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| author | Ahmad Fatoum <a.fatoum@pengutronix.de> | 2022-10-24 08:57:13 +0200 |
|---|---|---|
| committer | Sascha Hauer <s.hauer@pengutronix.de> | 2022-10-26 06:21:43 +0200 |
| commit | 2d68037eb90ad8dab6402da04c7fc66f798b159f (patch) | |
| tree | 11cd9d85e5cde81266c21b0694427d3588a3cfbe /arch/arm/lib/pbl.lds.S | |
| parent | eee1b8846b0788c866dabf04e85742a48662455f (diff) | |
| download | barebox-2d68037eb90ad8dab6402da04c7fc66f798b159f.tar.gz barebox-2d68037eb90ad8dab6402da04c7fc66f798b159f.tar.xz | |
ARM64: asm: rewrite ENTRY_FUNCTION(_WITHSTACK) fully in assembly
Recent episode with pointer authentication showed again that for
platforms without __attribute__((naked)), we are better off writing
the early header in assembly. We still want to keep the board specific
entry points in C for ease of use, so we have ENTRY_FUNCTION_WITHSTACK
generate two symbols:
- A 32-bit stack top value that's placed in .rodata
- An entry point with the normal C code, including stack-using
prologues
The new common assembly head code will access the stack pointer in a
position-independent manner and set it up, before continuing with the
C code. The barebox header is part of the common assembly head code
ensuring it's not moved around due to compiler code generation.
The common code will need access to board-specific entry point and stack
top. The former is readily available as the alias __pbl_board_entry.
The latter is a bit more complicated, as the symbol may not exist for
boards not using the common header in a multi-image build.
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20221024065716.1215046-6-a.fatoum@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat (limited to 'arch/arm/lib/pbl.lds.S')
| -rw-r--r-- | arch/arm/lib/pbl.lds.S | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/arm/lib/pbl.lds.S b/arch/arm/lib/pbl.lds.S index ae1babdcfd..114ec7bc81 100644 --- a/arch/arm/lib/pbl.lds.S +++ b/arch/arm/lib/pbl.lds.S @@ -44,6 +44,15 @@ SECTIONS . = ALIGN(4); .rodata : { *(.rodata*) } + . = ALIGN(4); + __pbl_board_stack_top = .; + .rodata.pbl_board_stack_top : { + *(.pbl_board_stack_top_*) + /* Dummy for when BootROM sets up usable stack */ + LONG(0x00000000); + } + ASSERT(. - __pbl_board_stack_top <= 8, "Only One PBL per Image allowed") + .barebox_imd : { BAREBOX_IMD } _etext = .; /* End of text and rodata section */ |