[PATCH 6.6.y 00/27] ftrace/sorttable: Fix ftrace symbol table corruption with CONFIG_X86_KERNEL_IBT=y

[Andrey Grodzovsky <andrey.grodzovsky@crowdstrike.com>]

This series backports the upstream fix for ftrace symbol table
corruption on kernels with CONFIG_X86_KERNEL_IBT=y. Weak overridden
functions corrupt the ftrace symbol table at boot, causing
non-deterministic hook attachment failures across all ftrace consumers
— most visibly fentry/trampoline-based hooks, but affecting any code
that relies on ftrace symbol lookups.

The fix was merged to mainline in Linux 6.15 via:
  https://lore.kernel.org/all/20250218195918.255228630@goodmis.org/

The original backport request and bug description sent to stable:
  https://lore.kernel.org/stable/CAOu3gNibeo3ov09CYpmzuqewB0EOsajB3hPU9pQmb_zoAUraHg@mail.gmail.com/

Red Hat independently backported this same set of patches to their
RHEL 10 kernel (6.12). Their work is at:
  https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-10/-/merge_requests/2689

The 27 patches are organized in four groups:
  - Patches 01-14: sorttable.c rewrite (prereq, merged 6.14)
  - Patch  15:     function pointer struct cleanup (prereq, merged 6.14)
  - Patches 16-21: the core IBT fix series (merged 6.15)
  - Patches 22-27: post-merge correctness fixes for arm64 and s390

All patches applied cleanly to 6.6.y (at 6.6.142). Tested on x86_64
with CONFIG_X86_KERNEL_IBT=y:

  grep __ftrace_invalid_address___ \
    /sys/kernel/tracing/available_filter_functions | wc -l
  Before: 562   After: 0

Direct test (bpftrace kprobe vs fentry on put_task_struct_rcu_user):
  Unpatched: fentry=0, kprobe=46 (silent failure confirmed)
  Patched:   fentry=46, kprobe=46 (fixed)

ftrace kernel selftests (tools/testing/selftests/ftrace):
  119 passed, 0 regressions introduced (2 pre-existing failures
  unrelated to this series).

Guenter Roeck (1):
  ftrace: Do not over-allocate ftrace memory

Steven Rostedt (25):
  scripts/sorttable: Remove unused macro defines
  scripts/sorttable: Remove unused write functions
  scripts/sorttable: Remove unneeded Elf_Rel
  scripts/sorttable: Have the ORC code use the _r() functions to read
  scripts/sorttable: Make compare_extable() into two functions
  scripts/sorttable: Convert Elf_Ehdr to union
  scripts/sorttable: Replace Elf_Shdr Macro with a union
  scripts/sorttable: Convert Elf_Sym MACRO over to a union
  scripts/sorttable: Add helper functions for Elf_Ehdr
  scripts/sorttable: Add helper functions for Elf_Shdr
  scripts/sorttable: Add helper functions for Elf_Sym
  scripts/sorttable: Use uint64_t for mcount sorting
  scripts/sorttable: Move code from sorttable.h into sorttable.c
  scripts/sorttable: Get start/stop_mcount_loc from ELF file directly
  scripts/sorttable: Use a structure of function pointers for elf
    helpers
  arm64: scripts/sorttable: Implement sorting mcount_loc at boot for
    arm64
  scripts/sorttable: Have mcount rela sort use direct values
  scripts/sorttable: Always use an array for the mcount_loc sorting
  scripts/sorttable: Zero out weak functions in mcount_loc table
  ftrace: Update the mcount_loc check of skipped entries
  ftrace: Have ftrace pages output reflect freed pages
  ftrace: Test mcount_loc addr before calling ftrace_call_addr()
  ftrace: Check against is_kernel_text() instead of kaslr_offset()
  scripts/sorttable: Use normal sort if theres no relocs in the mcount
    section
  scripts/sorttable: Allow matches to functions before function entry

Vasily Gorbik (1):
  scripts/sorttable: Fix endianness handling in build-time mcount sort

 arch/arm64/Kconfig      |    1 +
 kernel/trace/ftrace.c   |   68 ++-
 scripts/link-vmlinux.sh |    4 +-
 scripts/sorttable.c     | 1119 +++++++++++++++++++++++++++++++++++++--
 scripts/sorttable.h     |  500 -----------------
 5 files changed, 1133 insertions(+), 559 deletions(-)
 delete mode 100644 scripts/sorttable.h

-- 
2.34.1