From 5d12b36d72bbefe7558f19294b647d0605a80de1 Mon Sep 17 00:00:00 2001 From: Mathis Salmen Date: Thu, 6 Apr 2023 12:11:31 +0200 Subject: [PATCH] riscv: add icache flush for nommu sigreturn trampoline commit 8d736482749f6d350892ef83a7a11d43cd49981e upstream. In a NOMMU kernel, sigreturn trampolines are generated on the user stack by setup_rt_frame. Currently, these trampolines are not instruction fenced, thus their visibility to ifetch is not guaranteed. This patch adds a flush_icache_range in setup_rt_frame to fix this problem. Signed-off-by: Mathis Salmen Fixes: 6bd33e1ece52 ("riscv: add nommu support") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20230406101130.82304-1-mathis.salmen@matsal.de Signed-off-by: Palmer Dabbelt Signed-off-by: Greg Kroah-Hartman --- arch/riscv/kernel/signal.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c index bfb2afa4135f..dee66c9290cc 100644 --- a/arch/riscv/kernel/signal.c +++ b/arch/riscv/kernel/signal.c @@ -19,6 +19,7 @@ #include #include #include +#include extern u32 __user_rt_sigreturn[2]; @@ -181,6 +182,7 @@ static int setup_rt_frame(struct ksignal *ksig, sigset_t *set, { struct rt_sigframe __user *frame; long err = 0; + unsigned long __maybe_unused addr; frame = get_sigframe(ksig, regs, sizeof(*frame)); if (!access_ok(frame, sizeof(*frame))) @@ -209,7 +211,12 @@ static int setup_rt_frame(struct ksignal *ksig, sigset_t *set, if (copy_to_user(&frame->sigreturn_code, __user_rt_sigreturn, sizeof(frame->sigreturn_code))) return -EFAULT; - regs->ra = (unsigned long)&frame->sigreturn_code; + + addr = (unsigned long)&frame->sigreturn_code; + /* Make sure the two instructions are pushed to icache. */ + flush_icache_range(addr, addr + sizeof(frame->sigreturn_code)); + + regs->ra = addr; #endif /* CONFIG_MMU */ /*