riscv: Fix fp alignment bug in perf_callchain_user()

[ Upstream commit 22ab08955ea13be04a8efd20cc30890e0afaa49c ]

The standard RISC-V calling convention said:
	"The stack grows downward and the stack pointer is always
	kept 16-byte aligned".

So perf_callchain_user() should check whether 16-byte aligned for fp.

Link: https://riscv.org/wp-content/uploads/2015/01/riscv-calling.pdf
Fixes: dbeb90b0c1eb ("riscv: Add perf callchain support")
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Cc: Björn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/r/20240708032847.2998158-2-ruanjinjie@huawei.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c
index fb02811df71434ce30f2db7dbcf80a49f1bf9c64..3c0a43cb1c33ee497f7ef7e9e6844f2bc83ecad8 100644 (file)
--- a/arch/riscv/kernel/perf_callchain.c
+++ b/arch/riscv/kernel/perf_callchain.c
@@ -71,7 +71,7 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
        perf_callchain_store(entry, regs->epc);
 
        fp = user_backtrace(entry, fp, regs->ra);
-       while (fp && !(fp & 0x3) && entry->nr < entry->max_stack)
+       while (fp && !(fp & 0x7) && entry->nr < entry->max_stack)
                fp = user_backtrace(entry, fp, 0);
 }