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![Nathan Chancellor](/assets/img/avatar_default.png)
After commit 7cbd631d4dec ("cpuidle: pseries: Fixup CEDE0 latency only
for POWER10 onwards"), pseries_idle_probe() is no longer inlined when
compiling with clang, which causes a modpost warning:
WARNING: modpost: vmlinux.o(.text+0xc86a54): Section mismatch in
reference from the function pseries_idle_probe() to the function
.init.text:fixup_cede0_latency()
The function pseries_idle_probe() references
the function __init fixup_cede0_latency().
This is often because pseries_idle_probe lacks a __init
annotation or the annotation of fixup_cede0_latency is wrong.
pseries_idle_probe() is a non-init function, which calls
fixup_cede0_latency(), which is an init function, explaining the
mismatch. pseries_idle_probe() is only called from
pseries_processor_idle_init(), which is an init function, so mark
pseries_idle_probe() as __init so there is no more warning.
Fixes: 054e44ba99
("cpuidle: pseries: Add function to parse extended CEDE records")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210803211547.1093820-1-nathan@kernel.org
479 lines
12 KiB
C
479 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* cpuidle-pseries - idle state cpuidle driver.
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* Adapted from drivers/idle/intel_idle.c and
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* drivers/acpi/processor_idle.c
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*
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/moduleparam.h>
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#include <linux/cpuidle.h>
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#include <linux/cpu.h>
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#include <linux/notifier.h>
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#include <asm/paca.h>
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#include <asm/reg.h>
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#include <asm/machdep.h>
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#include <asm/firmware.h>
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#include <asm/runlatch.h>
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#include <asm/idle.h>
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#include <asm/plpar_wrappers.h>
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#include <asm/rtas.h>
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static struct cpuidle_driver pseries_idle_driver = {
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.name = "pseries_idle",
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.owner = THIS_MODULE,
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};
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static int max_idle_state __read_mostly;
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static struct cpuidle_state *cpuidle_state_table __read_mostly;
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static u64 snooze_timeout __read_mostly;
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static bool snooze_timeout_en __read_mostly;
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static int snooze_loop(struct cpuidle_device *dev,
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struct cpuidle_driver *drv,
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int index)
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{
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u64 snooze_exit_time;
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set_thread_flag(TIF_POLLING_NRFLAG);
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pseries_idle_prolog();
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local_irq_enable();
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snooze_exit_time = get_tb() + snooze_timeout;
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while (!need_resched()) {
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HMT_low();
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HMT_very_low();
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if (likely(snooze_timeout_en) && get_tb() > snooze_exit_time) {
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/*
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* Task has not woken up but we are exiting the polling
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* loop anyway. Require a barrier after polling is
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* cleared to order subsequent test of need_resched().
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*/
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clear_thread_flag(TIF_POLLING_NRFLAG);
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smp_mb();
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break;
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}
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}
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HMT_medium();
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clear_thread_flag(TIF_POLLING_NRFLAG);
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local_irq_disable();
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pseries_idle_epilog();
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return index;
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}
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static void check_and_cede_processor(void)
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{
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/*
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* Ensure our interrupt state is properly tracked,
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* also checks if no interrupt has occurred while we
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* were soft-disabled
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*/
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if (prep_irq_for_idle()) {
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cede_processor();
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#ifdef CONFIG_TRACE_IRQFLAGS
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/* Ensure that H_CEDE returns with IRQs on */
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if (WARN_ON(!(mfmsr() & MSR_EE)))
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__hard_irq_enable();
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#endif
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}
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}
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/*
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* XCEDE: Extended CEDE states discovered through the
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* "ibm,get-systems-parameter" RTAS call with the token
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* CEDE_LATENCY_TOKEN
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*/
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/*
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* Section 7.3.16 System Parameters Option of PAPR version 2.8.1 has a
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* table with all the parameters to ibm,get-system-parameters.
