From: Björn Töpel bjorn@rivosinc.com

[ Upstream commit 7d1d19a11cfbfd8bae1d89cc010b2cc397cd0c48 ]

The XOL (execute out-of-line) buffer is used to single-step the replaced instruction(s) for uprobes. The RISC-V port was missing a proper fence.i (i$ flushing) after constructing the XOL buffer, which can result in incorrect execution of stale/broken instructions.

This was found running the BPF selftests "test_progs: uprobe_autoattach, attach_probe" on the Spacemit K1/X60, where the uprobes tests randomly blew up.

Reviewed-by: Guo Ren guoren@kernel.org Fixes: 74784081aac8 ("riscv: Add uprobes supported") Signed-off-by: Björn Töpel bjorn@rivosinc.com Link: https://lore.kernel.org/r/20250419111402.1660267-2-bjorn@kernel.org Signed-off-by: Palmer Dabbelt palmer@rivosinc.com Signed-off-by: Rahul Sharma black.hawk@163.com --- arch/riscv/kernel/probes/uprobes.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/arch/riscv/kernel/probes/uprobes.c b/arch/riscv/kernel/probes/uprobes.c index 4b3dc8beaf77..cc15f7ca6cc1 100644 --- a/arch/riscv/kernel/probes/uprobes.c +++ b/arch/riscv/kernel/probes/uprobes.c @@ -167,6 +167,7 @@ void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr, /* Initialize the slot */ void *kaddr = kmap_atomic(page); void *dst = kaddr + (vaddr & ~PAGE_MASK); + unsigned long start = (unsigned long)dst;

memcpy(dst, src, len);

@@ -176,13 +177,6 @@ void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr, *(uprobe_opcode_t *)dst = __BUG_INSN_32; }

+ flush_icache_range(start, start + len); kunmap_atomic(kaddr); - - /* - * We probably need flush_icache_user_page() but it needs vma. - * This should work on most of architectures by default. If - * architecture needs to do something different it can define - * its own version of the function. - */ - flush_dcache_page(page); }