From cbfe74a753e877b49dc54e9b04d5d42230ca0aed Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Fri, 8 Jan 2016 12:29:10 +0530 Subject: ARCv2: STAR 9000950267: Handle return from intr to Delay Slot #2 Returning to delay slot, riding an interrupti, had one loose end. AUX_USER_SP used for restoring user mode SP upon RTIE was not being setup from orig task's saved value, causing task to use wrong SP, leading to ProtV errors. The reason being: - INTERRUPT_EPILOGUE returns to a kernel trampoline, thus not expected to restore it - EXCEPTION_EPILOGUE is not used at all Fix that by restoring AUX_USER_SP explicitly in the trampoline. This was broken in the original workaround, but the error scenarios got reduced considerably since v3.14 due to following: 1. The Linuxthreads.old based userspace at the time caused many more exceptions in delay slot than the current NPTL based one. Infact with current userspace the error doesn't happen at all. 2. Return from interrupt (delay slot or otherwise) doesn't get exercised much after commit 4de0e52867d8 ("Really Re-enable interrupts to avoid deadlocks") since IRQ_ACTIVE.active being clear means most returns are as if from pure kernel (even for active interrupts) Infact the issue only happened in an experimental branch where I was tinkering with reverted 4de0e52867d8 Cc: stable@kernel.org # v4.2+ Fixes: 4255b07f2c9c ("ARCv2: STAR 9000793984: Handle return from intr to Delay Slot") Signed-off-by: Vineet Gupta --- arch/arc/kernel/entry-arcv2.S | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) (limited to 'arch/arc/kernel') diff --git a/arch/arc/kernel/entry-arcv2.S b/arch/arc/kernel/entry-arcv2.S index cbfec79..b178302 100644 --- a/arch/arc/kernel/entry-arcv2.S +++ b/arch/arc/kernel/entry-arcv2.S @@ -211,7 +211,11 @@ debug_marker_syscall: ; (since IRQ NOT allowed in DS in ARCv2, this can only happen if orig ; entry was via Exception in DS which got preempted in kernel). ; -; IRQ RTIE won't reliably restore DE bit and/or BTA, needs handling +; IRQ RTIE won't reliably restore DE bit and/or BTA, needs workaround +; +; Solution is return from Intr w/o any delay slot quirks into a kernel trampoline +; and from pure kernel mode return to delay slot which handles DS bit/BTA correctly + .Lintr_ret_to_delay_slot: debug_marker_ds: @@ -222,18 +226,23 @@ debug_marker_ds: ld r2, [sp, PT_ret] ld r3, [sp, PT_status32] + ; STAT32 for Int return created from scratch + ; (No delay dlot, disable Further intr in trampoline) + bic r0, r3, STATUS_U_MASK|STATUS_DE_MASK|STATUS_IE_MASK|STATUS_L_MASK st r0, [sp, PT_status32] mov r1, .Lintr_ret_to_delay_slot_2 st r1, [sp, PT_ret] + ; Orig exception PC/STAT32 safekept @orig_r0 and @event stack slots st r2, [sp, 0] st r3, [sp, 4] b .Lisr_ret_fast_path .Lintr_ret_to_delay_slot_2: + ; Trampoline to restore orig exception PC/STAT32/BTA/AUX_USER_SP sub sp, sp, SZ_PT_REGS st r9, [sp, -4] @@ -243,11 +252,19 @@ debug_marker_ds: ld r9, [sp, 4] sr r9, [erstatus] + ; restore AUX_USER_SP if returning to U mode + bbit0 r9, STATUS_U_BIT, 1f + ld r9, [sp, PT_sp] + sr r9, [AUX_USER_SP] + +1: ld r9, [sp, 8] sr r9, [erbta] ld r9, [sp, -4] add