| Message ID | 20231016050147.115686-3-bgray@linux.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Add generic data patching functions | expand |
On Mon, Oct 16, 2023 at 04:01:46PM +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/ > Signed-off-by: Benjamin Gray <bgray@linux.ibm.com> > > --- > > 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. That doesn't look to be the case anymore due to commits 77e69ee7ce07 ("powerpc/64: modules support building with PCREL addresing") and 7e3a68be42e1 ("powerpc/64: vmlinux support building with PCREL addresing") - Naveen
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;
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/ Signed-off-by: Benjamin Gray <bgray@linux.ibm.com> --- 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. --- arch/powerpc/kernel/module_64.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)