From c13ff6f3251318f5e1ff5b1a6d05f76996db672a Mon Sep 17 00:00:00 2001 From: Nathan Lynch Date: Thu, 8 Apr 2021 09:06:26 -0500 Subject: powerpc/rtas: improve ppc_rtas_rmo_buf_show documentation Add kerneldoc for ppc_rtas_rmo_buf_show(), the callback for /proc/powerpc/rtas/rmo_buffer, explaining its expected use. Signed-off-by: Nathan Lynch Reviewed-by: Alexey Kardashevskiy Reviewed-by: Andrew Donnellan Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210408140630.205502-2-nathanl@linux.ibm.com --- arch/powerpc/kernel/rtas-proc.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'arch/powerpc') diff --git a/arch/powerpc/kernel/rtas-proc.c b/arch/powerpc/kernel/rtas-proc.c index 2d33f342a293..e0f8329966d6 100644 --- a/arch/powerpc/kernel/rtas-proc.c +++ b/arch/powerpc/kernel/rtas-proc.c @@ -757,7 +757,16 @@ static int ppc_rtas_tone_volume_show(struct seq_file *m, void *v) #define RMO_READ_BUF_MAX 30 -/* RTAS Userspace access */ +/** + * ppc_rtas_rmo_buf_show() - Describe RTAS-addressable region for user space. + * + * Base + size description of a range of RTAS-addressable memory set + * aside for user space to use as work area(s) for certain RTAS + * functions. User space accesses this region via /dev/mem. Apart from + * security policies, the kernel does not arbitrate or serialize + * access to this region, and user space must ensure that concurrent + * users do not interfere with each other. + */ static int ppc_rtas_rmo_buf_show(struct seq_file *m, void *v) { seq_printf(m, "%016lx %x\n", rtas_rmo_buf, RTAS_RMOBUF_MAX); -- cgit v1.2.3