From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Jones Date: Wed, 26 Apr 2023 19:27:53 +0200 Subject: [PATCH] lib: sbi: Ensure SBI extension is available Message-ID: <20230426172753.70664-1-ajones@ventanamicro.com> List-Id: To: opensbi@lists.infradead.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Ensure attempts to invoke SBI extension functions fail with SBI_ERR_NOT_SUPPORTED when the extension's probe function has reported that the extension is not available. By adding a new status member to the extension which has three states (uninitialized, available, unavailable), we ensure that the probe function is only invoked once, lazily, upon first use. Signed-off-by: Andrew Jones --- include/sbi/sbi_ecall.h | 6 ++++++ lib/sbi/sbi_ecall.c | 18 ++++++++++++++---- 2 files changed, 20 insertions(+), 4 deletions(-) diff --git a/include/sbi/sbi_ecall.h b/include/sbi/sbi_ecall.h index ff9bf8e2b435..8e31d0d91620 100644 --- a/include/sbi/sbi_ecall.h +++ b/include/sbi/sbi_ecall.h @@ -20,10 +20,16 @@ struct sbi_trap_regs; struct sbi_trap_info; +enum sbi_ext_status { + SBI_EXT_AVAILABLE = 1, + SBI_EXT_UNAVAILABLE, +}; + struct sbi_ecall_extension { struct sbi_dlist head; unsigned long extid_start; unsigned long extid_end; + enum sbi_ext_status status; int (* probe)(unsigned long extid, unsigned long *out_val); int (* handle)(unsigned long extid, unsigned long funcid, const struct sbi_trap_regs *regs, diff --git a/lib/sbi/sbi_ecall.c b/lib/sbi/sbi_ecall.c index 76a1ae9ab733..20ff06f32dad 100644 --- a/lib/sbi/sbi_ecall.c +++ b/lib/sbi/sbi_ecall.c @@ -42,16 +42,26 @@ static SBI_LIST_HEAD(ecall_exts_list); struct sbi_ecall_extension *sbi_ecall_find_extension(unsigned long extid) { - struct sbi_ecall_extension *t, *ret = NULL; + struct sbi_ecall_extension *t; + unsigned long out_val; sbi_list_for_each_entry(t, &ecall_exts_list, head) { if (t->extid_start <= extid && extid <= t->extid_end) { - ret = t; - break; + if (t->status == SBI_EXT_AVAILABLE) + return t; + if (t->status == SBI_EXT_UNAVAILABLE) + return NULL; + if (t->probe && (t->probe(extid, &out_val) || !out_val)) { + t->status = SBI_EXT_UNAVAILABLE; + return NULL; + } + + t->status = SBI_EXT_AVAILABLE; + return t; } } - return ret; + return NULL; } int sbi_ecall_register_extension(struct sbi_ecall_extension *ext) -- 2.39.2