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* CEDE_LATENCY_TOKEN corresponds to the token value for Cede Latency
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* Settings Information.
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*/
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#define CEDE_LATENCY_TOKEN 45
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/*
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* If the platform supports the cede latency settings information system
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* parameter it must provide the following information in the NULL terminated
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* parameter string:
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*
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* a. The first byte is the length “N” of each cede latency setting record minus
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* one (zero indicates a length of 1 byte).
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*
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* b. For each supported cede latency setting a cede latency setting record
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* consisting of the first “N” bytes as per the following table.
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*
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* -----------------------------
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* | Field | Field |
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* | Name | Length |
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* -----------------------------
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* | Cede Latency | 1 Byte |
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* | Specifier Value | |
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* -----------------------------
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* | Maximum wakeup | |
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* | latency in | 8 Bytes |
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* | tb-ticks | |
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* -----------------------------
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* | Responsive to | |
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* | external | 1 Byte |
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* | interrupts | |
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* -----------------------------
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*
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* This version has cede latency record size = 10.
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*
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* The structure xcede_latency_payload represents a) and b) with
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* xcede_latency_record representing the table in b).
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*
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* xcede_latency_parameter is what gets returned by
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* ibm,get-systems-parameter RTAS call when made with
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* CEDE_LATENCY_TOKEN.
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*
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* These structures are only used to represent the data obtained by the RTAS
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* call. The data is in big-endian.
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*/
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struct xcede_latency_record {
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u8 hint;
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__be64 latency_ticks;
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u8 wake_on_irqs;
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} __packed;
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// Make space for 16 records, which "should be enough".
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struct xcede_latency_payload {
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u8 record_size;
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struct xcede_latency_record records[16];
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} __packed;
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struct xcede_latency_parameter {
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__be16 payload_size;
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struct xcede_latency_payload payload;
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u8 null_char;
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} __packed;
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static unsigned int nr_xcede_records;
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static struct xcede_latency_parameter xcede_latency_parameter __initdata;
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static int __init parse_cede_parameters(void)
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{
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struct xcede_latency_payload *payload;
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u32 total_xcede_records_size;
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u8 xcede_record_size;
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u16 payload_size;
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int ret, i;
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ret = rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1,
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NULL, CEDE_LATENCY_TOKEN, __pa(&xcede_latency_parameter),
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sizeof(xcede_latency_parameter));
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if (ret) {
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pr_err("xcede: Error parsing CEDE_LATENCY_TOKEN\n");
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return ret;
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}
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payload_size = be16_to_cpu(xcede_latency_parameter.payload_size);
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payload = &xcede_latency_parameter.payload;
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xcede_record_size = payload->record_size + 1;
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if (xcede_record_size != sizeof(struct xcede_latency_record)) {
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pr_err("xcede: Expected record-size %lu. Observed size %u.\n",
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sizeof(struct xcede_latency_record), xcede_record_size);
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return -EINVAL;
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}
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pr_info("xcede: xcede_record_size = %d\n", xcede_record_size);
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/*
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* Since the payload_size includes the last NULL byte and the
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* xcede_record_size, the remaining bytes correspond to array of all
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* cede_latency settings.
