ubsan: Fix objtool UACCESS warns

clang-14 allyesconfig gives:

  vmlinux.o: warning: objtool: emulator_cmpxchg_emulated+0x705: call to __ubsan_handle_load_invalid_value() with UACCESS enabled
  vmlinux.o: warning: objtool: paging64_update_accessed_dirty_bits+0x39e: call to __ubsan_handle_load_invalid_value() with UACCESS enabled
  vmlinux.o: warning: objtool: paging32_update_accessed_dirty_bits+0x390: call to __ubsan_handle_load_invalid_value() with UACCESS enabled
  vmlinux.o: warning: objtool: ept_update_accessed_dirty_bits+0x43f: call to __ubsan_handle_load_invalid_value() with UACCESS enabled

Add the required eflags save/restore and whitelist the thing.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230112195541.906007455@infradead.org

diff --git a/lib/ubsan.c b/lib/ubsan.c
index 60c7099..4d39e0b 100644 (file)
--- a/lib/ubsan.c
+++ b/lib/ubsan.c
@@ -339,9 +339,10 @@ void __ubsan_handle_load_invalid_value(void *_data, void *val)
 {
        struct invalid_value_data *data = _data;
        char val_str[VALUE_LENGTH];
+       unsigned long ua_flags = user_access_save();
 
        if (suppress_report(&data->location))
-               return;
+               goto out;
 
        ubsan_prologue(&data->location, "invalid-load");
 
@@ -351,6 +352,8 @@ void __ubsan_handle_load_invalid_value(void *_data, void *val)
                val_str, data->type->type_name);
 
        ubsan_epilogue();
+out:
+       user_access_restore(ua_flags);
 }
 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
 

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 64954aa..9767bab 100644 (file)
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1216,6 +1216,7 @@ static const char *uaccess_safe_builtin[] = {
        "__ubsan_handle_type_mismatch",
        "__ubsan_handle_type_mismatch_v1",
        "__ubsan_handle_shift_out_of_bounds",
+       "__ubsan_handle_load_invalid_value",
        /* misc */
        "csum_partial_copy_generic",
        "copy_mc_fragile",