[PATCH v2 2/2] test: unit test for longjmp

[Heinrich Schuchardt]

On 22.03.21 14:30, Sean Anderson wrote:
>
> On 3/22/21 9:23 AM, Sean Anderson wrote:
>>
>> On 3/22/21 7:02 AM, Heinrich Schuchardt wrote:
>>> Provide a unit test for the longjmp() library function
>>>
>>> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
>>> ---
>>> v2:
>>>     no change
>>> ---
>>>   test/lib/Makefile  |  1 +
>>>   test/lib/longjmp.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>>>   2 files changed, 45 insertions(+)
>>>   create mode 100644 test/lib/longjmp.c
>>>
>>> diff --git a/test/lib/Makefile b/test/lib/Makefile
>>> index 97c11e35a8..a30f615aa9 100644
>>> --- a/test/lib/Makefile
>>> +++ b/test/lib/Makefile
>>> @@ -7,6 +7,7 @@ obj-$(CONFIG_EFI_LOADER) += efi_device_path.o
>>>   obj-$(CONFIG_EFI_SECURE_BOOT) += efi_image_region.o
>>>   obj-y += hexdump.o
>>>   obj-y += lmb.o
>>> +obj-y += longjmp.o
>>>   obj-$(CONFIG_CONSOLE_RECORD) += test_print.o
>>>   obj-$(CONFIG_SSCANF) += sscanf.o
>>>   obj-y += string.o
>>> diff --git a/test/lib/longjmp.c b/test/lib/longjmp.c
>>> new file mode 100644
>>> index 0000000000..7571540ffc
>>> --- /dev/null
>>> +++ b/test/lib/longjmp.c
>>> @@ -0,0 +1,44 @@
>>> +// SPDX-License-Identifier: GPL-2.0+
>>> +/*
>>> + * Test setjmp(), longjmp()
>>> + *
>>> + * Copyright (c) 2021, Heinrich Schuchardt <xypron.glpk at gmx.de>
>>> + */
>>> +
>>> +#include <common.h>
>>> +#include <test/lib.h>
>>> +#include <test/test.h>
>>> +#include <test/ut.h>
>>> +#include <asm/setjmp.h>
>>> +
>>> +/**
>>> + * test_longjmp_ret() - get longjmp() return value
>>> + *
>>> + * @i:        value passed to longjmp()
>>> + * Return:    value returned by longjmp()
>>> + */
>>> +int test_longjmp_ret(int i)
>>> +{
>>> +    jmp_buf env;
>>> +    int ret;
>>> +
>>> +    ret = setjmp(env);
>>> +    if (ret)
>>> +        return ret;
>>> +    longjmp(env, i);
>>> +    /* We should not arrive here */
>>> +    return 0x1000;
>>> +}
>>> +
>>> +static int lib_test_longjmp(struct unit_test_state *uts)
>>> +{
>>> +    int i;
>>> +
>>> +    for (i = -3; i < 0; ++i)
>>> +        ut_asserteq(i, test_longjmp_ret(i));
>>> +    ut_asserteq(1, test_longjmp_ret(0));
>>> +    for (i = 1; i < 4; ++i)
>>> +        ut_asserteq(i, test_longjmp_ret(i));
>>> +    return 0;
>>> +}
>>> +LIB_TEST(lib_test_longjmp, 0);
>>> -- 
>>> 2.30.2
>>>
>>
>> Reviewed-by: Sean Anderson <seanga2 at gmail.com>
>> Tested-by: Sean Anderson <seanga2 at gmail.com>
>>
>> Though I would like to test that variables are set correctly e.g. by
>> doing
>>
>> int test_longjmp_ret(int i)
>> {
>>      jmp_buf env;
>>      int ret;
>>
>>      ret = setjmp(env);
>>      if (ret)
>>          return ret;
>>      ret = 0x1000;
>>      longjmp(env, i);
>>      /* We should not arrive here */
>>      return ret;
>> }
>>
>> --Sean
>
> err, rather by doing
>
> int test_longjmp_ret(int i)
> {
>      jmp_buf env;
>      int ret;
>      int foo = i;
>
>      ret = setjmp(env);
>      if (ret)
>          return foo;
>      foo = 0x1000;
>      longjmp(env, i);
>      /* We should not arrive here */
>      return foo;
> }
>
> or something else which demonstrates that variables get reset to their
> earlier values.
>
> --Sean

Hello Sean,

thank you for reviewing.

Would the following make sense to you to check that the stack pointer is
correctly restored?


struct test_jmp_buf {
        jmp_buf env;
        int val;
};

/**
 * test_longjmp() - test longjmp function
 *
 * @i is passed to longjmp.
 * @i << 8 is set in the environment structure.
 *
 * @env:        environment
 * @i:          value passed to longjmp()
 */
static void noinline test_longjmp(struct test_jmp_buf *env, int i)
{
        env->val = i << 8;
        longjmp(env->env, i);
}

/**
 * test_setjmp() - test setjmp function
 *
 * setjmp() will return the value @i passed to longjmp() if @i is non-zero.
 * For @i == 0 we expect return value 1.
 *
 * @i << 8 will be set by test_longjmp in the environment structure.
 * This value can be used to check that the stack frame is restored.
 *
 * We return the XORed values to allow simply check both at once.
 *
 * @i:          value passed to longjmp()
 * Return:      values return byby longjmp()
 */
static int test_setjmp(int i)
{
        struct test_jmp_buf env;
        int ret;

        env.val = -1;
        ret = setjmp(env.env);
        if (ret)
                return ret ^ env.val;
        test_longjmp(&env, i);
        /* We should not arrive here */
        return 0x1000;
}

Best regards

Heinrich