/* ##### EMBASSY NOTE Originally from https://github.com/rust-embedded/cortex-m/blob/master/cortex-m-rt/link.x.in Adjusted to put everything in RAM */ /* # Developer notes - Symbols that start with a double underscore (__) are considered "private" - Symbols that start with a single underscore (_) are considered "semi-public"; they can be overridden in a user linker script, but should not be referred from user code (e.g. `extern "C" { static mut __sbss }`). - `EXTERN` forces the linker to keep a symbol in the final binary. We use this to make sure a symbol if not dropped if it appears in or near the front of the linker arguments and "it's not needed" by any of the preceding objects (linker arguments) - `PROVIDE` is used to provide default values that can be overridden by a user linker script - On alignment: it's important for correctness that the VMA boundaries of both .bss and .data *and* the LMA of .data are all 4-byte aligned. These alignments are assumed by the RAM initialization routine. There's also a second benefit: 4-byte aligned boundaries means that you won't see "Address (..) is out of bounds" in the disassembly produced by `objdump`. */ /* Provides information about the memory layout of the device */ /* This will be provided by the user (see `memory.x`) or by a Board Support Crate */ INCLUDE memory.x /* # Entry point = reset vector */ EXTERN(__RESET_VECTOR); EXTERN(Reset); ENTRY(Reset); /* # Exception vectors */ /* This is effectively weak aliasing at the linker level */ /* The user can override any of these aliases by defining the corresponding symbol themselves (cf. the `exception!` macro) */ EXTERN(__EXCEPTIONS); /* depends on all the these PROVIDED symbols */ EXTERN(DefaultHandler); PROVIDE(NonMaskableInt = DefaultHandler); EXTERN(HardFaultTrampoline); PROVIDE(MemoryManagement = DefaultHandler); PROVIDE(BusFault = DefaultHandler); PROVIDE(UsageFault = DefaultHandler); PROVIDE(SecureFault = DefaultHandler); PROVIDE(SVCall = DefaultHandler); PROVIDE(DebugMonitor = DefaultHandler); PROVIDE(PendSV = DefaultHandler); PROVIDE(SysTick = DefaultHandler); PROVIDE(DefaultHandler = DefaultHandler_); PROVIDE(HardFault = HardFault_); /* # Interrupt vectors */ EXTERN(__INTERRUPTS); /* `static` variable similar to `__EXCEPTIONS` */ /* # Pre-initialization function */ /* If the user overrides this using the `pre_init!` macro or by creating a `__pre_init` function, then the function this points to will be called before the RAM is initialized. */ PROVIDE(__pre_init = DefaultPreInit); /* # Sections */ SECTIONS { PROVIDE(_ram_start = ORIGIN(RAM)); PROVIDE(_ram_end = ORIGIN(RAM) + LENGTH(RAM)); PROVIDE(_stack_start = _ram_end); /* ## Sections in RAM */ /* ### Vector table */ .vector_table ORIGIN(RAM) : { __vector_table = .; /* Initial Stack Pointer (SP) value. * We mask the bottom three bits to force 8-byte alignment. * Despite having an assert for this later, it's possible that a separate * linker script could override _stack_start after the assert is checked. */ LONG(_stack_start & 0xFFFFFFF8); /* Reset vector */ KEEP(*(.vector_table.reset_vector)); /* this is the `__RESET_VECTOR` symbol */ /* Exceptions */ __exceptions = .; /* start of exceptions */ KEEP(*(.vector_table.exceptions)); /* this is the `__EXCEPTIONS` symbol */ __eexceptions = .; /* end of exceptions */ /* Device specific interrupts */ KEEP(*(.vector_table.interrupts)); /* this is the `__INTERRUPTS` symbol */ } > RAM PROVIDE(_stext = ADDR(.vector_table) + SIZEOF(.vector_table)); /* ### .text */ .text _stext : { __stext = .; *(.Reset); *(.text .text.*); /* The HardFaultTrampoline uses the `b` instruction to enter `HardFault`, so must be placed close to it. */ *(.HardFaultTrampoline); *(.HardFault.*); . = ALIGN(4); /* Pad .text to the alignment to workaround overlapping load section bug in old lld */ __etext = .; } > RAM /* ### .rodata */ .rodata : ALIGN(4) { . = ALIGN(4); __srodata = .; *(.rodata .rodata.*); /* 4-byte align the end (VMA) of this section. This is required by LLD to ensure the LMA of the following .data section will have the correct alignment. */ . = ALIGN(4); __erodata = .; } > RAM /* ## Sections in RAM */ /* ### .data */ .data : ALIGN(4) { . = ALIGN(4); __sdata = .; __edata = .; /* RAM: By setting __sdata=__edata cortex-m-rt has to copy 0 bytes as .data is already in RAM */ *(.data .data.