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*/
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total_xcede_records_size = payload_size - 2;
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nr_xcede_records = total_xcede_records_size / xcede_record_size;
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for (i = 0; i < nr_xcede_records; i++) {
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struct xcede_latency_record *record = &payload->records[i];
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u64 latency_ticks = be64_to_cpu(record->latency_ticks);
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u8 wake_on_irqs = record->wake_on_irqs;
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u8 hint = record->hint;
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pr_info("xcede: Record %d : hint = %u, latency = 0x%llx tb ticks, Wake-on-irq = %u\n",
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i, hint, latency_ticks, wake_on_irqs);
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}
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return 0;
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}
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#define NR_DEDICATED_STATES 2 /* snooze, CEDE */
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static u8 cede_latency_hint[NR_DEDICATED_STATES];
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static int dedicated_cede_loop(struct cpuidle_device *dev,
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struct cpuidle_driver *drv,
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int index)
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{
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u8 old_latency_hint;
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pseries_idle_prolog();
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get_lppaca()->donate_dedicated_cpu = 1;
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old_latency_hint = get_lppaca()->cede_latency_hint;
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get_lppaca()->cede_latency_hint = cede_latency_hint[index];
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HMT_medium();
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check_and_cede_processor();
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local_irq_disable();
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get_lppaca()->donate_dedicated_cpu = 0;
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get_lppaca()->cede_latency_hint = old_latency_hint;
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pseries_idle_epilog();
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return index;
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}
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static int shared_cede_loop(struct cpuidle_device *dev,
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struct cpuidle_driver *drv,
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int index)
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{
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pseries_idle_prolog();
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/*
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* Yield the processor to the hypervisor. We return if
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* an external interrupt occurs (which are driven prior
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* to returning here) or if a prod occurs from another
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* processor. When returning here, external interrupts
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* are enabled.
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*/
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check_and_cede_processor();
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local_irq_disable();
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pseries_idle_epilog();
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return index;
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}
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/*
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* States for dedicated partition case.
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*/
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static struct cpuidle_state dedicated_states[NR_DEDICATED_STATES] = {
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{ /* Snooze */
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.name = "snooze",
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.desc = "snooze",
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.exit_latency = 0,
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.target_residency = 0,
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.enter = &snooze_loop },
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{ /* CEDE */
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.name = "CEDE",
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.desc = "CEDE",
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.exit_latency = 10,
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.target_residency = 100,
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.enter = &dedicated_cede_loop },
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};
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/*
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* States for shared partition case.
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*/
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static struct cpuidle_state shared_states[] = {
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{ /* Snooze */
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.name = "snooze",
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.desc = "snooze",
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.exit_latency = 0,
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.target_residency = 0,
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.enter = &snooze_loop },
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{ /* Shared Cede */
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.name = "Shared Cede",
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.desc = "Shared Cede",
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.exit_latency = 10,
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.target_residency = 100,
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.enter = &shared_cede_loop },
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};
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static int pseries_cpuidle_cpu_online(unsigned int cpu)
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{
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struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
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if (dev && cpuidle_get_driver()) {
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cpuidle_pause_and_lock();
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cpuidle_enable_device(dev);
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cpuidle_resume_and_unlock();
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}
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return 0;
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}
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static int pseries_cpuidle_cpu_dead(unsigned int cpu)
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{
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struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
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if (dev && cpuidle_get_driver()) {
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cpuidle_pause_and_lock();
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cpuidle_disable_device(dev);
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cpuidle_resume_and_unlock();
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}
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return 0;
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}
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/*
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* pseries_cpuidle_driver_init()
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*/
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static int pseries_cpuidle_driver_init(void)
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{
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int idle_state;
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struct cpuidle_driver *drv = &pseries_idle_driver;
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drv->state_count = 0;
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for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
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/* Is the state not enabled? */
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if (cpuidle_state_table[idle_state].enter == NULL)
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continue;
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drv->states[drv->state_count] = /* structure copy */
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cpuidle_state_table[idle_state];
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drv->state_count += 1;
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}
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return 0;
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}
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static void __init fixup_cede0_latency(void)
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{
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struct xcede_latency_payload *payload;
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u64 min_xcede_latency_us = UINT_MAX;
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int i;
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if (parse_cede_parameters())
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return;
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pr_info("cpuidle: Skipping the %d Extended CEDE idle states\n",
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nr_xcede_records);
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payload = &xcede_latency_parameter.payload;
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/*
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* The CEDE idle state maps to CEDE(0). While the hypervisor
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* does not advertise CEDE(0) exit latency values, it does
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* advertise the latency values of the extended CEDE states.
