bolt/test/X86/linux-static-keys.s

# REQUIRES: system-linux

## Check that BOLT correctly updates the Linux kernel static keys jump table.

# RUN: llvm-mc -filetype=obj -triple x86_64-unknown-unknown %s -o %t.o
# RUN: link_fdata %s %t.o %t.fdata
# RUN: llvm-strip --strip-unneeded %t.o
# RUN: %clang %cflags -nostdlib %t.o -o %t.exe \
# RUN:   -Wl,--image-base=0xffffffff80000000,--no-dynamic-linker,--no-eh-frame-hdr

## Verify static keys jump bindings to instructions.

# RUN: llvm-bolt %t.exe --print-normalized -o %t.out --keep-nops=0 \
# RUN:   --bolt-info=0 2>&1 | FileCheck %s

## Verify that profile is matched correctly.

# RUN: llvm-bolt %t.exe --print-normalized -o %t.out --keep-nops=0 \
# RUN:   --bolt-info=0 --data %t.fdata 2>&1 \
# RUN:   | FileCheck --check-prefix=CHECK-FDATA %s

## Verify the bindings again on the rewritten binary with nops removed.

# RUN: llvm-bolt %t.out -o %t.out.1 --print-normalized 2>&1 | FileCheck %s

# CHECK:      BOLT-INFO: Linux kernel binary detected
# CHECK:      BOLT-INFO: parsed 2 static keys jump entries

  .text
  .globl _start
  .type _start, %function
_start:
# CHECK: Binary Function "_start"
  nop
.L0:
  jmp L1
# CHECK:      jit
# CHECK-SAME: # ID: 1 {{.*}} # Likely: 1 # InitValue: 0
  nop
L1:
  .nops 5
# CHECK:      jit
# CHECK-SAME: # ID: 2 {{.*}} # Likely: 0 # InitValue: 0
  jmp .L0

## Check that a branch profile associated with a NOP is handled properly when
## dynamic branch is created.

# FDATA: 1 _start #L1# 1 _start #L2# 3 42
# CHECK-FDATA: jit {{.*}} # ID: 2
# CHECK-FDATA-NEXT: jmp
# CHECK-FDATA-NEXT: Successors: {{.*}}  (mispreds: 3, count: 42)
L2:
  nop
  .size _start, .-_start

  .globl foo
  .type foo, %function
foo:
  ret
  .size foo, .-foo


## Static keys jump table.
  .rodata
  .globl __start___jump_table
  .type __start___jump_table, %object
__start___jump_table:

  .long .L0 - .                   # Jump address
  .long L1 - .                    # Target address
  .quad fake_static_key + 1 - .   # Key address; LSB = 1 : likely

  .long L1 - .                    # Jump address
  .long L2 - .                    # Target address
  .quad fake_static_key -.        # Key address; LSB = 0 : unlikely

  .globl __stop___jump_table
  .type __stop___jump_table, %object
__stop___jump_table:

## Staic keys (we just use the label ignoring the format of the keys).
  .data
  .align 8
fake_static_key:
  .quad 0

## Linux kernel version
  .rodata
  .align 16
  .globl linux_banner
  .type  linux_banner, @object
linux_banner:
  .string  "Linux version 6.6.61\n"
  .size  linux_banner, . - linux_banner

## Fake Linux Kernel sections.
  .section __ksymtab,"a",@progbits
  .section __ksymtab_gpl,"a",@progbits