[PATCH 5.10 180/518] riscv: Fix fp alignment bug in perf_callchain_user()

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5.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>

[ 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@xxxxxxxxxx>
Cc: Björn Töpel <bjorn@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240708032847.2998158-2-ruanjinjie@xxxxxxxxxx
Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 arch/riscv/kernel/perf_callchain.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c
index fb02811df7143..3c0a43cb1c33e 100644
--- 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);
 }
 
-- 
2.43.0







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