forked from mirrors/linux
eac030b22e
lppaca_shared_proc() takes a pointer to the lppaca which is typically
accessed through get_lppaca(). With DEBUG_PREEMPT enabled, this leads
to checking if preemption is enabled, for example:
BUG: using smp_processor_id() in preemptible [00000000] code: grep/10693
caller is lparcfg_data+0x408/0x19a0
CPU: 4 PID: 10693 Comm: grep Not tainted 6.5.0-rc3 #2
Call Trace:
dump_stack_lvl+0x154/0x200 (unreliable)
check_preemption_disabled+0x214/0x220
lparcfg_data+0x408/0x19a0
...
This isn't actually a problem however, as it does not matter which
lppaca is accessed, the shared proc state will be the same.
vcpudispatch_stats_procfs_init() already works around this by disabling
preemption, but the lparcfg code does not, erroring any time
/proc/powerpc/lparcfg is accessed with DEBUG_PREEMPT enabled.
Instead of disabling preemption on the caller side, rework
lppaca_shared_proc() to not take a pointer and instead directly access
the lppaca, bypassing any potential preemption checks.
Fixes: f13c13a005 ("powerpc: Stop using non-architected shared_proc field in lppaca")
Signed-off-by: Russell Currey <ruscur@russell.cc>
[mpe: Rework to avoid needing a definition in paca.h and lppaca.h]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230823055317.751786-4-mpe@ellerman.id.au
143 lines
4.4 KiB
C
143 lines
4.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* lppaca.h
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* Copyright (C) 2001 Mike Corrigan IBM Corporation
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*/
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#ifndef _ASM_POWERPC_LPPACA_H
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#define _ASM_POWERPC_LPPACA_H
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#ifdef __KERNEL__
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/*
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* These definitions relate to hypervisors that only exist when using
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* a server type processor
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*/
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#ifdef CONFIG_PPC_BOOK3S
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/*
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* This control block contains the data that is shared between the
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* hypervisor and the OS.
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*/
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#include <linux/cache.h>
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#include <linux/threads.h>
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#include <asm/types.h>
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#include <asm/mmu.h>
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#include <asm/firmware.h>
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#include <asm/paca.h>
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/*
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* The lppaca is the "virtual processor area" registered with the hypervisor,
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* H_REGISTER_VPA etc.
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*
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* According to PAPR, the structure is 640 bytes long, must be L1 cache line
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* aligned, and must not cross a 4kB boundary. Its size field must be at
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* least 640 bytes (but may be more).
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*
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* Pre-v4.14 KVM hypervisors reject the VPA if its size field is smaller than
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* 1kB, so we dynamically allocate 1kB and advertise size as 1kB, but keep
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* this structure as the canonical 640 byte size.
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*/
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struct lppaca {
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/* cacheline 1 contains read-only data */
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__be32 desc; /* Eye catcher 0xD397D781 */
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__be16 size; /* Size of this struct */
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u8 reserved1[3];
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u8 __old_status; /* Old status, including shared proc */
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u8 reserved3[14];
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volatile __be32 dyn_hw_node_id; /* Dynamic hardware node id */
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volatile __be32 dyn_hw_proc_id; /* Dynamic hardware proc id */
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u8 reserved4[56];
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volatile u8 vphn_assoc_counts[8]; /* Virtual processor home node */
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/* associativity change counters */
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u8 reserved5[32];
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/* cacheline 2 contains local read-write data */
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u8 reserved6[48];
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u8 cede_latency_hint;
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u8 ebb_regs_in_use;
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u8 reserved7[6];
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u8 dtl_enable_mask; /* Dispatch Trace Log mask */
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u8 donate_dedicated_cpu; /* Donate dedicated CPU cycles */
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u8 fpregs_in_use;
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u8 pmcregs_in_use;
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u8 reserved8[28];
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__be64 wait_state_cycles; /* Wait cycles for this proc */
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u8 reserved9[28];
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__be16 slb_count; /* # of SLBs to maintain */
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u8 idle; /* Indicate OS is idle */
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u8 vmxregs_in_use;
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/* cacheline 3 is shared with other processors */
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/*
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* This is the yield_count. An "odd" value (low bit on) means that
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* the processor is yielded (either because of an OS yield or a
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* hypervisor preempt). An even value implies that the processor is
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* currently executing.
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* NOTE: Even dedicated processor partitions can yield so this
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* field cannot be used to determine if we are shared or dedicated.
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*/
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volatile __be32 yield_count;
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volatile __be32 dispersion_count; /* dispatch changed physical cpu */
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volatile __be64 cmo_faults; /* CMO page fault count */
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volatile __be64 cmo_fault_time; /* CMO page fault time */
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u8 reserved10[64]; /* [S]PURR expropriated/donated */
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volatile __be64 enqueue_dispatch_tb; /* Total TB enqueue->dispatch */
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volatile __be64 ready_enqueue_tb; /* Total TB ready->enqueue */
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volatile __be64 wait_ready_tb; /* Total TB wait->ready */
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u8 reserved11[16];
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/* cacheline 4-5 */
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__be32 page_ins; /* CMO Hint - # page ins by OS */
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u8 reserved12[148];
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volatile __be64 dtl_idx; /* Dispatch Trace Log head index */
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u8 reserved13[96];
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} ____cacheline_aligned;
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#define lppaca_of(cpu) (*paca_ptrs[cpu]->lppaca_ptr)
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/*
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* We are using a non architected field to determine if a partition is
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* shared or dedicated. This currently works on both KVM and PHYP, but
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* we will have to transition to something better.
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*/
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#define LPPACA_OLD_SHARED_PROC 2
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#ifdef CONFIG_PPC_PSERIES
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/*
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* All CPUs should have the same shared proc value, so directly access the PACA
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* to avoid false positives from DEBUG_PREEMPT.
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*/
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static inline bool lppaca_shared_proc(void)
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{
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struct lppaca *l = local_paca->lppaca_ptr;
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if (!firmware_has_feature(FW_FEATURE_SPLPAR))
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return false;
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return !!(l->__old_status & LPPACA_OLD_SHARED_PROC);
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}
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#define get_lppaca() (get_paca()->lppaca_ptr)
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#endif
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/*
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* SLB shadow buffer structure as defined in the PAPR. The save_area
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* contains adjacent ESID and VSID pairs for each shadowed SLB. The
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* ESID is stored in the lower 64bits, then the VSID.
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*/
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struct slb_shadow {
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__be32 persistent; /* Number of persistent SLBs */
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__be32 buffer_length; /* Total shadow buffer length */
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__be64 reserved;
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struct {
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__be64 esid;
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__be64 vsid;
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} save_area[SLB_NUM_BOLTED];
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} ____cacheline_aligned;
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#endif /* CONFIG_PPC_BOOK3S */
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#endif /* __KERNEL__ */
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#endif /* _ASM_POWERPC_LPPACA_H */
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