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Move vector table to beginning of flash image (#10)

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* Move vector table to beginning of flash image. Modify a boot2 to use the table.

* Move binary info header up between ELF entry and reset handler

* Extract common routines from boot2_w25q080 into helper files

* Non-default boot2s: use common routines, make callable as void(*)(void)

* BSD3 headers on boot2 files (people might want to use them elsewhere)

* Promote binary info header to its own section, + comment/readability changes

* Fix scope of asminclude path (fixes user custom boot2 definitions)

* Rename symbol, clarify comment
This commit is contained in:
Luke Wren
2021-01-28 13:50:45 +00:00
committed by GitHub
parent 5e5776b9c0
commit 732b53271f
14 changed files with 229 additions and 267 deletions
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78
src/rp2_common/pico_standard_link/crt0.S
View File

@ -144,40 +144,61 @@ __unhandled_user_irq:
unhandled_user_irq_num_in_r0:
bkpt #0
.section .reset, "ax"
// ----------------------------------------------------------------------------
// This is the beginning of the image, which is entered from stage2 or bootrom USB MSD watchdog reboot
.section .binary_info_header, "a"
// note if we are NO_FLASH then start: below is currently identical anyway, so save 4 bytes
#if !PICO_NO_FLASH
// We simply install our own vector table and redirect through it
ldr r0, =__vectors
b __vector_entry
// Header must be in first 256 bytes of main image (i.e. excluding flash boot2).
// For flash builds we put it immediately after vector table; for NO_FLASH the
// vectors are at a +0x100 offset because the bootrom enters RAM images directly
// at their lowest address, so we put the header in the VTOR alignment hole.
#if !PICO_NO_BINARY_INFO
binary_info_header:
.word BINARY_INFO_MARKER_START
.word __binary_info_start
.word __binary_info_end
.word data_cpy_table // we may need to decode pointers that are in RAM at runtime.
.word BINARY_INFO_MARKER_END
#endif
// ELF entry point generally called when we load an ELF via debugger
// ----------------------------------------------------------------------------
.section .reset, "ax"
// On flash builds, the vector table comes first in the image (conventional).
// On NO_FLASH builds, the reset handler section comes first, as the entry
// point is at offset 0 (fixed due to bootrom), and VTOR is highly-aligned.
// Image is entered in various ways:
//
// - NO_FLASH builds are entered from beginning by UF2 bootloader
//
// - Flash builds vector through the table into _reset_handler from boot2
//
// - Either type can be entered via _entry_point by the debugger, and flash builds
// must then be sent back round the boot sequence to properly initialise flash
// ELF entry point:
.type _entry_point,%function
.thumb_func
.global _entry_point
_entry_point:
#if PICO_NO_FLASH
// non flash
// Vector through our own table (SP, VTOR will not have been set up at
// this point). Same path for debugger entry and bootloader entry.
ldr r0, =__vectors
#else
// todo clear watchdog?
// When using flash, we install and use the ROM vector table to go thru regular bootrom/stage2 flash sequence
// Debugger tried to run code after loading, so SSI is in 03h-only mode.
// Go back through bootrom + boot2 to properly initialise flash.
movs r0, #0
#endif
__vector_entry:
ldr r1, =(PPB_BASE + M0PLUS_CPUID_OFFSET)
str r0, [r1, #8]
ldr r1, =(PPB_BASE + M0PLUS_VTOR_OFFSET)
str r0, [r1]
ldmia r0!, {r1, r2}
msr msp, r1
bx r2
// ----------------------------------------------------------------------------
// Reset handler:
// - initialises .data
// - clears .bss
@ -188,11 +209,12 @@ __vector_entry:
.type _reset_handler,%function
.thumb_func
_reset_handler:
// Hang all cores except core 0
// Only core 0 should run the C runtime startup code; core 1 is normally
// sleeping in the bootrom at this point but check to be sure
ldr r0, =(SIO_BASE + SIO_CPUID_OFFSET)
ldr r0, [r0]
cmp r0, #0
bne wait_for_vector
bne hold_non_core0_in_bootrom
adr r4, data_cpy_table
@ -243,15 +265,6 @@ data_cpy:
blo data_cpy_loop
bx lr
#if !PICO_NO_BINARY_INFO
binary_info_header:
.word BINARY_INFO_MARKER_START
.word __binary_info_start
.word __binary_info_end
.word data_cpy_table // we may need to decode pointers that are in RAM at runtime.
.word BINARY_INFO_MARKER_END
#endif
.align 2
data_cpy_table:
#if PICO_COPY_TO_RAM
@ -284,11 +297,12 @@ runtime_init:
bx lr
// ----------------------------------------------------------------------------
// In case core 1's VTOR has already been moved into flash, we need to handle
// core 1 reset. However, we do so by just jumping back into bootrom version of
// wait_for_vector
// If core 1 somehow gets into crt0 due to a spectacular VTOR mishap, we need to
// catch it and send back to the sleep-and-launch code in the bootrom. Shouldn't
// happen (it should sleep in the ROM until given an entry point via the
// cross-core FIFOs) but it's good to be defensive.
wait_for_vector:
hold_non_core0_in_bootrom:
ldr r0, = 'W' | ('V' << 8)
bl rom_func_lookup
bx r0
@ -312,4 +326,4 @@ __get_current_exception:
.section .heap
.align 2
.equ HeapSize, PICO_HEAP_SIZE
.space HeapSize
.space HeapSize