sp, sp, SZ_PT_REGS + + ; return from pure kernel mode to delay slot rtie END(ret_from_exception) -- cgit v1.1 From d584f0fb041d86b9605fae1f0ed9e268f217daa9 Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Fri, 22 Jan 2016 14:27:50 +0530 Subject: ARCv2: clocksource: Rename GRTC -> GFRC ... ... it is now called Global Free Running Counter Signed-off-by: Vineet Gupta --- arch/arc/kernel/mcip.c | 10 +++++----- arch/arc/kernel/time.c | 8 ++++---- 2 files changed, 9 insertions(+), 9 deletions(-) (limited to 'arch/arc/kernel') diff --git a/arch/arc/kernel/mcip.c b/arch/arc/kernel/mcip.c index bd237ac..bc771f5 100644 --- a/arch/arc/kernel/mcip.c +++ b/arch/arc/kernel/mcip.c @@ -96,13 +96,13 @@ static void mcip_probe_n_setup(void) #ifdef CONFIG_CPU_BIG_ENDIAN unsigned int pad3:8, idu:1, llm:1, num_cores:6, - iocoh:1, grtc:1, dbg:1, pad2:1, + iocoh:1, gfrc:1, dbg:1, pad2:1, msg:1, sem:1, ipi:1, pad:1, ver:8; #else unsigned int ver:8, pad:1, ipi:1, sem:1, msg:1, - pad2:1, dbg:1, grtc:1, iocoh:1, + pad2:1, dbg:1, gfrc:1, iocoh:1, num_cores:6, llm:1, idu:1, pad3:8; #endif @@ -116,7 +116,7 @@ static void mcip_probe_n_setup(void) IS_AVAIL1(mp.ipi, "IPI "), IS_AVAIL1(mp.idu, "IDU "), IS_AVAIL1(mp.dbg, "DEBUG "), - IS_AVAIL1(mp.grtc, "GRTC")); + IS_AVAIL1(mp.gfrc, "GFRC")); idu_detected = mp.idu; @@ -125,8 +125,8 @@ static void mcip_probe_n_setup(void) __mcip_cmd_data(CMD_DEBUG_SET_MASK, 0xf, 0xf); } - if (IS_ENABLED(CONFIG_ARC_HAS_GRTC) && !mp.grtc) - panic("kernel trying to use non-existent GRTC\n"); + if (IS_ENABLED(CONFIG_ARC_HAS_GFRC) && !mp.gfrc) + panic("kernel trying to use non-existent GFRC\n"); } struct plat_smp_ops plat_smp_ops = { diff --git a/arch/arc/kernel/time.c b/arch/arc/kernel/time.c index dfad287..156d983 100644 --- a/arch/arc/kernel/time.c +++ b/arch/arc/kernel/time.c @@ -62,7 +62,7 @@ /********** Clock Source Device *********/ -#ifdef CONFIG_ARC_HAS_GRTC +#ifdef CONFIG_ARC_HAS_GFRC static int arc_counter_setup(void) { @@ -83,10 +83,10 @@ static cycle_t arc_counter_read(struct clocksource *cs) local_irq_save(flags); - __mcip_cmd(CMD_GRTC_READ_LO, 0); + __mcip_cmd(CMD_GFRC_READ_LO, 0); stamp.l = read_aux_reg(ARC_REG_MCIP_READBACK); - __mcip_cmd(CMD_GRTC_READ_HI, 0); + __mcip_cmd(CMD_GFRC_READ_HI, 0); stamp.h = read_aux_reg(ARC_REG_MCIP_READBACK); local_irq_restore(flags); @@ -95,7 +95,7 @@ static cycle_t arc_counter_read(struct clocksource *cs) } static struct clocksource arc_counter = { - .name = "ARConnect GRTC", + .name = "ARConnect GFRC", .rating = 400, .read = arc_counter_read, .mask = CLOCKSOURCE_MASK(64), -- cgit v1.1 From b89bd1f4fbaecaa842588a034f8a44f4a84597e4 Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Fri, 22 Jan 2016 15:20:18 +0530 Subject: ARC: shrink cpuinfo by not saving full timer BCR Signed-off-by: Vineet Gupta --- arch/arc/kernel/setup.