tjh.dev / kernel
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powerpc/pseries: Export hardware trace macro dump via debugfs

This patch adds debugfs interface to export Hardware Trace Macro (HTM)
function data in a LPAR. New hypervisor call "H_HTM" has been
defined to setup, configure, control and dump the HTM data.
This patch supports only dumping of HTM data in a LPAR.
New debugfs folder called "htmdump" has been added under
/sys/kernel/debug/arch path which contains files need to
pass required parameters for the H_HTM dump function. New Kconfig
option called "CONFIG_HTMDUMP" is added in platform/pseries
for the same.

With this module loaded, list of files in debugfs path

/sys/kernel/debug/powerpc/htmdump
coreindexonchip htmtype nodalchipindex nodeindex trace

Signed-off-by: Abhishek Dubey <adubey@linux.ibm.com>
Co-developed-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Reviewed-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250113164039.302017-2-adubey@linux.ibm.com

authored by

Abhishek Dubey and committed by
Madhavan Srinivasan 81c3d637 708220ae

+131
+9
arch/powerpc/platforms/pseries/Kconfig
··· 128 128 will be reused for other LPARs. The interface allows firmware to 129 129 balance memory across many LPARs. 130 130 131 + config HTMDUMP 132 + tristate "PowerVM data dumper" 133 + depends on PPC_PSERIES && DEBUG_FS 134 + default m 135 + help 136 + Select this option, if you want to enable the kernel debugfs 137 + interface to dump the Hardware Trace Macro (HTM) function data 138 + in the LPAR. 139 + 131 140 config HV_PERF_CTRS 132 141 bool "Hypervisor supplied PMU events (24x7 & GPCI)" 133 142 default y
+1
arch/powerpc/platforms/pseries/Makefile
··· 19 19 obj-$(CONFIG_HVCS) += hvcserver.o 20 20 obj-$(CONFIG_HCALL_STATS) += hvCall_inst.o 21 21 obj-$(CONFIG_CMM) += cmm.o 22 + obj-$(CONFIG_HTMDUMP) += htmdump.o 22 23 obj-$(CONFIG_IO_EVENT_IRQ) += io_event_irq.o 23 24 obj-$(CONFIG_LPARCFG) += lparcfg.o 24 25 obj-$(CONFIG_IBMVIO) += vio.o
+121
arch/powerpc/platforms/pseries/htmdump.c
··· 1 + // SPDX-License-Identifier: GPL-2.0-or-later 2 + /* 3 + * Copyright (C) IBM Corporation, 2024 4 + */ 5 + 6 + #define pr_fmt(fmt) "htmdump: " fmt 7 + 8 + #include <linux/debugfs.h> 9 + #include <linux/module.h> 10 + #include <asm/io.h> 11 + #include <asm/machdep.h> 12 + #include <asm/plpar_wrappers.h> 13 + 14 + static void *htm_buf; 15 + static u32 nodeindex; 16 + static u32 nodalchipindex; 17 + static u32 coreindexonchip; 18 + static u32 htmtype; 19 + static struct dentry *htmdump_debugfs_dir; 20 + 21 + static ssize_t htmdump_read(struct file *filp, char __user *ubuf, 22 + size_t count, loff_t *ppos) 23 + { 24 + void *htm_buf = filp->private_data; 25 + unsigned long page, read_size, available; 26 + loff_t offset; 27 + long rc; 28 + 29 + page = ALIGN_DOWN(*ppos, PAGE_SIZE); 30 + offset = (*ppos) % PAGE_SIZE; 31 + 32 + rc = htm_get_dump_hardware(nodeindex, nodalchipindex, coreindexonchip, 33 + htmtype, virt_to_phys(htm_buf), PAGE_SIZE, page); 34 + 35 + switch (rc) { 36 + case H_SUCCESS: 37 + /* H_PARTIAL for the case where all available data can't be 38 + * returned due to buffer size constraint. 39 + */ 40 + case H_PARTIAL: 41 + break; 42 + /* H_NOT_AVAILABLE indicates reading from an offset outside the range, 43 + * i.e. past end of file. 44 + */ 45 + case H_NOT_AVAILABLE: 46 + return 0; 47 + case H_BUSY: 48 + case H_LONG_BUSY_ORDER_1_MSEC: 49 + case H_LONG_BUSY_ORDER_10_MSEC: 50 + case H_LONG_BUSY_ORDER_100_MSEC: 51 + case H_LONG_BUSY_ORDER_1_SEC: 52 + case H_LONG_BUSY_ORDER_10_SEC: 53 + case H_LONG_BUSY_ORDER_100_SEC: 54 + return -EBUSY; 55 + case H_PARAMETER: 56 + case H_P2: 57 + case H_P3: 58 + case H_P4: 59 + case H_P5: 60 + case H_P6: 61 + return -EINVAL; 62 + case H_STATE: 63 + return -EIO; 64 + case H_AUTHORITY: 65 + return -EPERM; 66 + } 67 + 68 + available = PAGE_SIZE; 69 + read_size = min(count, available); 70 + *ppos += read_size; 71 + return simple_read_from_buffer(ubuf, count, &offset, htm_buf, available); 72 + } 73 + 74 + static const struct file_operations htmdump_fops = { 75 + .llseek = NULL, 76 + .read = htmdump_read, 77 + .open = simple_open, 78 + }; 79 + 80 + static int htmdump_init_debugfs(void) 81 + { 82 + htm_buf = kmalloc(PAGE_SIZE, GFP_KERNEL); 83 + if (!htm_buf) { 84 + pr_err("Failed to allocate htmdump buf\n"); 85 + return -ENOMEM; 86 + } 87 + 88 + htmdump_debugfs_dir = debugfs_create_dir("htmdump", 89 + arch_debugfs_dir); 90 + 91 + debugfs_create_u32("nodeindex", 0600, 92 + htmdump_debugfs_dir, &nodeindex); 93 + debugfs_create_u32("nodalchipindex", 0600, 94 + htmdump_debugfs_dir, &nodalchipindex); 95 + debugfs_create_u32("coreindexonchip", 0600, 96 + htmdump_debugfs_dir, &coreindexonchip); 97 + debugfs_create_u32("htmtype", 0600, 98 + htmdump_debugfs_dir, &htmtype); 99 + debugfs_create_file("trace", 0400, htmdump_debugfs_dir, htm_buf, &htmdump_fops); 100 + 101 + return 0; 102 + } 103 + 104 + static int __init htmdump_init(void) 105 + { 106 + if (htmdump_init_debugfs()) 107 + return -ENOMEM; 108 + 109 + return 0; 110 + } 111 + 112 + static void __exit htmdump_exit(void) 113 + { 114 + debugfs_remove_recursive(htmdump_debugfs_dir); 115 + kfree(htm_buf); 116 + } 117 + 118 + module_init(htmdump_init); 119 + module_exit(htmdump_exit); 120 + MODULE_DESCRIPTION("PHYP Hardware Trace Macro (HTM) data dumper"); 121 + MODULE_LICENSE("GPL");