From af8bc68263b2184e63ee67ca70cecff4636f7901 Mon Sep 17 00:00:00 2001 From: Nathan Lynch Date: Mon, 6 Mar 2023 15:33:45 -0600 Subject: powerpc/rtas: lockdep annotations Add lockdep annotations for the following properties that must hold: * Any error log retrieval must be atomically coupled with the prior RTAS call, without a window for another RTAS call to occur before the error log can be retrieved. * All users of the core rtas_args parameter block must hold rtas_lock. Move the definitions of rtas_lock and rtas_args up in the file so that __do_enter_rtas_trace() can refer to them. Signed-off-by: Nathan Lynch Reviewed-by: Andrew Donnellan Signed-off-by: Michael Ellerman Link: https://msgid.link/20230220-rtas-queue-for-6-4-v1-6-010e4416f13f@linux.ibm.com --- arch/powerpc/kernel/rtas.c | 33 +++++++++++++++++++++++---------- 1 file changed, 23 insertions(+), 10 deletions(-) (limited to 'arch/powerpc/kernel') diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c index c29c38b1a55a..c087eeee320f 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include #include @@ -453,6 +454,16 @@ static struct rtas_function rtas_function_table[] __ro_after_init = { }, }; +/* + * Nearly all RTAS calls need to be serialized. All uses of the + * default rtas_args block must hold rtas_lock. + * + * Exceptions to the RTAS serialization requirement (e.g. stop-self) + * must use a separate rtas_args structure. + */ +static DEFINE_RAW_SPINLOCK(rtas_lock); +static struct rtas_args rtas_args; + /** * rtas_function_token() - RTAS function token lookup. * @handle: Function handle, e.g. RTAS_FN_EVENT_SCAN. @@ -560,6 +571,9 @@ static void __do_enter_rtas(struct rtas_args *args) static void __do_enter_rtas_trace(struct rtas_args *args) { const char *name = NULL; + + if (args == &rtas_args) + lockdep_assert_held(&rtas_lock); /* * If the tracepoints that consume the function name aren't * active, avoid the lookup. @@ -619,16 +633,6 @@ static void do_enter_rtas(struct rtas_args *args) struct rtas_t rtas; -/* - * Nearly all RTAS calls need to be serialized. All uses of the - * default rtas_args block must hold rtas_lock. - * - * Exceptions to the RTAS serialization requirement (e.g. stop-self) - * must use a separate rtas_args structure. - */ -static DEFINE_RAW_SPINLOCK(rtas_lock); -static struct rtas_args rtas_args; - DEFINE_SPINLOCK(rtas_data_buf_lock); EXPORT_SYMBOL_GPL(rtas_data_buf_lock); @@ -951,6 +955,8 @@ static char *__fetch_rtas_last_error(char *altbuf) u32 bufsz; char *buf = NULL; + lockdep_assert_held(&rtas_lock); + if (token == -1) return NULL; @@ -1108,6 +1114,7 @@ static bool token_is_restricted_errinjct(s32 token) */ int rtas_call(int token, int nargs, int nret, int *outputs, ...) { + struct pin_cookie cookie; va_list list; int i; unsigned long flags; @@ -1134,6 +1141,8 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...) } raw_spin_lock_irqsave(&rtas_lock, flags); + cookie = lockdep_pin_lock(&rtas_lock); + /* We use the global rtas args buffer */ args = &rtas_args; @@ -1151,6 +1160,7 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...) outputs[i] = be32_to_cpu(args->rets[i + 1]); ret = (nret > 0) ? be32_to_cpu(args->rets[0]) : 0; + lockdep_unpin_lock(&rtas_lock, cookie); raw_spin_unlock_irqrestore(&rtas_lock, flags); if (buff_copy) { @@ -1782,6 +1792,7 @@ err: /* We assume to be passed big endian arguments */ SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs) { + struct pin_cookie cookie; struct rtas_args args; unsigned long flags; char *buff_copy, *errbuf = NULL; @@ -1850,6 +1861,7 @@ SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs) buff_copy = get_errorlog_buffer(); raw_spin_lock_irqsave(&rtas_lock, flags); + cookie = lockdep_pin_lock(&rtas_lock); rtas_args = args; do_enter_rtas(&rtas_args); @@ -1860,6 +1872,7 @@ SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs) if (be32_to_cpu(args.rets[0]) == -1) errbuf = __fetch_rtas_last_error(buff_copy); + lockdep_unpin_lock(&rtas_lock, cookie); raw_spin_unlock_irqrestore(&rtas_lock, flags); if (buff_copy) { -- cgit v1.2.3