Hi Segher,
Following is more information that I can collect. Please let me know if you need anything else.
Thank you very much for your help.
Regards,
Hon
=====================================================================
+ this is part of the content of cdev.c, from which the error happened
...
...
struct static_key_false test;
int qdma_cdev_init(void) {
if (static_branch_unlikely(&test)) {
printk("test...\n");
}
return 0;
}
void qdma_cdev_cleanup(void) {
}
...
+ static_branch_unlikely is defined as followed from /lib/modules/`uname -r`/build/include/linux/jump_label.h :
#define static_branch_unlikely(x) \
({ \
bool branch; \
if (__builtin_types_compatible_p(typeof(*x), struct static_key_true)) \
branch = arch_static_branch_jump(&(x)->key, false); \
else if (__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
branch = arch_static_branch(&(x)->key, false); \
else \
branch = ____wrong_branch_error(); \
unlikely(branch); \
})
+ the error is related to arch_static_branch_jump() which is defined from /lib/modules/`uname -r`/build/arch/x86/include/asm/jump_label.h as followed:
static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
{
asm_volatile_goto("1:"
".byte " __stringify(STATIC_KEY_INIT_NOP) "\n\t"
".pushsection __jump_table, \"aw\" \n\t"
_ASM_ALIGN "\n\t"
_ASM_PTR "1b, %l[l_yes], %c0 + %c1 \n\t"
".popsection \n\t"
: : "i" (key), "i" (branch) : : l_yes);
return false;
l_yes:
return true;
}
+ The code compiled successfully in kernel mode with followed command:
+ make V=1 clean
+ make V=1
+ The code failed to compile when I try to compile into user space mode with the followed command:
+ make -f Makefile.user clean
+ make -f Makefile.user
+ Note that the difference between gcc command line between the 2 modes are:
+ kernel: .... -fno-PIE ... -mcmodel=kernel ...
+ user space: .... -fPIC ... < removed > ...
+ Another interesting note is:
+ if I remove -fPIC from user space gcc command, then the code compile successfully. However -fPIC is the must for my project.
-----Original Message-----
From: Segher Boessenkool <segher@xxxxxxxxxxxxxxxxxxx>
Sent: Friday, September 10, 2021 11:36 AM
To: HON LUU <hon@xxxxxxxxxxxxxxxx>
Cc: gcc-help@xxxxxxxxxxx
Subject: Re: gcc question
On Fri, Sep 10, 2021 at 05:58:07PM +0000, HON LUU wrote:
> Hi Segher,
>
> I wonder if you have any issues to reproduce the problem.
> Attached is the tar ball of stand alone module, which duplicate the issue.
> There is a README file, should be straightforward to duplicate the issue.
> You need to show the full code of the asm_volatile_goto, and the declarations of everything used in its operands, for us to get a handle on what is going on here. Bonus points if you manage to make a stand- alone compilable testcase that shows the problem.
If you write up a good email with all the necessary info, you will get an answer (and a good answer!) much quicker. I do not particularly feel like doing all the work here. Sorry.
Segher
