Re: [PATCH v3 3/5] powerpc/64: Convert patch_instruction() to patch_u32()
From: Naveen N Rao <naveen@kernel.org>
Date: 2024-04-23 09:43:48
On Mon, Mar 25, 2024 at 04:53:00PM +1100, Benjamin Gray wrote:
This use of patch_instruction() is working on 32 bit data, and can fail
if the data looks like a prefixed instruction and the extra write
crosses a page boundary. Use patch_u32() to fix the write size.
Fixes: 8734b41b3efe ("powerpc/module_64: Fix livepatching for RO modules")
Link: https://lore.kernel.org/all/20230203004649.1f59dbd4@yea/ (local)
Signed-off-by: Benjamin Gray <redacted>
---
v2: * Added the fixes tag, it seems appropriate even if the subject does
mention a more robust solution being required.
patch_u64() should be more efficient, but judging from the bug report
it doesn't seem like the data is doubleword aligned.Asking again, is that still the case? It looks like at least the first fix below can be converted to patch_u64(). - Naveen
quoted hunk ↗ jump to hunk
--- arch/powerpc/kernel/module_64.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c index 7112adc597a8..e9bab599d0c2 100644 --- a/arch/powerpc/kernel/module_64.c +++ b/arch/powerpc/kernel/module_64.c@@ -651,12 +651,11 @@ static inline int create_stub(const Elf64_Shdr *sechdrs, // func_desc_t is 8 bytes if ABIv2, else 16 bytes desc = func_desc(addr); for (i = 0; i < sizeof(func_desc_t) / sizeof(u32); i++) { - if (patch_instruction(((u32 *)&entry->funcdata) + i, - ppc_inst(((u32 *)(&desc))[i]))) + if (patch_u32(((u32 *)&entry->funcdata) + i, ((u32 *)&desc)[i])) return 0; } - if (patch_instruction(&entry->magic, ppc_inst(STUB_MAGIC))) + if (patch_u32(&entry->magic, STUB_MAGIC)) return 0; return 1;-- 2.44.0