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mips: FIx clone3 implementation (BZ 31325)

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For o32 we need to setup a minimal stack frame to allow cprestore
on __thread_start_clone3 (which instruct the linker to save the
gp for PIC).  Also, there is no guarantee by kABI that $8 will be
preserved after syscall execution, so we need to save it on the
provided stack.

Checked on mipsel-linux-gnu.

Reported-by: Khem Raj <raj.khem@gmail.com>
Tested-by: Khem Raj <raj.khem@gmail.com>
This commit is contained in:
Adhemerval Zanella 2024-02-01 14:29:53 -03:00
parent e7b90e6e60
commit bbd248ac0d
1 changed files with 27 additions and 5 deletions
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32
sysdeps/unix/sysv/linux/mips/clone3.S
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@ -37,11 +37,6 @@
.text
.set nomips16
#if _MIPS_SIM == _ABIO32
# define EXTRA_LOCALS 1
#else
# define EXTRA_LOCALS 0
#endif
#define FRAMESZ ((NARGSAVE*SZREG)+ALSZ)&ALMASK
GPOFF= FRAMESZ-(1*SZREG)
NESTED(__clone3, SZREG, sp)
@ -68,8 +63,31 @@ NESTED(__clone3, SZREG, sp)
beqz a0, L(error) /* No NULL cl_args pointer. */
beqz a2, L(error) /* No NULL function pointer. */
#if _MIPS_SIM == _ABIO32
/* Both stack and stack_size on clone_args are defined as uint64_t, and
there is no need to handle values larger than to 32 bits for o32. */
# if __BYTE_ORDER == __BIG_ENDIAN
# define CL_STACKPOINTER_OFFSET 44
# define CL_STACKSIZE_OFFSET 52
# else
# define CL_STACKPOINTER_OFFSET 40
# define CL_STACKSIZE_OFFSET 48
# endif
/* For o32 we need to setup a minimal stack frame to allow cprestore
on __thread_start_clone3. Also there is no guarantee by kABI that
$8 will be preserved after syscall execution (so we need to save it
on the provided stack). */
lw t0, CL_STACKPOINTER_OFFSET(a0) /* Load the stack pointer. */
lw t1, CL_STACKSIZE_OFFSET(a0) /* Load the stack_size. */
addiu t1, -32 /* Update the stack size. */
addu t2, t1, t0 /* Calculate the thread stack. */
sw a3, 0(t2) /* Save argument pointer. */
sw t1, CL_STACKSIZE_OFFSET(a0) /* Save the new stack size. */
#else
move $8, a3 /* a3 is set to 0/1 for syscall success/error
while a4/$8 is returned unmodified. */
#endif
/* Do the system call, the kernel expects:
v0: system call number
@ -125,7 +143,11 @@ L(thread_start_clone3):
/* Restore the arg for user's function. */
move t9, a2 /* Function pointer. */
#if _MIPS_SIM == _ABIO32
PTR_L a0, 0(sp)
#else
move a0, $8 /* Argument pointer. */
#endif
/* Call the user's function. */
jal t9