diff options
| author | Ard Biesheuvel <ardb@kernel.org> | 2020-04-13 18:21:35 +0200 |
|---|---|---|
| committer | Ard Biesheuvel <ardb@kernel.org> | 2020-05-19 18:23:22 +0200 |
| commit | d0f9ca9be11f25ef4151195eab7ea36d136084f6 (patch) | |
| tree | 842ac1c29d90b20a67b1d1f535246b707189c758 /arch/arm | |
| parent | ARM: decompressor: move GOT into .data for EFI enabled builds (diff) | |
| download | linux-d0f9ca9be11f25ef4151195eab7ea36d136084f6.tar.xz linux-d0f9ca9be11f25ef4151195eab7ea36d136084f6.zip | |
ARM: decompressor: run decompressor in place if loaded via UEFI
The decompressor can load from anywhere in memory, and the only reason
the EFI stub code relocates it is to ensure it appears within the first
128 MiB of memory, so that the uncompressed kernel ends up at the right
offset in memory.
We can short circuit this, and simply jump into the decompressor startup
code at the point where it knows where the base of memory lives. This
also means there is no need to disable the MMU and caches, create new
page tables and re-enable them.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/boot/compressed/head.S | 39 |
1 files changed, 14 insertions, 25 deletions
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S index ce442ec5028a..c79db44ba128 100644 --- a/arch/arm/boot/compressed/head.S +++ b/arch/arm/boot/compressed/head.S @@ -1430,37 +1430,26 @@ reloc_code_end: #ifdef CONFIG_EFI_STUB ENTRY(efi_enter_kernel) - mov r7, r0 @ preserve image base - mov r4, r1 @ preserve DT pointer + mov r4, r0 @ preserve image base + mov r8, r1 @ preserve DT pointer - mov r0, r4 @ DT start - add r1, r4, r2 @ DT end - bl cache_clean_flush + mrc p15, 0, r0, c1, c0, 0 @ read SCTLR + tst r0, #0x1 @ MMU enabled? + orreq r4, r4, #1 @ set LSB if not - mov r0, r7 @ relocated zImage - ldr r1, =_edata @ size of zImage - add r1, r1, r0 @ end of zImage + mov r0, r8 @ DT start + add r1, r8, r2 @ DT end bl cache_clean_flush - @ The PE/COFF loader might not have cleaned the code we are - @ running beyond the PoU, and so calling cache_off below from - @ inside the PE/COFF loader allocated region is unsafe unless - @ we explicitly clean it to the PoC. - adr r0, call_cache_fn @ region of code we will - adr r1, 0f @ run with MMU off - bl cache_clean_flush - bl cache_off + adr r0, 0f @ switch to our stack + ldr sp, [r0] + add sp, sp, r0 - @ Set parameters for booting zImage according to boot protocol - @ put FDT address in r2, it was returned by efi_entry() - @ r1 is the machine type, and r0 needs to be 0 - mov r0, #0 - mov r1, #0xFFFFFFFF - mov r2, r4 - add r7, r7, #(__efi_start - start) - mov pc, r7 @ no mode switch + mov r5, #0 @ appended DTB size + mov r7, #0xFFFFFFFF @ machine ID + b wont_overwrite ENDPROC(efi_enter_kernel) -0: +0: .long .L_user_stack_end - . #endif .align |