From af442a1baa6d00117cc7e7377ce7e6a545268684 Mon Sep 17 00:00:00 2001 From: Nishanth Aravamudan Date: Wed, 4 May 2011 12:54:16 +0000 Subject: [PATCH] powerpc: Ensure dtl buffers do not cross 4k boundary Future releases of fimrware will enforce a requirement that DTL buffers do not cross a 4k boundary. Commit 127493d5dc73589cbe00ea5ec8357cc2a4c0d82a satisfies this requirement for CONFIG_VIRT_CPU_ACCOUNTING=y kernels, but if !CONFIG_VIRT_CPU_ACCOUNTING && CONFIG_DTL=y, the current code will fail at dtl registration time. Fix this by making the kmem cache from 127493d5dc73589cbe00ea5ec8357cc2a4c0d82a visible outside of setup.c and using the same cache in both dtl.c and setup.c. This requires a bit of reorganization to ensure ordering of the kmem cache and buffer allocations. Note: Since firmware now limits the size of the buffer, I made dtl_buf_entries read-only in debugfs. Tested with upcoming firmware with the 4 combinations of CONFIG_VIRT_CPU_ACCOUNTING and CONFIG_DTL. Signed-off-by: Nishanth Aravamudan Cc: Paul Mackerras Cc: Anton Blanchard Cc: linuxppc-dev@lists.ozlabs.org Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/include/asm/lppaca.h | 2 ++ arch/powerpc/platforms/pseries/dtl.c | 20 +++++++++-------- arch/powerpc/platforms/pseries/setup.c | 31 ++++++++++++++++++-------- 3 files changed, 35 insertions(+), 18 deletions(-) diff --git a/arch/powerpc/include/asm/lppaca.h b/arch/powerpc/include/asm/lppaca.h index a077adc0b35e..e0298d26ce5d 100644 --- a/arch/powerpc/include/asm/lppaca.h +++ b/arch/powerpc/include/asm/lppaca.h @@ -210,6 +210,8 @@ struct dtl_entry { #define DISPATCH_LOG_BYTES 4096 /* bytes per cpu */ #define N_DISPATCH_LOG (DISPATCH_LOG_BYTES / sizeof(struct dtl_entry)) +extern struct kmem_cache *dtl_cache; + /* * When CONFIG_VIRT_CPU_ACCOUNTING = y, the cpu accounting code controls * reading from the dispatch trace log. If other code wants to consume diff --git a/arch/powerpc/platforms/pseries/dtl.c b/arch/powerpc/platforms/pseries/dtl.c index c371bc06434b..e9190073bb97 100644 --- a/arch/powerpc/platforms/pseries/dtl.c +++ b/arch/powerpc/platforms/pseries/dtl.c @@ -52,10 +52,10 @@ static u8 dtl_event_mask = 0x7; /* - * Size of per-cpu log buffers. Default is just under 16 pages worth. + * Size of per-cpu log buffers. Firmware requires that the buffer does + * not cross a 4k boundary. */ -static int dtl_buf_entries = (16 * 85); - +static int dtl_buf_entries = N_DISPATCH_LOG; #ifdef CONFIG_VIRT_CPU_ACCOUNTING struct dtl_ring { @@ -151,7 +151,7 @@ static int dtl_start(struct dtl *dtl) /* Register our dtl buffer with the hypervisor. The HV expects the * buffer size to be passed in the second word of the buffer */ - ((u32 *)dtl->buf)[1] = dtl->buf_entries * sizeof(struct dtl_entry); + ((u32 *)dtl->buf)[1] = DISPATCH_LOG_BYTES; hwcpu = get_hard_smp_processor_id(dtl->cpu); addr = __pa(dtl->buf); @@ -196,13 +196,15 @@ static int dtl_enable(struct dtl *dtl) long int rc; struct dtl_entry *buf = NULL; + if (!dtl_cache) + return -ENOMEM; + /* only allow one reader */ if (dtl->buf) return -EBUSY; n_entries = dtl_buf_entries; - buf = kmalloc_node(n_entries * sizeof(struct dtl_entry), - GFP_KERNEL, cpu_to_node(dtl->cpu)); + buf = kmem_cache_alloc_node(dtl_cache, GFP_KERNEL, cpu_to_node(dtl->cpu)); if (!buf) { printk(KERN_WARNING "%s: buffer alloc failed for cpu %d\n", __func__, dtl->cpu); @@ -223,7 +225,7 @@ static int dtl_enable(struct dtl *dtl) spin_unlock(&dtl->lock); if (rc) - kfree(buf); + kmem_cache_free(dtl_cache, buf); return rc; } @@ -231,7 +233,7 @@ static void dtl_disable(struct dtl *dtl) { spin_lock(&dtl->lock); dtl_stop(dtl); - kfree(dtl->buf); + kmem_cache_free(dtl_cache, dtl->buf); dtl->buf = NULL; dtl->buf_entries = 0; spin_unlock(&dtl->lock); @@ -365,7 +367,7 @@ static int dtl_init(void) event_mask_file = debugfs_create_x8("dtl_event_mask", 0600, dtl_dir, &dtl_event_mask); - buf_entries_file = debugfs_create_u32("dtl_buf_entries", 0600, + buf_entries_file = debugfs_create_u32("dtl_buf_entries", 0400, dtl_dir, &dtl_buf_entries); if (!event_mask_file || !buf_entries_file) { diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c index 1689adccc6d7..593acceeff96 100644 --- a/arch/powerpc/platforms/pseries/setup.c +++ b/arch/powerpc/platforms/pseries/setup.c @@ -278,6 +278,8 @@ static struct notifier_block pci_dn_reconfig_nb = { .notifier_call = pci_dn_reconfig_notifier, }; +struct kmem_cache *dtl_cache; + #ifdef CONFIG_VIRT_CPU_ACCOUNTING /* * Allocate space for the dispatch trace log for all possible cpus @@ -289,18 +291,12 @@ static int alloc_dispatch_logs(void) int cpu, ret; struct paca_struct *pp; struct dtl_entry *dtl; - struct kmem_cache *dtl_cache; if (!firmware_has_feature(FW_FEATURE_SPLPAR)) return 0; - dtl_cache = kmem_cache_create("dtl", DISPATCH_LOG_BYTES, - DISPATCH_LOG_BYTES, 0, NULL); - if (!dtl_cache) { - pr_warn("Failed to create dispatch trace log buffer cache\n"); - pr_warn("Stolen time statistics will be unreliable\n"); + if (!dtl_cache) return 0; - } for_each_possible_cpu(cpu) { pp = &paca[cpu]; @@ -334,10 +330,27 @@ static int alloc_dispatch_logs(void) return 0; } - -early_initcall(alloc_dispatch_logs); +#else /* !CONFIG_VIRT_CPU_ACCOUNTING */ +static inline int alloc_dispatch_logs(void) +{ + return 0; +} #endif /* CONFIG_VIRT_CPU_ACCOUNTING */ +static int alloc_dispatch_log_kmem_cache(void) +{ + dtl_cache = kmem_cache_create("dtl", DISPATCH_LOG_BYTES, + DISPATCH_LOG_BYTES, 0, NULL); + if (!dtl_cache) { + pr_warn("Failed to create dispatch trace log buffer cache\n"); + pr_warn("Stolen time statistics will be unreliable\n"); + return 0; + } + + return alloc_dispatch_logs(); +} +early_initcall(alloc_dispatch_log_kmem_cache); + static void __init pSeries_setup_arch(void) { /* Discover PIC type and setup ppc_md accordingly */ -- 2.30.2