From 172fa1601c7faaa01c547e8c498f5bdefd52d7cb Mon Sep 17 00:00:00 2001 From: Anup Patel Date: Wed, 9 Sep 2020 09:19:09 +0530 Subject: [PATCH] lib: sbi: Ensure coldboot HART supports next privilege mode The coldboot HART jumps to the next booting stage at the end of init_coldboot() so it is absolutely necessary for coldboot HART to support the privilege mode expected by the next booting stage. We extend the coldboot HART selection in sbi_init() to ensure that the selected coldboot HART always supports privilege mode specified in scratch space (i.e. scratch->next_mode). This will further help us allow E-core (without MMU) on SiFive Unleashed and PolarFire ICICLE boards to proceed further and wait in HSM STOPPED state. Signed-off-by: Anup Patel Reviewed-by: Atish Patra --- lib/sbi/sbi_init.c | 29 ++++++++++++++++++++++++++++- 1 file changed, 28 insertions(+), 1 deletion(-) diff --git a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c index e1a1d96..65d81ba 100644 --- a/lib/sbi/sbi_init.c +++ b/lib/sbi/sbi_init.c @@ -295,6 +295,7 @@ static atomic_t coldboot_lottery = ATOMIC_INITIALIZER(0); */ void __noreturn sbi_init(struct sbi_scratch *scratch) { + bool next_mode_supported = FALSE; bool coldboot = FALSE; u32 hartid = current_hartid(); const struct sbi_platform *plat = sbi_platform_ptr(scratch); @@ -303,7 +304,33 @@ void __noreturn sbi_init(struct sbi_scratch *scratch) sbi_platform_hart_invalid(plat, hartid)) sbi_hart_hang(); - if (atomic_xchg(&coldboot_lottery, 1) == 0) + switch (scratch->next_mode) { + case PRV_M: + next_mode_supported = TRUE; + break; + case PRV_S: + if (misa_extension('S')) + next_mode_supported = TRUE; + break; + case PRV_U: + if (misa_extension('U')) + next_mode_supported = TRUE; + break; + default: + sbi_hart_hang(); + } + + /* + * Only the HART supporting privilege mode specified in the + * scratch->next_mode should be allowed to become the coldboot + * HART because the coldboot HART will be directly jumping to + * the next booting stage. + * + * We use a lottery mechanism to select coldboot HART among + * HARTs which satisfy above condition. + */ + + if (next_mode_supported && atomic_xchg(&coldboot_lottery, 1) == 0) coldboot = TRUE; if (coldboot) -- 2.7.4