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) (limited to 'arch/arc/kernel') diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c index e1b8744..7f0a3cb 100644 --- a/arch/arc/kernel/setup.c +++ b/arch/arc/kernel/setup.c @@ -45,6 +45,7 @@ struct cpuinfo_arc cpuinfo_arc700[NR_CPUS]; static void read_arc_build_cfg_regs(void) { struct bcr_perip uncached_space; + struct bcr_timer timer; struct bcr_generic bcr; struct cpuinfo_arc *cpu = &cpuinfo_arc700[smp_processor_id()]; unsigned long perip_space; @@ -53,7 +54,11 @@ static void read_arc_build_cfg_regs(void) READ_BCR(AUX_IDENTITY, cpu->core); READ_BCR(ARC_REG_ISA_CFG_BCR, cpu->isa); - READ_BCR(ARC_REG_TIMERS_BCR, cpu->timers); + READ_BCR(ARC_REG_TIMERS_BCR, timer); + cpu->extn.timer0 = timer.t0; + cpu->extn.timer1 = timer.t1; + cpu->extn.rtc = timer.rtc; + cpu->vec_base = read_aux_reg(AUX_INTR_VEC_BASE); READ_BCR(ARC_REG_D_UNCACH_BCR, uncached_space); @@ -208,9 +213,9 @@ static char *arc_cpu_mumbojumbo(int cpu_id, char *buf, int len) (unsigned int)(arc_get_core_freq() / 10000) % 100); n += scnprintf(buf + n, len - n, "Timers\t\t: %s%s%s%s\nISA Extn\t: ", - IS_AVAIL1(cpu->timers.t0, "Timer0 "), - IS_AVAIL1(cpu->timers.t1, "Timer1 "), - IS_AVAIL2(cpu->timers.rtc, "64-bit RTC ", + IS_AVAIL1(cpu->extn.timer0, "Timer0 "), + IS_AVAIL1(cpu->extn.timer1, "Timer1 "), + IS_AVAIL2(cpu->extn.rtc, "Local-64-bit-Ctr ", CONFIG_ARC_HAS_RTC)); n += i = scnprintf(buf + n, len - n, "%s%s%s%s%s", @@ -293,13 +298,13 @@ static void arc_chk_core_config(void) struct cpuinfo_arc *cpu = &cpuinfo_arc700[smp_processor_id()]; int fpu_enabled; - if (!cpu->timers.t0) + if (!cpu->extn.timer0) panic("Timer0 is not present!\n"); - if (!cpu->timers.t1) + if (!cpu->extn.timer1) panic("Timer1 is not present!\n"); - if (IS_ENABLED(CONFIG_ARC_HAS_RTC) && !cpu->timers.rtc) + if (IS_ENABLED(CONFIG_ARC_HAS_RTC) && !cpu->extn.rtc) panic("RTC is not present\n"); #ifdef CONFIG_ARC_HAS_DCCM -- cgit v1.1 From 4d0cb15fccd1db9dac0c964b2ccf10874e69f5b8 Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Fri, 29 Jan 2016 16:47:44 +0530 Subject: ARCv2: Check for LL-SC livelock only if LLSC is enabled Signed-off-by: Vineet Gupta --- arch/arc/kernel/setup.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/arc/kernel') diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c index 7f0a3cb..a7edceb 100644 --- a/arch/arc/kernel/setup.c +++ b/arch/arc/kernel/setup.c @@ -339,6 +339,7 @@ static void arc_chk_core_config(void) panic("FPU non-existent, disable CONFIG_ARC_FPU_SAVE_RESTORE\n"); if (is_isa_arcv2() && IS_ENABLED(CONFIG_SMP) && cpu->isa.atomic && + IS_ENABLED(CONFIG_ARC_HAS_LLSC) && !IS_ENABLED(CONFIG_ARC_STAR_9000923308)) panic("llock/scond livelock workaround missing\n"); } -- cgit v1.1 From dec2b2849cfccf09822d6ce3f9bc84b8c8611152 Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Sun, 7 Feb 2016 12:54:35 +0530 Subject: ARCv2: intc: Allow interruption by lowest priority interrupt ARC HS Cores support configurable multiple interrupt priorities of upto 16 levels. There is processor "interrupt preemption threshhold" in STATUS32.E[4:1] And several places need to set this up: 1. seed value as kernel is booting 2. seed value for user space programs 3. Arg to SLEEP instruction in idle task (what interrupt prio can wake) 4. Per-IRQ line prioirty (i.e. what is the priority of interrupt raised by a peripheral or timer or perf counter... Currently above sites use the highest priority 0. This can