From: Mathis Salmen mathis.salmen@matsal.de
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 mathis.salmen@matsal.de 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 palmer@rivosinc.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/riscv/kernel/signal.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
--- a/arch/riscv/kernel/signal.c +++ b/arch/riscv/kernel/signal.c @@ -16,6 +16,7 @@ #include <asm/vdso.h> #include <asm/switch_to.h> #include <asm/csr.h> +#include <asm/cacheflush.h>
extern u32 __user_rt_sigreturn[2];
@@ -178,6 +179,7 @@ static int setup_rt_frame(struct ksignal { 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))) @@ -206,7 +208,12 @@ static int setup_rt_frame(struct ksignal 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 */
/*