From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- drivers/acpi/acpica/hwtimer.c | 175 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 175 insertions(+) create mode 100644 drivers/acpi/acpica/hwtimer.c (limited to 'drivers/acpi/acpica/hwtimer.c') diff --git a/drivers/acpi/acpica/hwtimer.c b/drivers/acpi/acpica/hwtimer.c new file mode 100644 index 000000000..c08bbaa95 --- /dev/null +++ b/drivers/acpi/acpica/hwtimer.c @@ -0,0 +1,175 @@ +// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0 +/****************************************************************************** + * + * Name: hwtimer.c - ACPI Power Management Timer Interface + * + * Copyright (C) 2000 - 2026, Intel Corp. + * + *****************************************************************************/ + +#define EXPORT_ACPI_INTERFACES + +#include +#include "accommon.h" + +#define _COMPONENT ACPI_HARDWARE +ACPI_MODULE_NAME("hwtimer") + +#if (!ACPI_REDUCED_HARDWARE) /* Entire module */ +/****************************************************************************** + * + * FUNCTION: acpi_get_timer_resolution + * + * PARAMETERS: resolution - Where the resolution is returned + * + * RETURN: Status and timer resolution + * + * DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits). + * + ******************************************************************************/ +acpi_status acpi_get_timer_resolution(u32 * resolution) +{ + ACPI_FUNCTION_TRACE(acpi_get_timer_resolution); + + if (!resolution) { + return_ACPI_STATUS(AE_BAD_PARAMETER); + } + + if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) { + *resolution = 24; + } else { + *resolution = 32; + } + + return_ACPI_STATUS(AE_OK); +} + +ACPI_EXPORT_SYMBOL(acpi_get_timer_resolution) + +/****************************************************************************** + * + * FUNCTION: acpi_get_timer + * + * PARAMETERS: ticks - Where the timer value is returned + * + * RETURN: Status and current timer value (ticks) + * + * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks). + * + ******************************************************************************/ +acpi_status acpi_get_timer(u32 * ticks) +{ + acpi_status status; + u64 timer_value; + + ACPI_FUNCTION_TRACE(acpi_get_timer); + + if (!ticks) { + return_ACPI_STATUS(AE_BAD_PARAMETER); + } + + /* ACPI 5.0A: PM Timer is optional */ + + if (!acpi_gbl_FADT.xpm_timer_block.address) { + return_ACPI_STATUS(AE_SUPPORT); + } + + status = acpi_hw_read(&timer_value, &acpi_gbl_FADT.xpm_timer_block); + if (ACPI_SUCCESS(status)) { + + /* ACPI PM Timer is defined to be 32 bits (PM_TMR_LEN) */ + + *ticks = (u32)timer_value; + } + + return_ACPI_STATUS(status); +} + +ACPI_EXPORT_SYMBOL(acpi_get_timer) + +/****************************************************************************** + * + * FUNCTION: acpi_get_timer_duration + * + * PARAMETERS: start_ticks - Starting timestamp + * end_ticks - End timestamp + * time_elapsed - Where the elapsed time is returned + * + * RETURN: Status and time_elapsed + * + * DESCRIPTION: Computes the time elapsed (in microseconds) between two + * PM Timer time stamps, taking into account the possibility of + * rollovers, the timer resolution, and timer frequency. + * + * The PM Timer's clock ticks at roughly 3.6 times per + * _microsecond_, and its clock continues through Cx state + * transitions (unlike many CPU timestamp counters) -- making it + * a versatile and accurate timer. + * + * Note that this function accommodates only a single timer + * rollover. Thus for 24-bit timers, this function should only + * be used for calculating durations less than ~4.6 seconds + * (~20 minutes for 32-bit timers) -- calculations below: + * + * 2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec + * 2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes + * + ******************************************************************************/ +acpi_status +acpi_get_timer_duration(u32 start_ticks, u32 end_ticks, u32 *time_elapsed) +{ + acpi_status status; + u64 delta_ticks; + u64 quotient; + + ACPI_FUNCTION_TRACE(acpi_get_timer_duration); + + if (!time_elapsed) { + return_ACPI_STATUS(AE_BAD_PARAMETER); + } + + /* ACPI 5.0A: PM Timer is optional */ + + if (!acpi_gbl_FADT.xpm_timer_block.address) { + return_ACPI_STATUS(AE_SUPPORT); + } + + if (start_ticks == end_ticks) { + *time_elapsed = 0; + return_ACPI_STATUS(AE_OK); + } + + /* + * Compute Tick Delta: + * Handle (max one) timer rollovers on 24-bit versus 32-bit timers. + */ + delta_ticks = end_ticks; + if (start_ticks > end_ticks) { + if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) { + + /* 24-bit Timer */ + + delta_ticks |= (u64)1 << 24; + } else { + /* 32-bit Timer */ + + delta_ticks |= (u64)1 << 32; + } + } + delta_ticks -= start_ticks; + + /* + * Compute Duration (Requires a 64-bit multiply and divide): + * + * time_elapsed (microseconds) = + * (delta_ticks * ACPI_USEC_PER_SEC) / ACPI_PM_TIMER_FREQUENCY; + */ + status = acpi_ut_short_divide(delta_ticks * ACPI_USEC_PER_SEC, + ACPI_PM_TIMER_FREQUENCY, "ient, NULL); + + *time_elapsed = (u32)quotient; + return_ACPI_STATUS(status); +} + +ACPI_EXPORT_SYMBOL(acpi_get_timer_duration) +#endif /* !ACPI_REDUCED_HARDWARE */ -- cgit v1.3.1