Hi, David! I've been looking into traps-related routines for some time, and was confused with srmmu user stack checking code. Here is the corresponding part of etrap.S file: 278 .globl tsetup_srmmu_stackchk 279 tsetup_srmmu_stackchk: 280 /* Check results of callers andcc %sp, 0x7, %g0 */ 281 bne trap_setup_user_stack_is_bolixed 282 sethi %hi(PAGE_OFFSET), %glob_tmp 283 284 cmp %glob_tmp, %sp 285 bleu,a 1f 286 lda [%g0] ASI_M_MMUREGS, %glob_tmp ! read MMU control 287 288 trap_setup_user_stack_is_bolixed: 289 /* From user/kernel into invalid window w/bad user 290 * stack. Save bad user stack, and return to caller. 291 */ 292 SAVE_BOLIXED_USER_STACK(curptr, g3) 293 restore %g0, %g0, %g0 294 295 jmpl %t_retpc + 0x8, %g0 296 mov %t_kstack, %sp 297 298 1: 299 /* Clear the fault status and turn on the no_fault bit. */ 300 or %glob_tmp, 0x2, %glob_tmp ! or in no_fault bit 301 sta %glob_tmp, [%g0] ASI_M_MMUREGS ! set it 302 303 /* Dump the registers and cross fingers. */ 304 STORE_WINDOW(sp) On the line 284 we compare user stack pointer with PAGE_OFFSET, and if it is greater than PAGE_OFFSET, then we consider user stack is still ok and continue checking. On the contrary, if %sp is small enough, bollixed stack handler is entered at once. Is it right? The same part of wof.S looks more logical - if %sp is greater than kernel base, then branch into a spwin_user_stack_is_bolixed. 398 sethi %hi(PAGE_OFFSET), %glob_tmp 399 cmp %glob_tmp, %sp 400 bleu spwin_user_stack_is_bolixed I am perplexed especially because of the fact that this part of logic has not been changed since 1999, and nevertheless Linux works well. (but trap_setup_user_stack_is_bolixed is reached in fact, I've just tested on the hardware with grmon). Linux version is 2.6.21.1. Please let me know if this is really a bug or where am I wrong else. Thanks in advance. -- Best regards, Eldar Sh. Abusalimov -- 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
