diff options
| author | Fenghua Yu <fenghua.yu@intel.com> | 2022-02-08 00:02:53 +0100 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2022-02-15 11:31:43 +0100 |
| commit | 6e3133d901e89a4ba83ce7ebd8c27bbeaa9ed1f2 (patch) | |
| tree | fe10c679b2e6c8062be0f22219168b1a51760a71 /tools | |
| parent | x86/cpufeatures: Re-enable ENQCMD (diff) | |
| download | linux-6e3133d901e89a4ba83ce7ebd8c27bbeaa9ed1f2.tar.xz linux-6e3133d901e89a4ba83ce7ebd8c27bbeaa9ed1f2.zip | |
tools/objtool: Check for use of the ENQCMD instruction in the kernel
The ENQCMD instruction implicitly accesses the PASID_MSR to fill in the
pasid field of the descriptor being submitted to an accelerator. But
there is no precise (and stable across kernel changes) point at which
the PASID_MSR is updated from the value for one task to the next.
Kernel code that uses accelerators must always use the ENQCMDS instruction
which does not access the PASID_MSR.
Check for use of the ENQCMD instruction in the kernel and warn on its
usage.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220207230254.3342514-11-fenghua.yu@intel.com
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/objtool/arch/x86/decode.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index c10ef78df050..479e769ca324 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -112,7 +112,7 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec const struct elf *elf = file->elf; struct insn insn; int x86_64, ret; - unsigned char op1, op2, + unsigned char op1, op2, op3, rex = 0, rex_b = 0, rex_r = 0, rex_w = 0, rex_x = 0, modrm = 0, modrm_mod = 0, modrm_rm = 0, modrm_reg = 0, sib = 0, /* sib_scale = 0, */ sib_index = 0, sib_base = 0; @@ -139,6 +139,7 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec op1 = insn.opcode.bytes[0]; op2 = insn.opcode.bytes[1]; + op3 = insn.opcode.bytes[2]; if (insn.rex_prefix.nbytes) { rex = insn.rex_prefix.bytes[0]; @@ -491,6 +492,14 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec /* nopl/nopw */ *type = INSN_NOP; + } else if (op2 == 0x38 && op3 == 0xf8) { + if (insn.prefixes.nbytes == 1 && + insn.prefixes.bytes[0] == 0xf2) { + /* ENQCMD cannot be used in the kernel. */ + WARN("ENQCMD instruction at %s:%lx", sec->name, + offset); + } + } else if (op2 == 0xa0 || op2 == 0xa8) { /* push fs/gs */ |