On Mon, 2018-10-22 at 21:16:26 UTC, Breno Leitao wrote: > Test ptrace-tm-spd-gpr fails on current kernel (4.19) due to a segmentation > fault that happens on the child process prior to setting cptr[2] = 1. This > causes the parent process to wait forever at 'while (!pptr[2])' and the test to > be killed by the test harness framework by timeout, thus, failing. > > The segmentation fault happens because of a inline assembly being > generated as: > > 0x10000355c <tm_spd_gpr+492> lfs f0, 0(0) > > This is reading memory position 0x0 and causing the segmentation fault. > > This code is being generated by ASM_LOAD_FPR_SINGLE_PRECISION(flt_4), where > flt_4 is passed to the inline assembly block as: > > [flt_4] "r" (&d) > > Since the inline assembly 'r' constraint means any GPR, gpr0 is being > chosen, thus causing this issue when issuing a Load Floating-Point Single > instruction. > > This patch simply changes the constraint to 'b', which specify that this > register will be used as base, and r0 is not allowed to be used, avoiding > this issue. > > Other than that, removing flt_2 register from the input operands, since it > is not used by the inline assembly code at all. > > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx> > Acked-by: Segher Boessenkool <segher@xxxxxxxxxxxxxxxxxxx> Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/48dc0ef19044bfb69193302fbe3a83 cheers
