diff options
| -rw-r--r-- | usr/src/uts/intel/kdi/kdi_asm.s | 64 | ||||
| -rw-r--r-- | usr/src/uts/intel/kdi/kdi_idt.c | 24 |
2 files changed, 60 insertions, 28 deletions
diff --git a/usr/src/uts/intel/kdi/kdi_asm.s b/usr/src/uts/intel/kdi/kdi_asm.s index 5180dbb1b2..edfbea10c7 100644 --- a/usr/src/uts/intel/kdi/kdi_asm.s +++ b/usr/src/uts/intel/kdi/kdi_asm.s @@ -452,8 +452,8 @@ pushq %rdi call kdi_trap_pass - cmpq $1, %rax - je kdi_pass_to_kernel + testq %rax, %rax + jnz kdi_pass_to_kernel popq %rax /* cpusave in %rax */ SAVE_IDTGDT @@ -569,17 +569,9 @@ /*NOTREACHED*/ SET_SIZE(kdi_resume) - ENTRY_NP(kdi_pass_to_kernel) - - popq %rdi /* cpusave */ - - movq $KDI_CPU_STATE_NONE, KRS_CPU_STATE(%rdi) /* - * Find the trap and vector off the right kernel handler. The trap - * handler will expect the stack to be in trap order, with %rip being - * the last entry, so we'll need to restore all our regs. On i86xpv - * we'll need to compensate for XPV_TRAP_POP. + * We took a trap that should be handled by the kernel, not KMDB. * * We're hard-coding the three cases where KMDB has installed permanent * handlers, since after we KDI_RESTORE_REGS(), we don't have registers @@ -587,15 +579,53 @@ * through here at the same time. * * Note that we handle T_DBGENTR since userspace might have tried it. + * + * The trap handler will expect the stack to be in trap order, with %rip + * being the last entry, so we'll need to restore all our regs. On + * i86xpv we'll need to compensate for XPV_TRAP_POP. + * + * %rax on entry is either 1 or 2, which is from kdi_trap_pass(). + * kdi_cmnint stashed the original %cr3 into KDIREG_CR3, then (probably) + * switched us to the CPU's kf_kernel_cr3. But we're about to call, for + * example: + * + * dbgtrap->trap()->tr_iret_kernel + * + * which, unlike, tr_iret_kdi, doesn't restore the original %cr3, so + * we'll do so here if needed. + * + * This isn't just a matter of tidiness: for example, consider: + * + * hat_switch(oldhat=kas.a_hat, newhat=prochat) + * setcr3() + * reset_kpti() + * *brktrap* due to fbt on reset_kpti:entry + * + * Here, we have the new hat's %cr3, but we haven't yet updated + * kf_kernel_cr3 (so its currently kas's). So if we don't restore here, + * we'll stay on kas's cr3 value on returning from the trap: not good if + * we fault on a userspace address. */ + ENTRY_NP(kdi_pass_to_kernel) + + popq %rdi /* cpusave */ + movq $KDI_CPU_STATE_NONE, KRS_CPU_STATE(%rdi) movq KRS_GREGS(%rdi), %rsp + + cmpq $2, %rax + jne no_restore_cr3 + movq REG_OFF(KDIREG_CR3)(%rsp), %r11 + movq %r11, %cr3 + +no_restore_cr3: movq REG_OFF(KDIREG_TRAPNO)(%rsp), %rdi + cmpq $T_SGLSTP, %rdi - je 1f + je kdi_pass_dbgtrap cmpq $T_BPTFLT, %rdi - je 2f + je kdi_pass_brktrap cmpq $T_DBGENTR, %rdi - je 3f + je kdi_pass_invaltrap /* * Hmm, unknown handler. Somebody forgot to update this when they * added a new trap interposition... try to drop back into kmdb. @@ -609,13 +639,13 @@ XPV_TRAP_PUSH; \ jmp %cs:name -1: +kdi_pass_dbgtrap: CALL_TRAP_HANDLER(dbgtrap) /*NOTREACHED*/ -2: +kdi_pass_brktrap: CALL_TRAP_HANDLER(brktrap) /*NOTREACHED*/ -3: +kdi_pass_invaltrap: CALL_TRAP_HANDLER(invaltrap) /*NOTREACHED*/ diff --git a/usr/src/uts/intel/kdi/kdi_idt.c b/usr/src/uts/intel/kdi/kdi_idt.c index d801588954..6ea4681bce 100644 --- a/usr/src/uts/intel/kdi/kdi_idt.c +++ b/usr/src/uts/intel/kdi/kdi_idt.c @@ -164,8 +164,8 @@ struct idt_description { { T_GPFLT, 0, kdi_traperr13, NULL }, { T_PGFLT, 0, kdi_traperr14, NULL }, { 15, 0, kdi_invaltrap, NULL }, - { T_EXTERRFLT, 0, kdi_trap16, NULL }, - { T_ALIGNMENT, 0, kdi_traperr17, NULL }, + { T_EXTERRFLT, 0, kdi_trap16, NULL }, + { T_ALIGNMENT, 0, kdi_traperr17, NULL }, { T_MCE, 0, kdi_trap18, NULL }, { T_SIMDFPE, 0, kdi_trap19, NULL }, { T_DBGENTR, 0, kdi_trap20, NULL }, @@ -366,14 +366,16 @@ kdi_deactivate(void) } /* - * We receive all breakpoints and single step traps. Some of them, - * including those from userland and those induced by DTrace providers, - * are intended for the kernel, and must be processed there. We adopt - * this ours-until-proven-otherwise position due to the painful - * consequences of sending the kernel an unexpected breakpoint or - * single step. Unless someone can prove to us that the kernel is - * prepared to handle the trap, we'll assume there's a problem and will - * give the user a chance to debug it. + * We receive all breakpoints and single step traps. Some of them, including + * those from userland and those induced by DTrace providers, are intended for + * the kernel, and must be processed there. We adopt this + * ours-until-proven-otherwise position due to the painful consequences of + * sending the kernel an unexpected breakpoint or single step. Unless someone + * can prove to us that the kernel is prepared to handle the trap, we'll assume + * there's a problem and will give the user a chance to debug it. + * + * If we return 2, then the calling code should restore the trap-time %cr3: that + * is, it really is a kernel-originated trap. */ int kdi_trap_pass(kdi_cpusave_t *cpusave) @@ -390,7 +392,7 @@ kdi_trap_pass(kdi_cpusave_t *cpusave) if (tt == T_BPTFLT && kdi_dtrace_get_state() == KDI_DTSTATE_DTRACE_ACTIVE) - return (1); + return (2); /* * See the comments in the kernel's T_SGLSTP handler for why we need to |