| Message ID | 1483731540-8055-2-git-send-email-Liam.Howlett@Oracle.com |
|---|---|
| State | Superseded |
| Delegated to: | David Miller |
| Headers | show |
From: "Liam R. Howlett" <Liam.Howlett@Oracle.com> Date: Fri, 6 Jan 2017 14:38:59 -0500 > Send a SIGBUS to the offending process on all userspace non-resumable > traps. This prevents userspace applications from creating a kernel > panic. The siginfo will return the code BUS_ADRERR and a valid address > if possible. > > Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com> Now that the code will potentially actually continue, you _must_ check the nature of the error, and potentially retire the physical page if it is real memory in order to prevent it from being used in some other way by either userspace of kernel space and thus triggering the non-resumable error all over again. The various sun4u async fault handlers have this logic present and do the right thing, something like: if (pfn_valid(afar >> PAGE_SHIFT)) get_page(pfn_to_page(afar >> PAGE_SHIFT)); This logic prevents the page from being freed up and returned to the free page pool, even if we kill the process and thus tear down it's address space. Thank you. -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c index 496fa92..3a0c153 100644 --- a/arch/sparc/kernel/traps_64.c +++ b/arch/sparc/kernel/traps_64.c @@ -2075,6 +2075,27 @@ void sun4v_nonresum_error(struct pt_regs *regs, unsigned long offset) put_cpu(); + if (!(regs->tstate & TSTATE_PRIV)) { + /* DON'T PANIC. This error was from userspace. */ + siginfo_t info; + unsigned int insn; + + info.si_signo = SIGBUS; + info.si_code = BUS_ADRERR; + info.si_errno = 0; + info.si_trapno = 0; + info.si_addr = 0; + + if (!copy_from_user(&insn, (void __user *)regs->tpc, 4)) { + info.si_addr = (void __user *) + compute_effective_address(regs, insn, + (insn >> 25) & 0x1f); + } + + force_sig_info(SIGBUS, &info, current); + return; + } + #ifdef CONFIG_PCI /* Check for the special PCI poke sequence. */ if (pci_poke_in_progress && pci_poke_cpu == cpu) {
Send a SIGBUS to the offending process on all userspace non-resumable traps. This prevents userspace applications from creating a kernel panic. The siginfo will return the code BUS_ADRERR and a valid address if possible. Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com> --- arch/sparc/kernel/traps_64.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+)