There are cases where a context synchronization event is necessary between an IRQ being raised and being handled, and there are races such that we cannot rely upon the exception entry being subsequent to the interrupt being raised. To fix this, we place an ISB between a read of IAR and the subsequent invocation of an IRQ handler. When EOI mode 1 is in use, we need to EOI an interrupt prior to invoking its handler, and we have a write to EOIR for this. As this write to EOIR requires an ISB, and this is provided by the gic_write_eoir() helper, we omit the usual ISB in this case, with the logic being: | if (static_branch_likely(&supports_deactivate_key)) | gic_write_eoir(irqnr); | else | isb(); This is somewhat opaque, and it would be a little clearer if there were an unconditional ISB, with only the write to EOIR being conditional, e.g. | if (static_branch_likely(&supports_deactivate_key)) | write_gicreg(irqnr, ICC_EOIR1_EL1); | | isb(); This patch rewrites the code that way, with this logic factored into a new helper function with comments explaining what the ISB is for, as were originally laid out in commit:39a06b67c2
("irqchip/gic: Ensure we have an ISB between ack and ->handle_irq") Note that since then, we removed the IAR polling in commit:342677d70a
("irqchip/gic-v3: Remove acknowledge loop") ... which removed one of the two race conditions. For consistency, other portions of the driver are made to manipulate EOIR using write_gicreg() and explcit ISBs, and the gic_write_eoir() helper function is removed. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20220513133038.226182-3-mark.rutland@arm.com
256 lines
6.2 KiB
C
256 lines
6.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* arch/arm/include/asm/arch_gicv3.h
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*
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* Copyright (C) 2015 ARM Ltd.
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*/
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#ifndef __ASM_ARCH_GICV3_H
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#define __ASM_ARCH_GICV3_H
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#ifndef __ASSEMBLY__
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#include <linux/io.h>
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#include <linux/io-64-nonatomic-lo-hi.h>
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#include <asm/barrier.h>
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#include <asm/cacheflush.h>
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#include <asm/cp15.h>
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#define ICC_EOIR1 __ACCESS_CP15(c12, 0, c12, 1)
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#define ICC_DIR __ACCESS_CP15(c12, 0, c11, 1)
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#define ICC_IAR1 __ACCESS_CP15(c12, 0, c12, 0)
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#define ICC_SGI1R __ACCESS_CP15_64(0, c12)
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#define ICC_PMR __ACCESS_CP15(c4, 0, c6, 0)
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#define ICC_CTLR __ACCESS_CP15(c12, 0, c12, 4)
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#define ICC_SRE __ACCESS_CP15(c12, 0, c12, 5)
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#define ICC_IGRPEN1 __ACCESS_CP15(c12, 0, c12, 7)
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#define ICC_BPR1 __ACCESS_CP15(c12, 0, c12, 3)
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#define ICC_RPR __ACCESS_CP15(c12, 0, c11, 3)
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#define __ICC_AP0Rx(x) __ACCESS_CP15(c12, 0, c8, 4 | x)
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#define ICC_AP0R0 __ICC_AP0Rx(0)
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#define ICC_AP0R1 __ICC_AP0Rx(1)
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#define ICC_AP0R2 __ICC_AP0Rx(2)
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#define ICC_AP0R3 __ICC_AP0Rx(3)
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#define __ICC_AP1Rx(x) __ACCESS_CP15(c12, 0, c9, x)
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#define ICC_AP1R0 __ICC_AP1Rx(0)
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#define ICC_AP1R1 __ICC_AP1Rx(1)
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#define ICC_AP1R2 __ICC_AP1Rx(2)
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#define ICC_AP1R3 __ICC_AP1Rx(3)
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#define CPUIF_MAP(a32, a64) \
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static inline void write_ ## a64(u32 val) \
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{ \
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write_sysreg(val, a32); \
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} \
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static inline u32 read_ ## a64(void) \
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{ \
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return read_sysreg(a32); \
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} \
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CPUIF_MAP(ICC_EOIR1, ICC_EOIR1_EL1)
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CPUIF_MAP(ICC_PMR, ICC_PMR_EL1)
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CPUIF_MAP(ICC_AP0R0, ICC_AP0R0_EL1)
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CPUIF_MAP(ICC_AP0R1, ICC_AP0R1_EL1)
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CPUIF_MAP(ICC_AP0R2, ICC_AP0R2_EL1)
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CPUIF_MAP(ICC_AP0R3, ICC_AP0R3_EL1)
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CPUIF_MAP(ICC_AP1R0, ICC_AP1R0_EL1)
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CPUIF_MAP(ICC_AP1R1, ICC_AP1R1_EL1)
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CPUIF_MAP(ICC_AP1R2, ICC_AP1R2_EL1)
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CPUIF_MAP(ICC_AP1R3, ICC_AP1R3_EL1)
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#define read_gicreg(r) read_##r()
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#define write_gicreg(v, r) write_##r(v)
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/* Low-level accessors */
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static inline void gic_write_dir(u32 val)
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{
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write_sysreg(val, ICC_DIR);
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isb();
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}
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static inline u32 gic_read_iar(void)
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{
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u32 irqstat = read_sysreg(ICC_IAR1);
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dsb(sy);
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return irqstat;
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}
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static inline void gic_write_ctlr(u32 val)
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{
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write_sysreg(val, ICC_CTLR);
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isb();
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}
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static inline u32 gic_read_ctlr(void)
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{
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return read_sysreg(ICC_CTLR);
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}
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static inline void gic_write_grpen1(u32 val)
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{
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write_sysreg(val, ICC_IGRPEN1);
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isb();
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}
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static inline void gic_write_sgi1r(u64 val)
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{
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write_sysreg(val, ICC_SGI1R);
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}
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static inline u32 gic_read_sre(void)
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{
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return read_sysreg(ICC_SRE);
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}
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static inline void gic_write_sre(u32 val)
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{
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write_sysreg(val, ICC_SRE);
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isb();
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}
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static inline void gic_write_bpr1(u32 val)
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{
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write_sysreg(val, ICC_BPR1);
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}
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static inline u32 gic_read_pmr(void)
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{
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return read_sysreg(ICC_PMR);
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}
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static inline void gic_write_pmr(u32 val)
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{
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write_sysreg(val, ICC_PMR);
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}
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static inline u32 gic_read_rpr(void)
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{
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return read_sysreg(ICC_RPR);
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}
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/*
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* Even in 32bit systems that use LPAE, there is no guarantee that the I/O
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* interface provides true 64bit atomic accesses, so using strd/ldrd doesn't
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* make much sense.
