Messages in this thread Patch in this message | | | From | Christophe Leroy <> | Subject | [PATCH v2 06/15] powerpc/align: Don't use __get_user_instr() on kernel addresses | Date | Wed, 10 Mar 2021 17:46:45 +0000 (UTC) |
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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 <christophe.leroy@csgroup.eu> --- arch/powerpc/kernel/align.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/align.c b/arch/powerpc/kernel/align.c index c4d7b445b459..8d4c7af262e2 100644 --- a/arch/powerpc/kernel/align.c +++ b/arch/powerpc/kernel/align.c @@ -310,7 +310,11 @@ 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... */ -- 2.25.0
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