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Diffstat (limited to 'cortex-m-rt/link.x.in')
-rw-r--r-- | cortex-m-rt/link.x.in | 247 |
1 files changed, 247 insertions, 0 deletions
diff --git a/cortex-m-rt/link.x.in b/cortex-m-rt/link.x.in new file mode 100644 index 0000000..92004b7 --- /dev/null +++ b/cortex-m-rt/link.x.in @@ -0,0 +1,247 @@ +/* # 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(_stack_start = ORIGIN(RAM) + LENGTH(RAM)); + + /* ## Sections in FLASH */ + /* ### Vector table */ + .vector_table ORIGIN(FLASH) : + { + /* Initial Stack Pointer (SP) value */ + LONG(_stack_start); + + /* Reset vector */ + KEEP(*(.vector_table.reset_vector)); /* this is the `__RESET_VECTOR` symbol */ + __reset_vector = .; + + /* Exceptions */ + KEEP(*(.vector_table.exceptions)); /* this is the `__EXCEPTIONS` symbol */ + __eexceptions = .; + + /* Device specific interrupts */ + KEEP(*(.vector_table.interrupts)); /* this is the `__INTERRUPTS` symbol */ + } > FLASH + + 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 = .; + } > FLASH + + /* ### .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 = .; + } > FLASH + + /* ## Sections in RAM */ + /* ### .data */ + .data : ALIGN(4) + { + . = ALIGN(4); + __sdata = .; + *(.data .data.*); + . = ALIGN(4); /* 4-byte align the end (VMA) of this section */ + } > RAM AT>FLASH + /* 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! */ + . = 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 FLASH usage to 32 byte alignment. */ + .gnu.sgstubs : ALIGN(32) + { + . = ALIGN(32); + __veneer_base = .; + *(.gnu.sgstubs*) + . = ALIGN(32); + __veneer_limit = .; + } > FLASH + + /* ### .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(FLASH) % 4 == 0, " +ERROR(cortex-m-rt): the start of the FLASH region must be 4-byte aligned"); + +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"); + +/* # Position checks */ + +/* ## .vector_table */ +ASSERT(__reset_vector == 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(FLASH) + LENGTH(FLASH), " +ERROR(cortex-m-rt): The .text section must be placed inside the FLASH memory. +Set _stext to an address smaller than 'ORIGIN(FLASH) + LENGTH(FLASH)'"); + +/* # 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 | */ |