diff options
| author | Huacai Chen <chenhuacai@loongson.cn> | 2022-08-11 20:52:12 +0800 |
|---|---|---|
| committer | Huacai Chen <chenhuacai@loongson.cn> | 2022-08-12 13:10:11 +0800 |
| commit | ab2579d79529b8ed34f26a374a352f12ce24d5df (patch) | |
| tree | 479868eddc4b104801cf4c657daac305c9e5a0be | |
| parent | 5e8be07ca8f7f49d49c6d5d44f69caaa2fa4b660 (diff) | |
| download | linux-ab2579d79529b8ed34f26a374a352f12ce24d5df.tar.gz | |
LoongArch: Jump to the link address before enable PG
The kernel entry points of both boot CPU (i.e., kernel_entry) and non-
boot CPUs (i.e., smpboot_entry) may be physical address from BootLoader
(in DA mode or identity-mapping PG mode). So we should jump to the link
address before PG enabled (because DA is disabled at the same time) and
just after DMW configured.
Specifically: With some older firmwares, non-boot CPUs started with PG
enabled, but this need firmware cooperation in the form of a temporary
page table, which is deemed unnecessary. OTOH, latest firmware versions
configure the non-boot CPUs to start in DA mode, so kernel-side changes
are needed.
Reviewed-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
| -rw-r--r-- | arch/loongarch/kernel/head.S | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S index 7062cdf0e33e59..c60eb66793e351 100644 --- a/arch/loongarch/kernel/head.S +++ b/arch/loongarch/kernel/head.S @@ -21,6 +21,12 @@ SYM_CODE_START(kernel_entry) # kernel entry point csrwr t0, LOONGARCH_CSR_DMWIN0 li.d t0, CSR_DMW1_INIT # CA, PLV0, 0x9000 xxxx xxxx xxxx csrwr t0, LOONGARCH_CSR_DMWIN1 + + /* We might not get launched at the address the kernel is linked to, + so we jump there. */ + la.abs t0, 0f + jr t0 +0: /* Enable PG */ li.w t0, 0xb0 # PLV=0, IE=0, PG=1 csrwr t0, LOONGARCH_CSR_CRMD @@ -29,11 +35,6 @@ SYM_CODE_START(kernel_entry) # kernel entry point li.w t0, 0x00 # FPE=0, SXE=0, ASXE=0, BTE=0 csrwr t0, LOONGARCH_CSR_EUEN - /* We might not get launched at the address the kernel is linked to, - so we jump there. */ - la.abs t0, 0f - jr t0 -0: la t0, __bss_start # clear .bss st.d zero, t0, 0 la t1, __bss_stop - LONGSIZE @@ -74,6 +75,11 @@ SYM_CODE_START(smpboot_entry) csrwr t0, LOONGARCH_CSR_DMWIN0 li.d t0, CSR_DMW1_INIT # CA, PLV0 csrwr t0, LOONGARCH_CSR_DMWIN1 + + la.abs t0, 0f + jr t0 +0: + /* Enable PG */ li.w t0, 0xb0 # PLV=0, IE=0, PG=1 csrwr t0, LOONGARCH_CSR_CRMD li.w t0, 0x04 # PLV=0, PIE=1, PWE=0 @@ -85,9 +91,6 @@ SYM_CODE_START(smpboot_entry) ld.d sp, t0, CPU_BOOT_STACK ld.d tp, t0, CPU_BOOT_TINFO - la.abs t0, 0f - jr t0 -0: bl start_secondary SYM_CODE_END(smpboot_entry) |