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Signed-off-by: David Kaplan Reviewed-by: Nikolay Borisov --- arch/x86/kernel/cpu/bugs.c | 44 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 26ceb42e0cfb..8365448b3aef 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -16,6 +16,7 @@ #include #include #include +#include =20 #include #include @@ -4065,6 +4066,49 @@ void arch_cpu_reset_mitigations(void) tsa_reset_mitigation(); vmscape_reset_mitigation(); } + +static int rethunk_debug_show(struct seq_file *m, void *p) +{ + if (x86_return_thunk =3D=3D __x86_return_thunk) + seq_puts(m, "__x86_return_thunk\n"); + else if (x86_return_thunk =3D=3D retbleed_return_thunk) + seq_puts(m, "retbleed_return_thunk\n"); + else if (x86_return_thunk =3D=3D call_depth_return_thunk) + seq_puts(m, "call_depth_return_thunk\n"); + else if (x86_return_thunk =3D=3D its_return_thunk) + seq_puts(m, "its_return_thunk\n"); + else if (x86_return_thunk =3D=3D srso_alias_return_thunk) + seq_puts(m, "srso_alias_return_thunk\n"); + else if (x86_return_thunk =3D=3D srso_return_thunk) + seq_puts(m, "srso_return_thunk\n"); + else + seq_puts(m, "unknown\n"); + + return 0; +} + +static int rethunk_debug_open(struct inode *inode, struct file *file) +{ + return single_open(file, rethunk_debug_show, inode->i_private); +} + +static const struct file_operations dfs_thunk_ops =3D { + .open =3D rethunk_debug_open, + .read =3D seq_read, + .llseek =3D seq_lseek, + .release =3D single_release, +}; + +static int __init mitigations_debugfs_init(void) +{ + struct dentry *dir; + + dir =3D debugfs_create_dir("mitigations", arch_debugfs_dir); + debugfs_create_file("x86_return_thunk", 0400, dir, NULL, &dfs_thunk_ops); + + return 0; +} +late_initcall(mitigations_debugfs_init); #endif =20 void cpu_bugs_update_speculation_msrs(void) --=20 2.34.1