11
src/rp2_common/pico_standard_link/memmap_blocked_ram.ld
View File

@ -59,12 +59,11 @@ SECTIONS
*/
.text : {
__reset_start = .;
KEEP (*(.reset))
. = ALIGN(256);
__reset_end = .;
ASSERT(__reset_end - __reset_start == 256, "ERROR: reset section should only be 256 bytes");
__logical_binary_start = .;
KEEP (*(.vectors))
KEEP (*(.binary_info_header))
__binary_info_header_end = .;
KEEP (*(.reset))
/* TODO revisit this now memset/memcpy/float in ROM */
/* bit of a hack right now to exclude all floating point and time critical (e.g. memset, memcpy) code from
* FLASH ... we will include any thing excluded here in .data below by default */
@ -246,6 +245,8 @@ SECTIONS
/* Check if data + heap + stack exceeds RAM limit */
ASSERT(__StackLimit >= __HeapLimit, "region RAM overflowed")
ASSERT( __binary_info_header_end - __logical_binary_start <= 256, "Binary info must be in first 256 bytes of the binary")
/* todo assert on extra code */
}

11
src/rp2_common/pico_standard_link/memmap_copy_to_ram.ld
View File

@ -59,12 +59,11 @@ SECTIONS
*/
.flashtext : {
__reset_start = .;
KEEP (*(.reset))
. = ALIGN(256);
__reset_end = .;
ASSERT(__reset_end - __reset_start == 256, "ERROR: reset section should only be 256 bytes");
__logical_binary_start = .;
KEEP (*(.vectors))
KEEP (*(.binary_info_header))
__binary_info_header_end = .;
KEEP (*(.reset))
}
.rodata : {
@ -247,6 +246,8 @@ SECTIONS
/* Check if data + heap + stack exceeds RAM limit */
ASSERT(__StackLimit >= __HeapLimit, "region RAM overflowed")
ASSERT( __binary_info_header_end - __logical_binary_start <= 256, "Binary info must be in first 256 bytes of the binary")
/* todo assert on extra code */
}

11
src/rp2_common/pico_standard_link/memmap_default.ld
View File

@ -59,12 +59,11 @@ SECTIONS
*/
.text : {
__reset_start = .;
KEEP (*(.reset))
. = ALIGN(256);
__reset_end = .;
ASSERT(__reset_end - __reset_start == 256, "ERROR: reset section should only be 256 bytes");
__logical_binary_start = .;
KEEP (*(.vectors))
KEEP (*(.binary_info_header))
__binary_info_header_end = .;
KEEP (*(.reset))
/* TODO revisit this now memset/memcpy/float in ROM */
/* bit of a hack right now to exclude all floating point and time critical (e.g. memset, memcpy) code from
* FLASH ... we will include any thing excluded here in .data below by default */
@ -246,6 +245,8 @@ SECTIONS
/* Check if data + heap + stack exceeds RAM limit */
ASSERT(__StackLimit >= __HeapLimit, "region RAM overflowed")
ASSERT( __binary_info_header_end - __logical_binary_start <= 256, "Binary info must be in first 256 bytes of the binary")
/* todo assert on extra code */
}

20
src/rp2_common/pico_standard_link/memmap_no_flash.ld
View File

@ -32,19 +32,21 @@ ENTRY(_entry_point)
SECTIONS
{
/* Watchdog reboot into RAM (via USB MSD will enter) image at the start of .text
The debugger will use the ELF entry point, which is the _entry_point
symbol if present, otherwise defaults to start of .text.
/* Note in NO_FLASH builds the entry point for both the bootrom, and debugger
entry (ELF entry point), are *first* in the image, and the vector table
follows immediately afterward. This is because the bootrom enters RAM
binaries directly at their lowest address (preferring main RAM over XIP
cache-as-SRAM if both are used).
*/
.text : {
__reset_start = .;
__logical_binary_start = .;
__reset_start = .;
KEEP (*(.reset))
/* reset should come first */
KEEP (*(.reset))
. = ALIGN(256);
__reset_end = .;
ASSERT(__reset_end - __reset_start == 256, "ERROR: reset section should only be 256 bytes");
KEEP (*(.binary_info_header))
__binary_info_header_end = .;
. = ALIGN(256);
KEEP (*(.vectors))
*(.time_critical*)
*(.text*)
@ -208,6 +210,8 @@ SECTIONS
/* Check if data + heap + stack exceeds RAM limit */
ASSERT(__StackLimit >= __HeapLimit, "region RAM overflowed")
ASSERT( __binary_info_header_end - __logical_binary_start <= 256, "Binary info must be in first 256 bytes of the binary")
/* todo assert on extra code */
}