.c | 2 + arch/s390/kernel/entry.S | 48 ++++++++++++++++++++++++++++++++++++++ arch/s390/kernel/ipl.c | 1 arch/s390/kernel/smp.c | 2 + 7 files changed, 94 insertions(+) --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -705,6 +705,23 @@ config SECCOMP If unsure, say Y. +config KERNEL_NOBP + def_bool n + prompt "Enable modified branch prediction for the kernel by default" + help + If this option is selected the kernel will switch to a modified + branch prediction mode if the firmware interface is available. + The modified branch prediction mode improves the behaviour in + regard to speculative execution. + + With the option enabled the kernel parameter "nobp=0" or "nospec" + can be used to run the kernel in the normal branch prediction mode. + + With the option disabled the modified branch prediction mode is + enabled with the "nobp=1" kernel parameter. + + If unsure, say N. + endmenu menu "Power Management" --- a/arch/s390/include/asm/processor.h +++ b/arch/s390/include/asm/processor.h @@ -69,6 +69,7 @@ extern void s390_adjust_jiffies(void); extern const struct seq_operations cpuinfo_op; extern int sysctl_ieee_emulation_warnings; extern void execve_tail(void); +extern void __bpon(void); /* * User space process size: 2GB for 31 bit, 4TB or 8PT for 64 bit. --- a/arch/s390/kernel/alternative.c +++ b/arch/s390/kernel/alternative.c @@ -14,6 +14,29 @@ static int __init disable_alternative_in early_param("noaltinstr", disable_alternative_instructions); +static int __init nobp_setup_early(char *str) +{ + bool enabled; + int rc; + + rc = kstrtobool(str, &enabled); + if (rc) + return rc; + if (enabled && test_facility(82)) + __set_facility(82, S390_lowcore.alt_stfle_fac_list); + else + __clear_facility(82, S390_lowcore.alt_stfle_fac_list); + return 0; +} +early_param("nobp", nobp_setup_early); + +static int __init nospec_setup_early(char *str) +{ + __clear_facility(82, S390_lowcore.alt_stfle_fac_list); + return 0; +} +early_param("nospec", nospec_setup_early); + struct brcl_insn { u16 opc; s32 disp; --- a/arch/s390/kernel/early.c +++ b/arch/s390/kernel/early.c @@ -282,6 +282,8 @@ static noinline __init void setup_facili memcpy(S390_lowcore.alt_stfle_fac_list, S390_lowcore.stfle_fac_list, sizeof(S390_lowcore.alt_stfle_fac_list)); + if (!IS_ENABLED(CONFIG_KERNEL_NOBP)) + __clear_facility(82, S390_lowcore.alt_stfle_fac_list); } static __init void detect_diag9c(void) --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -162,8 +162,41 @@ _PIF_WORK = (_PIF_PER_TRAP) tm off+\addr, \mask .endm + .macro BPOFF + .pushsection .altinstr_replacement, "ax" +660: .long 0xb2e8c000 + .popsection +661: .long 0x47000000 + .pushsection .altinstructions, "a" + .long 661b - . + .long 660b - . + .word 82 + .byte 4 + .byte 4 + .popsection + .endm + + .macro BPON + .pushsection .altinstr_replacement, "ax" +662: .long 0xb2e8d000 + .popsection +663: .long 0x47000000 + .pushsection .altinstructions, "a" + .long 663b - . + .long 662b - . + .word 82 + .byte 4 + .byte 4 + .popsection + .endm + .section .kprobes.text, "ax" +ENTRY(__bpon) + .globl __bpon + BPON + br %r14 + /* * Scheduler resume function, called by switch_to * gpr2 = (task_struct *) prev @@ -223,7 +256,10 @@ ENTRY(sie64a) jnz .Lsie_skip TSTMSK __LC_CPU_FLAGS,_CIF_FPU jo .Lsie_skip # exit if fp/vx regs changed + BPON sie 0(%r14) +.Lsie_exit: + BPOFF .Lsie_skip: ni __SIE_PROG0C+3(%r14),0xfe # no longer in SIE lctlg %c1,%c1,__LC_USER_ASCE # load primary asce @@ -273,6 +309,7 @@ ENTRY(system_call) stpt __LC_SYNC_ENTER_TIMER .Lsysc_stmg: stmg %r8,%r15,__LC_SAVE_AREA_SYNC + BPOFF lg %r10,__LC_LAST_BREAK lg %r12,__LC_THREAD_INFO lghi %r14,_PIF_SYSCALL @@ -319,6 +356,7 @@ ENTRY(system_call) jnz .Lsysc_work # check for work TSTMSK __LC_CPU_FLAGS,_CIF_WORK jnz .Lsysc_work + BPON .Lsysc_restore: lg %r14,__LC_VDSO_PER_CPU lmg %r0,%r10,__PT_R0(%r11) @@ -479,6 +517,7 @@ ENTRY(kernel_thread_starter) ENTRY(pgm_check_handler) stpt __LC_SYNC_ENTER_TIMER + BPOFF stmg %r8,%r15,__LC_SAVE_AREA_SYNC lg %r10,__LC_LAST_BREAK lg %r12,__LC_THREAD_INFO @@ -577,6 +616,7 @@ ENTRY(pgm_check_handler) ENTRY(io_int_handler) STCK __LC_INT_CLOCK stpt __LC_ASYNC_ENTER_TIMER + BPOFF stmg %r8,%r15,__LC_SAVE_AREA_ASYNC lg %r10,__LC_LAST_BREAK lg %r12,__LC_THREAD_INFO @@ -628,9 +668,13 @@ ENTRY(io_int_handler) lg %r14,__LC_VDSO_PER_CPU lmg %r0,%r10,__PT_R0(%r11) mvc __LC_RETURN_PSW(16),__PT_PSW(%r11) + tm __PT_PSW+1(%r11),0x01 # returning to user ? + jno .Lio_exit_kernel + BPON .Lio_exit_timer: stpt __LC_EXIT_TIMER mvc __VDSO_ECTG_BASE(16,%r14),__LC_EXIT_TIMER +.Lio_exit_kernel: lmg %r11,%r15,__PT_R11(%r11) lpswe __LC_RETURN_PSW .Lio_done: @@ -762,6 +806,7 @@ ENTRY(io_int_handler) ENTRY(ext_int_handler) STCK __LC_INT_CLOCK stpt __LC_ASYNC_ENTER_TIMER + BPOFF stmg %r8,%r15,__LC_SAVE_AREA_ASYNC lg %r10,__LC_LAST_BREAK lg %r12,__LC_THREAD_INFO @@ -810,6 +855,7 @@ ENTRY(psw_idle) .insn rsy,0xeb0000000017,%r1,5,__SF_EMPTY+16(%r15) .Lpsw_idle_stcctm: #endif + BPON STCK __CLOCK_IDLE_ENTER(%r2) stpt __TIMER_IDLE_ENTER(%r2) .Lpsw_idle_lpsw: @@ -914,6 +960,7 @@ load_fpu_regs: */ ENTRY(mcck_int_handler) STCK __LC_MCCK_CLOCK + BPOFF la %r1,4095 # revalidate r1 spt __LC_CPU_TIMER_SAVE_AREA-4095(%r1) # revalidate cpu timer lmg %r0,%r15,__LC_GPREGS_SAVE_AREA-4095(%r1)# revalidate gprs @@ -980,6 +1027,7 @@ ENTRY(mcck_int_handler) mvc __LC_RETURN_MCCK_PSW(16),__PT_PSW(%r11) # move return PSW tm __LC_RETURN_MCCK_PSW+1,0x01 # returning to user ? jno 0f + BPON stpt __LC_EXIT_TIMER mvc __VDSO_ECTG_BASE(16,%r14),__LC_EXIT_TIMER 0: lmg %r11,%r15,__PT_R11(%r11) --- a/arch/s390/kernel/ipl.c +++ b/arch/s390/kernel/ipl.c @@ -563,6 +563,7 @@ static struct kset *ipl_kset; static void __ipl_run(void *unused) { + __bpon(); diag308(DIAG308_IPL, NULL); if (MACHINE_IS_VM) __cpcmd("IPL", NULL, 0, NULL); --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -301,6 +301,7 @@ static void pcpu_delegate(struct pcpu *p mem_assign_absolute(lc->restart_fn, (unsigned long) func); mem_assign_absolute(lc->restart_data, (unsigned long) data); mem_assign_absolute(lc->restart_source, source_cpu); + __bpon(); asm volatile( "0: sigp 0,%0,%2 # sigp restart to target cpu\n" " brc 2,0b # busy, try again\n" @@ -890,6 +891,7 @@ void __cpu_die(unsigned int cpu) void __noreturn cpu_die(void) { idle_task_exit(); + __bpon(); pcpu_sigp_retry(pcpu_devices + smp_processor_id(), SIGP_STOP, 0); for (;;) ; }