09e7987121
There is currently a big problem in the address environment handling which is that the address environment is released too soon when the process is exiting. The current MMU mappings will always be the exiting process's, which means the system needs them AT LEAST until the next context switch happens. If the next thread is a kernel thread, the address environment is needed for longer. Kernel threads "lend" the address environment of the previous user process. This is beneficial in two ways: - The kernel processes do not need an allocated address environment - When a context switch happens from user -> kernel or kernel -> kernel, the TLB does not need to be flushed. This must be done only when changing to a different user address environment. Another issue is when a new process is created; the address environment of the new process must be temporarily instantiated by up_addrenv_select(). However, the system scheduler does not know that the process has a different address environment to its own and when / if a context restore happens, the wrong MMU page directory is restored and the process will either crash or do something horribly wrong. The following changes are needed to fix the issues: - Add mm_curr which is the current address environment of the process - Add a reference counter to safeguard the address environment - Whenever an address environment is mapped to MMU, its reference counter is incremented - Whenever and address environment is unmapped from MMU, its reference counter is decremented, and tested. If no more references -> drop the address environment and release the memory as well - To limit the context switch delay, the address environment is freed in a separate low priority clean-up thread (LPWORK) - When a process temporarily instantiates another process's address environment, the scheduler will now know of this and will restore the correct mappings to MMU Why is this not causing more noticeable issues ? The problem only happens under the aforementioned special conditions, and if a context switch or IRQ occurs during this time.
87 lines
2.3 KiB
Plaintext
87 lines
2.3 KiB
Plaintext
#
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# This file is autogenerated: PLEASE DO NOT EDIT IT.
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#
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# You can use "make menuconfig" to make any modifications to the installed .config file.
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# You can then do "make savedefconfig" to generate a new defconfig file that includes your
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# modifications.
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#
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# CONFIG_MMCSD_MMCSUPPORT is not set
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# CONFIG_SAMA5_UART0 is not set
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CONFIG_ARCH="arm"
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CONFIG_ARCH_ADDRENV=y
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CONFIG_ARCH_BOARD="sama5d4-ek"
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CONFIG_ARCH_BOARD_SAMA5D4_EK=y
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CONFIG_ARCH_BUTTONS=y
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CONFIG_ARCH_CHIP="sama5"
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CONFIG_ARCH_CHIP_ATSAMA5D44=y
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CONFIG_ARCH_CHIP_SAMA5=y
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CONFIG_ARCH_CHIP_SAMA5D4=y
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CONFIG_ARCH_DATA_NPAGES=256
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CONFIG_ARCH_DATA_VBASE=0x80100000
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CONFIG_ARCH_HEAP_NPAGES=256
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CONFIG_ARCH_HEAP_VBASE=0x80200000
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CONFIG_ARCH_INTERRUPTSTACK=2048
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CONFIG_ARCH_IRQBUTTONS=y
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CONFIG_ARCH_LOWVECTORS=y
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CONFIG_ARCH_PGPOOL_MAPPING=y
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CONFIG_ARCH_PGPOOL_PBASE=0x28000000
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CONFIG_ARCH_PGPOOL_SIZE=134217728
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CONFIG_ARCH_PGPOOL_VBASE=0x28000000
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CONFIG_ARCH_STACKDUMP=y
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CONFIG_ARCH_TEXT_NPAGES=256
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CONFIG_ARCH_TEXT_VBASE=0x80000000
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CONFIG_BOARD_LATE_INITIALIZE=y
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CONFIG_BOARD_LOOPSPERMSEC=65775
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CONFIG_BOOT_RUNFROMSDRAM=y
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CONFIG_BUILD_KERNEL=y
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CONFIG_DEV_ZERO=y
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CONFIG_ELF=y
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CONFIG_EXAMPLES_HELLO=y
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CONFIG_FAT_LCNAMES=y
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CONFIG_FAT_LFN=y
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CONFIG_FS_FAT=y
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CONFIG_FS_PROCFS=y
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CONFIG_FS_ROMFS=y
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CONFIG_HAVE_CXX=y
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CONFIG_HAVE_CXXINITIALIZE=y
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CONFIG_HOST_WINDOWS=y
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CONFIG_INTELHEX_BINARY=y
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CONFIG_LIBC_EXECFUNCS=y
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CONFIG_LIBC_MAX_EXITFUNS=2
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CONFIG_MMCSD=y
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CONFIG_MMCSD_MULTIBLOCK_LIMIT=1
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CONFIG_MMCSD_SDIO=y
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CONFIG_MM_PGALLOC=y
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CONFIG_NSH_FILE_APPS=y
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CONFIG_NSH_READLINE=y
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CONFIG_PREALLOC_TIMERS=4
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CONFIG_RAM_SIZE=268435456
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CONFIG_RAM_START=0x20000000
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CONFIG_RAM_VSTART=0x20000000
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CONFIG_RAW_BINARY=y
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CONFIG_RR_INTERVAL=200
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CONFIG_SAMA5D4EK_528MHZ=y
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CONFIG_SAMA5D4EK_HSMCI0_MOUNT=y
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CONFIG_SAMA5_BOOT_SDRAM=y
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CONFIG_SAMA5_DDRCS_HEAP_END=0x28000000
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CONFIG_SAMA5_DDRCS_PGHEAP_OFFSET=0x08000000
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CONFIG_SAMA5_DDRCS_PGHEAP_SIZE=134217728
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CONFIG_SAMA5_DDRCS_RESERVE=y
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CONFIG_SAMA5_HSMCI0=y
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CONFIG_SAMA5_PIOE_IRQ=y
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CONFIG_SAMA5_PIO_IRQ=y
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CONFIG_SAMA5_RTC=y
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CONFIG_SAMA5_TRNG=y
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CONFIG_SAMA5_USART3=y
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CONFIG_SAMA5_USART4=y
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CONFIG_SAMA5_XDMAC0=y
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CONFIG_SCHED_HAVE_PARENT=y
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CONFIG_SCHED_HPWORK=y
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CONFIG_SCHED_HPWORKPRIORITY=192
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CONFIG_SCHED_LPWORK=y
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CONFIG_SCHED_WAITPID=y
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CONFIG_SDIO_BLOCKSETUP=y
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CONFIG_SYSTEM_NSH=y
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CONFIG_SYSTEM_NSH_PROGNAME="init"
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CONFIG_USART3_SERIAL_CONSOLE=y
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