From ab2579d79529b8ed34f26a374a352f12ce24d5df Mon Sep 17 00:00:00 2001 From: Huacai Chen <chenhuacai@loongson.cn> Date: Thu, 11 Aug 2022 20:52:12 +0800 Subject: [PATCH] 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> --- arch/loongarch/kernel/head.S | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S index 7062cdf0e33e5..c60eb66793e35 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) -- GitLab