*); . = ALIGN(4); /* 4-byte align the end (VMA) of this section */ } > RAM /* Allow sections from user `memory.x` injected using `INSERT AFTER .data` to * use the .data loading mechanism by pushing __edata. Note: do not change * output region or load region in those user sections! */ /* Link from RAM: Disabled, now __sdata == __edata . = ALIGN(4); __edata = .; */ /* LMA of .data */ __sidata = LOADADDR(.data); /* ### .gnu.sgstubs This section contains the TrustZone-M veneers put there by the Arm GNU linker. */ /* Security Attribution Unit blocks must be 32 bytes aligned. */ /* Note that this pads the RAM usage to 32 byte alignment. */ .gnu.sgstubs : ALIGN(32) { . = ALIGN(32); __veneer_base = .; *(.gnu.sgstubs*) . = ALIGN(32); } > RAM /* Place `__veneer_limit` outside the `.gnu.sgstubs` section because veneers are * always inserted last in the section, which would otherwise be _after_ the `__veneer_limit` symbol. */ . = ALIGN(32); __veneer_limit = .; /* ### .bss */ .bss (NOLOAD) : ALIGN(4) { . = ALIGN(4); __sbss = .; *(.bss .bss.*); *(COMMON); /* Uninitialized C statics */ . = ALIGN(4); /* 4-byte align the end (VMA) of this section */ } > RAM /* Allow sections from user `memory.x` injected using `INSERT AFTER .bss` to * use the .bss zeroing mechanism by pushing __ebss. Note: do not change * output region or load region in those user sections! */ . = ALIGN(4); __ebss = .; /* ### .uninit */ .uninit (NOLOAD) : ALIGN(4) { . = ALIGN(4); __suninit = .; *(.uninit .uninit.*); . = ALIGN(4); __euninit = .; } > RAM /* Place the heap right after `.uninit` in RAM */ PROVIDE(__sheap = __euninit); /* ## .got */ /* Dynamic relocations are unsupported. This section is only used to detect relocatable code in the input files and raise an error if relocatable code is found */ .got (NOLOAD) : { KEEP(*(.got .got.*)); } /* ## Discarded sections */ /DISCARD/ : { /* Unused exception related info that only wastes space */ *(.ARM.exidx); *(.ARM.exidx.*); *(.ARM.extab.*); } } /* Do not exceed this mark in the error messages below | */ /* # Alignment checks */ ASSERT(ORIGIN(RAM) % 4 == 0, " ERROR(cortex-m-rt): the start of the RAM region must be 4-byte aligned"); ASSERT(__sdata % 4 == 0 && __edata % 4 == 0, " BUG(cortex-m-rt): .data is not 4-byte aligned"); ASSERT(__sidata % 4 == 0, " BUG(cortex-m-rt): the LMA of .data is not 4-byte aligned"); ASSERT(__sbss % 4 == 0 && __ebss % 4 == 0, " BUG(cortex-m-rt): .bss is not 4-byte aligned"); ASSERT(__sheap % 4 == 0, " BUG(cortex-m-rt): start of .heap is not 4-byte aligned"); ASSERT(_stack_start % 8 == 0, " ERROR(cortex-m-rt): stack start address is not 8-byte aligned. If you have set _stack_start, check it's set to an address which is a multiple of 8 bytes. If you haven't, stack starts at the end of RAM by default. Check that both RAM origin and length are set to multiples of 8 in the `memory.x` file."); /* # Position checks */ /* ## .vector_table * * If the *start* of exception vectors is not 8 bytes past the start of the * vector table, then we somehow did not place the reset vector, which should * live 4 bytes past the start of the vector table. */ ASSERT(__exceptions == ADDR(.vector_table) + 0x8, " BUG(cortex-m-rt): the reset vector is missing"); ASSERT(__eexceptions == ADDR(.vector_table) + 0x40, " BUG(cortex-m-rt): the exception vectors are missing"); ASSERT(SIZEOF(.vector_table) > 0x40, " ERROR(cortex-m-rt): The interrupt vectors are missing. Possible solutions, from most likely to less likely: - Link to a svd2rust generated device crate - Check that you actually use the device/hal/bsp crate in your code - Disable the 'device' feature of cortex-m-rt to build a generic application (a dependency may be enabling it) - Supply the interrupt handlers yourself. Check the documentation for details."); /* ## .text */ ASSERT(ADDR(.vector_table) + SIZEOF(.vector_table) <= _stext, " ERROR(cortex-m-rt): The .text section can't be placed inside the .vector_table section Set _stext to an address greater than the end of .vector_table (See output of `nm`)"); ASSERT(_stext + SIZEOF(.text) < ORIGIN(RAM) + LENGTH(RAM), " ERROR(cortex-m-rt): The .text section must be placed inside the RAM memory. Set _stext to an address smaller than 'ORIGIN(RAM) + LENGTH(RAM)'"); /* # Other checks */ ASSERT(SIZEOF(.got) == 0, " ERROR(cortex-m-rt): .got section detected in the input object files Dynamic relocations are not supported. If you are linking to C code compiled using the 'cc' crate then modify your build script to compile the C code _without_ the -fPIC flag. See the documentation of the `cc::Build.pic` method for details."); /* Do not exceed this mark in the error messages above | */ /* Provides weak aliases (cf. PROVIDED) for device specific interrupt handlers */ /* This will usually be provided by a device crate generated using svd2rust (see `device.x`) */ INCLUDE device.x