From: Jurij Smakov <jurij@xxxxxxxxx> Date: Sat, 8 Oct 2011 13:55:35 +0100 > On Sat, Oct 08, 2011 at 02:43:55AM -0400, David Miller wrote: >> @@ -67,15 +67,13 @@ LOC(thread): >> #ifdef PTR_DEMANGLE >> ld ENV(g1,JB_PC), %g5 /* Set return PC. */ >> ld ENV(g1,JB_SP), %g1 /* Set saved SP on restore below. */ >> - PTR_DEMANGLE2 (%o7, %g5, %g4) >> + PTR_DEMANGLE2 (%i7, %g5, %g4) >> PTR_DEMANGLE2 (%fp, %g1, %g4) >> #else >> - ld ENV(g1,JB_PC), %o7 /* Set return PC. */ >> + ld ENV(g1,JB_PC), %i7 /* Set return PC. */ >> ld ENV(g1,JB_SP), %fp /* Set saved SP on restore below. */ >> #endif >> - sub %fp, 64, %sp /* Allocate a register frame. */ >> - st %g3, RW_FP /* Set saved FP on restore below. */ >> - retl >> + jmp %i7 + 8 >> restore %g2, 0, %o0 /* Restore values from above register frame. */ > > I don't really see anything in the code which would ensure that after > we execute this restore, fp is going to be set to target fp value > (available as ENV(g1,JB_FP) or g3. It might be the responsibility of > the unwinding part, but then it would not explain why such code was > explicitly present in the old version. Because the restore traps, causing a window fill, and that trap handler will load up the register window at JB_SP, inside of which JB_FP is contained. The only reason we store JB_FP is for the implementation the optimized longjmp loop. -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