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* We use the lowest advertised exit latency value as a proxy
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* for the exit latency of CEDE(0).
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*/
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for (i = 0; i < nr_xcede_records; i++) {
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struct xcede_latency_record *record = &payload->records[i];
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u8 hint = record->hint;
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u64 latency_tb = be64_to_cpu(record->latency_ticks);
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u64 latency_us = DIV_ROUND_UP_ULL(tb_to_ns(latency_tb), NSEC_PER_USEC);
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/*
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* We expect the exit latency of an extended CEDE
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* state to be non-zero, it to since it takes at least
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* a few nanoseconds to wakeup the idle CPU and
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* dispatch the virtual processor into the Linux
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* Guest.
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*
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* So we consider only non-zero value for performing
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* the fixup of CEDE(0) latency.
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*/
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if (latency_us == 0) {
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pr_warn("cpuidle: Skipping xcede record %d [hint=%d]. Exit latency = 0us\n",
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i, hint);
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continue;
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}
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if (latency_us < min_xcede_latency_us)
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min_xcede_latency_us = latency_us;
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}
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if (min_xcede_latency_us != UINT_MAX) {
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dedicated_states[1].exit_latency = min_xcede_latency_us;
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dedicated_states[1].target_residency = 10 * (min_xcede_latency_us);
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pr_info("cpuidle: Fixed up CEDE exit latency to %llu us\n",
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min_xcede_latency_us);
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}
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}
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/*
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* pseries_idle_probe()
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* Choose state table for shared versus dedicated partition
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*/
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static int __init pseries_idle_probe(void)
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{
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if (cpuidle_disable != IDLE_NO_OVERRIDE)
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return -ENODEV;
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if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
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/*
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* Use local_paca instead of get_lppaca() since
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* preemption is not disabled, and it is not required in
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* fact, since lppaca_ptr does not need to be the value
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* associated to the current CPU, it can be from any CPU.
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*/
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if (lppaca_shared_proc(local_paca->lppaca_ptr)) {
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cpuidle_state_table = shared_states;
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max_idle_state = ARRAY_SIZE(shared_states);
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} else {
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/*
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* Use firmware provided latency values
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* starting with POWER10 platforms. In the
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* case that we are running on a POWER10
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* platform but in an earlier compat mode, we
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* can still use the firmware provided values.
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*
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* However, on platforms prior to POWER10, we
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* cannot rely on the accuracy of the firmware
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* provided latency values. On such platforms,
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* go with the conservative default estimate
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* of 10us.
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*/
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if (cpu_has_feature(CPU_FTR_ARCH_31) || pvr_version_is(PVR_POWER10))
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fixup_cede0_latency();
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cpuidle_state_table = dedicated_states;
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max_idle_state = NR_DEDICATED_STATES;
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}
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} else
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return -ENODEV;
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if (max_idle_state > 1) {
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snooze_timeout_en = true;
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snooze_timeout = cpuidle_state_table[1].target_residency *
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tb_ticks_per_usec;
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}
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return 0;
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}
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static int __init pseries_processor_idle_init(void)
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{
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int retval;
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retval = pseries_idle_probe();
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if (retval)
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return retval;
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pseries_cpuidle_driver_init();
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retval = cpuidle_register(&pseries_idle_driver, NULL);
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if (retval) {
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printk(KERN_DEBUG "Registration of pseries driver failed.\n");
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return retval;
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}
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retval = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
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"cpuidle/pseries:online",
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pseries_cpuidle_cpu_online, NULL);
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WARN_ON(retval < 0);
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retval = cpuhp_setup_state_nocalls(CPUHP_CPUIDLE_DEAD,
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"cpuidle/pseries:DEAD", NULL,
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pseries_cpuidle_cpu_dead);
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WARN_ON(retval < 0);
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printk(KERN_DEBUG "pseries_idle_driver registered\n");
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return 0;
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}
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device_initcall(pseries_processor_idle_init);
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