be potential problem when multiple priorities are supported. e.g. user space could only be interrupted by P0 interrupt, not others... So turn this over and instead make default interruption level to be the lowest priority possible 15. This should be fine even if there are fewer priority levels configured (say two: P0 HIGH, P1 LOW) This feature also effectively disables FIRQ feature if present in hardware config. With old code, a P0 interrupt would be FIRQ, needing special handling (ISR or Register Banks) which is NOT supported yet. Now it not be P0 (P15 or whatever is lowest prio) so FIRQ is not triggered. Signed-off-by: Vineet Gupta --- arch/arc/kernel/intc-arcv2.c | 41 ++++++++++++++++++++++++----------------- 1 file changed, 24 insertions(+), 17 deletions(-) (limited to 'arch/arc/kernel') diff --git a/arch/arc/kernel/intc-arcv2.c b/arch/arc/kernel/intc-arcv2.c index 0394f9f..9425263 100644 --- a/arch/arc/kernel/intc-arcv2.c +++ b/arch/arc/kernel/intc-arcv2.c @@ -14,6 +14,8 @@ #include #include +static int irq_prio; + /* * Early Hardware specific Interrupt setup * -Called very early (start_kernel -> setup_arch -> setup_processor) @@ -24,6 +26,14 @@ void arc_init_IRQ(void) { unsigned int tmp; + struct irq_build { +#ifdef CONFIG_CPU_BIG_ENDIAN + unsigned int pad:3, firq:1, prio:4, exts:8, irqs:8, ver:8; +#else + unsigned int ver:8, irqs:8, exts:8, prio:4, firq:1, pad:3; +#endif + } irq_bcr; + struct aux_irq_ctrl { #ifdef CONFIG_CPU_BIG_ENDIAN unsigned int res3:18, save_idx_regs:1, res2:1, @@ -46,28 +56,25 @@ void arc_init_IRQ(void) WRITE_AUX(AUX_IRQ_CTRL, ictrl); - /* setup status32, don't enable intr yet as kernel doesn't want */ - tmp = read_aux_reg(0xa); - tmp |= ISA_INIT_STATUS_BITS; - tmp &= ~STATUS_IE_MASK; - asm volatile("flag %0 \n"::"r"(tmp)); - /* * ARCv2 core intc provides multiple interrupt priorities (upto 16). * Typical builds though have only two levels (0-high, 1-low) * Linux by default uses lower prio 1 for most irqs, reserving 0 for * NMI style interrupts in future (say perf) - * - * Read the intc BCR to confirm that Linux default priority is avail - * in h/w - * - * Note: - * IRQ_BCR[27..24] contains N-1 (for N priority levels) and prio level - * is 0 based. */ - tmp = (read_aux_reg(ARC_REG_IRQ_BCR) >> 24 ) & 0xF; - if (ARCV2_IRQ_DEF_PRIO > tmp) - panic("Linux default irq prio incorrect\n"); + + READ_BCR(ARC_REG_IRQ_BCR, irq_bcr); + + irq_prio = irq_bcr.prio; /* Encoded as N-1 for N levels */ + pr_info("archs-intc\t: %d priority levels (default %d)%s\n", + irq_prio + 1, irq_prio, + irq_bcr.firq ? " FIRQ (not used)":""); + + /* setup status32, don't enable intr yet as kernel doesn't want */ + tmp = read_aux_reg(0xa); + tmp |= STATUS_AD_MASK | (irq_prio << 1); + tmp &= ~STATUS_IE_MASK; + asm volatile("flag %0 \n"::"r"(tmp)); } static void arcv2_irq_mask(struct irq_data *data) @@ -86,7 +93,7 @@ void arcv2_irq_enable(struct irq_data *data) { /* set default priority */ write_aux_reg(AUX_IRQ_SELECT, data->irq); - write_aux_reg(AUX_IRQ_PRIORITY, ARCV2_IRQ_DEF_PRIO); + write_aux_reg(AUX_IRQ_PRIORITY, irq_prio); /* * hw auto enables (linux unmask) all by default -- cgit v1.1