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* Moreover, 64bit I/O emulation is extremely difficult to implement on
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* AArch32, since the syndrome register doesn't provide any information for
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* them.
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* Consequently, the following IO helpers use 32bit accesses.
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*/
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static inline void __gic_writeq_nonatomic(u64 val, volatile void __iomem *addr)
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{
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writel_relaxed((u32)val, addr);
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writel_relaxed((u32)(val >> 32), addr + 4);
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}
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static inline u64 __gic_readq_nonatomic(const volatile void __iomem *addr)
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{
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u64 val;
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val = readl_relaxed(addr);
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val |= (u64)readl_relaxed(addr + 4) << 32;
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return val;
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}
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#define gic_flush_dcache_to_poc(a,l) __cpuc_flush_dcache_area((a), (l))
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/*
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* GICD_IROUTERn, contain the affinity values associated to each interrupt.
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* The upper-word (aff3) will always be 0, so there is no need for a lock.
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*/
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#define gic_write_irouter(v, c) __gic_writeq_nonatomic(v, c)
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/*
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* GICR_TYPER is an ID register and doesn't need atomicity.
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*/
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#define gic_read_typer(c) __gic_readq_nonatomic(c)
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/*
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* GITS_BASER - hi and lo bits may be accessed independently.
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*/
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#define gits_read_baser(c) __gic_readq_nonatomic(c)
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#define gits_write_baser(v, c) __gic_writeq_nonatomic(v, c)
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/*
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* GICR_PENDBASER and GICR_PROPBASE are changed with LPIs disabled, so they
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* won't be being used during any updates and can be changed non-atomically
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*/
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#define gicr_read_propbaser(c) __gic_readq_nonatomic(c)
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#define gicr_write_propbaser(v, c) __gic_writeq_nonatomic(v, c)
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#define gicr_read_pendbaser(c) __gic_readq_nonatomic(c)
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#define gicr_write_pendbaser(v, c) __gic_writeq_nonatomic(v, c)
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/*
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* GICR_xLPIR - only the lower bits are significant
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*/
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#define gic_read_lpir(c) readl_relaxed(c)
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#define gic_write_lpir(v, c) writel_relaxed(lower_32_bits(v), c)
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/*
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* GITS_TYPER is an ID register and doesn't need atomicity.
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*/
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#define gits_read_typer(c) __gic_readq_nonatomic(c)
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/*
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* GITS_CBASER - hi and lo bits may be accessed independently.
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*/
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#define gits_read_cbaser(c) __gic_readq_nonatomic(c)
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#define gits_write_cbaser(v, c) __gic_writeq_nonatomic(v, c)
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/*
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* GITS_CWRITER - hi and lo bits may be accessed independently.
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*/
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#define gits_write_cwriter(v, c) __gic_writeq_nonatomic(v, c)
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/*
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* GICR_VPROPBASER - hi and lo bits may be accessed independently.
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*/
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#define gicr_read_vpropbaser(c) __gic_readq_nonatomic(c)
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#define gicr_write_vpropbaser(v, c) __gic_writeq_nonatomic(v, c)
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/*
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* GICR_VPENDBASER - the Valid bit must be cleared before changing
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* anything else.
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*/
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static inline void gicr_write_vpendbaser(u64 val, void __iomem *addr)
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{
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u32 tmp;
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tmp = readl_relaxed(addr + 4);
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if (tmp & (GICR_VPENDBASER_Valid >> 32)) {
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tmp &= ~(GICR_VPENDBASER_Valid >> 32);
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writel_relaxed(tmp, addr + 4);
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}
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/*
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* Use the fact that __gic_writeq_nonatomic writes the second
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* half of the 64bit quantity after the first.
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*/
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__gic_writeq_nonatomic(val, addr);
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}
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#define gicr_read_vpendbaser(c) __gic_readq_nonatomic(c)
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static inline bool gic_prio_masking_enabled(void)
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{
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return false;
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}
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static inline void gic_pmr_mask_irqs(void)
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{
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/* Should not get called. */
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WARN_ON_ONCE(true);
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}
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static inline void gic_arch_enable_irqs(void)
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{
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/* Should not get called. */
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WARN_ON_ONCE(true);
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}
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#endif /* !__ASSEMBLY__ */
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#endif /* !__ASM_ARCH_GICV3_H */
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