On Thu 2025-03-20 10:15:57, Song Liu wrote: > There are recent efforts to enable livepatch for arm64, with sframe [1] or > without sframe [2]. This set tries to enable livepatch without sframe. Some > of the code, however, are from [1]. > > Although the sframe implementation is more promising in longer term, it > suffers from the following issues: > > 1. sframe is not yet supported in llvm; > 2. There is still bug in binutil [3], so that we cannot yet use sframe > with gcc; > 3. sframe unwinder hasn't been fully verified in the kernel. > > On the other hand, arm64 processors have become more and more important in > the data center world. Therefore, it is getting critical to support > livepatching of arm64 kernels. > > With recent change in arm64 unwinder [4], it is possible to reliably > livepatch arm64 kernels without sframe. This is because we do not need > arch_stack_walk_reliable() to get reliable stack trace in all scenarios. > Instead, we only need arch_stack_walk_reliable() to detect when the > stack trace is not reliable, then the livepatch logic can retry the patch > transition at a later time. > > Given the increasing need of livepatching, and relatively long time before > sframe is fully ready (for both gcc and clang), we would like to enable > livepatch without sframe. > > Thanks! > > [1] > https://lore.kernel.org/live-patching/20250127213310.2496133-1-wn...@google.com/ > [2] > https://lore.kernel.org/live-patching/20250129232936.1795412-1-s...@kernel.org/ > [3] https://sourceware.org/bugzilla/show_bug.cgi?id=32589 > [4] > https://lore.kernel.org/linux-arm-kernel/20241017092538.1859841-1-mark.rutl...@arm.com/ > > Changes v2 => v3: > 1. Remove a redundant check for -ENOENT. (Josh Poimboeuf) > 2. Add Tested-by and Acked-by on v1. (I forgot to add them in v2.)
The approach and both patches look reasonable: Reviewed-by: Petr Mladek <pmla...@suse.com> Is anyone, Arm people, Mark, against pushing this into linux-next, please? Best Regards, Petr
