Continuing the drip-feed of the exception handling support, on top of the current tip/x86/asm branch. This adds output to the serial port configured by earlyprintk, reduces the window during which exceptions can't be handled during the transition from kernel to relocate_kernel environment, and adds a kselftest for the kexec-jump and exception handling.
v9: • Rebase on top of partial merge into tip/x86/asm (commit 0717b1392dc7). • Add kselftest. • Update to cope with static_call() usage in earlyprintk. • Drop the attempt at adding CFI support for relocate_kernel(). v8: https://lore.kernel.org/all/[email protected]/ • Fix UNRET objtool warning in exc_handler. • Clean up magic numbers in stack frame for exc_handler. • Fix i386 build error due to making the debug support unconditional. • The int3 is still a [DO NOT APPLY] hack for later, and I plan to deal with that with a userspace test case based on http://david.woodhou.se/loadret.c which will exercise kexec-jump at the same time. v7: https://lore.kernel.org/kexec/[email protected]/ • Drop CONFIG_KEXEC_DEBUG and make it all unconditional in order to "throw regressions back into the face of whoever manages to introduce them" (Ingo, https://lore.kernel.org/kexec/[email protected]/) • Move IDT invalidation into relocate_kernel() itself. v6: https://lore.kernel.org/kexec/[email protected]/ • Rebase onto already-merged fixes in tip/x86/boot. • Move CONFIG_KEXEC_DEBUG to generic kernel/Kconfig.kexec as Bartosz is working on an Arm64 version. v5: https://lore.kernel.org/kexec/[email protected]/T/ • Drop [RFC]. • Drop _PAGE_NOPTISHADOW fix, which Ingo already took into tip/x86/urgent. • Add memory-mapped serial port support (32-bit MMIO spacing only). v4 (RFC): https://lore.kernel.org/kexec/[email protected]/T/ • Add _PAGE_NOPTISHADOW fix for the identmap code. • Drop explicit map of control page, which was masking the identmap bug. v3 (RFC): https://lore.kernel.org/kexec/[email protected]/T/ • Add CONFIG_KEXEC_DEBUG option and use earlyprintk config. • Allocate PGD separately from control page. • Explicitly map control page into identmap. V2 (RFC): https://lore.kernel.org/kexec/[email protected]/T/ • Introduce linker script, start to clean up data access. V1 (RFC): https://lore.kernel.org/kexec/[email protected]/T/ • Initial proof-of-concept hacks. David Woodhouse (4): x86/kexec: Add 8250 serial port output x86/kexec: Add 8250 MMIO serial port output x86/kexec: Invalidate GDT/IDT from relocate_kernel() instead of earlier selftests/kexec: Add x86_64 selftest for kexec-jump and exception handling arch/x86/include/asm/kexec.h | 2 + arch/x86/kernel/early_printk.c | 9 +++ arch/x86/kernel/machine_kexec_64.c | 27 ++++++--- arch/x86/kernel/relocate_kernel_64.S | 70 ++++++++++++++++++++--- tools/testing/selftests/kexec/Makefile | 7 +++ tools/testing/selftests/kexec/test_kexec_jump.c | 72 ++++++++++++++++++++++++ tools/testing/selftests/kexec/test_kexec_jump.sh | 42 ++++++++++++++ 7 files changed, 213 insertions(+), 16 deletions(-)
