Public bug reported:
[Impact] * A kernel build can fail to boot with Oops and illegal instruction as seen at https://bugs.launchpad.net/ubuntu/+source/linux- riscv-5.11/+bug/1934548 on Unmatched board. * One cannot frace functions, used in frace setup. On RISC-V these are sbi calls to firmware from sbi.c which were not excluded for tracing. Similar functions on other arches are already excluded. * Previously we have identified one call that was racing and causing failure to boot and marked it for notrace. But the upstream solution is to disable all functions in sbi.c which was implemented in v5.12 but did not make it to stable/earlier trees. * Note that this failure to boot is racy, meaning some lucky builds of kernel always boot or always fail, as was observed on Unmatched. [Test Plan] * Kernel should boot on baremetal Unmatched, Unleashed, and qemu [Where problems could occur] * This patch disables profiling and tracing of sbi.c function calls. Previously it was possible to trace them, somewhat, either successfully in a racy manner or to cause a kernel panic. ** Affects: linux-riscv (Ubuntu) Importance: Undecided Status: New ** Affects: linux-riscv (Ubuntu Focal) Importance: Undecided Status: New ** Affects: linux-riscv (Ubuntu Hirsute) Importance: Undecided Status: New ** Package changed: linux-riscv-5.11 (Ubuntu) => linux-riscv (Ubuntu) ** Also affects: linux-riscv (Ubuntu Hirsute) Importance: Undecided Status: New ** Also affects: linux-riscv (Ubuntu Focal) Importance: Undecided Status: New -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux-riscv-5.11 in Ubuntu. https://bugs.launchpad.net/bugs/1940426 Title: Disable ftrace of sbi functions Status in linux-riscv package in Ubuntu: New Status in linux-riscv source package in Focal: New Status in linux-riscv source package in Hirsute: New Bug description: [Impact] * A kernel build can fail to boot with Oops and illegal instruction as seen at https://bugs.launchpad.net/ubuntu/+source/linux- riscv-5.11/+bug/1934548 on Unmatched board. * One cannot frace functions, used in frace setup. On RISC-V these are sbi calls to firmware from sbi.c which were not excluded for tracing. Similar functions on other arches are already excluded. * Previously we have identified one call that was racing and causing failure to boot and marked it for notrace. But the upstream solution is to disable all functions in sbi.c which was implemented in v5.12 but did not make it to stable/earlier trees. * Note that this failure to boot is racy, meaning some lucky builds of kernel always boot or always fail, as was observed on Unmatched. [Test Plan] * Kernel should boot on baremetal Unmatched, Unleashed, and qemu [Where problems could occur] * This patch disables profiling and tracing of sbi.c function calls. Previously it was possible to trace them, somewhat, either successfully in a racy manner or to cause a kernel panic. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-riscv/+bug/1940426/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
