From 111631b5e9dae764754657aad00bd6cd1a805d0d Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Wed, 10 Mar 2021 17:46:45 +0000 Subject: powerpc/align: Don't use __get_user_instr() on kernel addresses In the old days, when we didn't have kernel userspace access protection and had set_fs(), it was wise to use __get_user() and friends to read kernel memory. Nowadays, get_user() is granting userspace access and is exclusively for userspace access. In alignment exception handler, use probe_kernel_read_inst() instead of __get_user_instr() for reading instructions in kernel. This will allow to remove the is_kernel_addr() check in __get/put_user() in a following patch. Signed-off-by: Christophe Leroy Reviewed-by: Daniel Axtens Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/d9ecbce00178484e66ca7adec2ff210058037704.1615398265.git.christophe.leroy@csgroup.eu --- arch/powerpc/kernel/align.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/align.c b/arch/powerpc/kernel/align.c index f362c99213be..a97d5f1a3905 100644 --- a/arch/powerpc/kernel/align.c +++ b/arch/powerpc/kernel/align.c @@ -310,7 +310,12 @@ int fix_alignment(struct pt_regs *regs) */ CHECK_FULL_REGS(regs); - if (unlikely(__get_user_instr(instr, (void __user *)regs->nip))) + if (is_kernel_addr(regs->nip)) + r = probe_kernel_read_inst(&instr, (void *)regs->nip); + else + r = __get_user_instr(instr, (void __user *)regs->nip); + + if (unlikely(r)) return -EFAULT; if ((regs->msr & MSR_LE) != (MSR_KERNEL & MSR_LE)) { /* We don't handle PPC little-endian any more... */ -- cgit