diff options
| -rw-r--r-- | arch/arm64/include/asm/exception.h | 2 | ||||
| -rw-r--r-- | arch/arm64/kernel/debug-monitors.c | 73 | ||||
| -rw-r--r-- | arch/arm64/kernel/entry-common.c | 43 | ||||
| -rw-r--r-- | arch/arm64/kernel/hw_breakpoint.c | 2 |
4 files changed, 73 insertions, 47 deletions
diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h index 8ec4e0ff49b7..c8e7c61b8ac4 100644 --- a/arch/arm64/include/asm/exception.h +++ b/arch/arm64/include/asm/exception.h @@ -66,6 +66,8 @@ void do_breakpoint(unsigned long esr, struct pt_regs *regs); #else static inline void do_breakpoint(unsigned long esr, struct pt_regs *regs) {} #endif /* CONFIG_HAVE_HW_BREAKPOINT */ +void do_el0_softstep(unsigned long esr, struct pt_regs *regs); +void do_el1_softstep(unsigned long esr, struct pt_regs *regs); void do_fpsimd_acc(unsigned long esr, struct pt_regs *regs); void do_sve_acc(unsigned long esr, struct pt_regs *regs); void do_sme_acc(unsigned long esr, struct pt_regs *regs); diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c index 89264d1a9d65..cb50d1f59798 100644 --- a/arch/arm64/kernel/debug-monitors.c +++ b/arch/arm64/kernel/debug-monitors.c @@ -21,6 +21,7 @@ #include <asm/cputype.h> #include <asm/daifflags.h> #include <asm/debug-monitors.h> +#include <asm/exception.h> #include <asm/kgdb.h> #include <asm/kprobes.h> #include <asm/system_misc.h> @@ -159,21 +160,6 @@ NOKPROBE_SYMBOL(clear_user_regs_spsr_ss); #define set_regs_spsr_ss(r) set_user_regs_spsr_ss(&(r)->user_regs) #define clear_regs_spsr_ss(r) clear_user_regs_spsr_ss(&(r)->user_regs) -/* - * Call single step handlers - * There is no Syndrome info to check for determining the handler. - * However, there is only one possible handler for user and kernel modes, so - * check and call the appropriate one. - */ -static int call_step_hook(struct pt_regs *regs, unsigned long esr) -{ - if (user_mode(regs)) - return uprobe_single_step_handler(regs, esr); - - return kgdb_single_step_handler(regs, esr); -} -NOKPROBE_SYMBOL(call_step_hook); - static void send_user_sigtrap(int si_code) { struct pt_regs *regs = current_pt_regs(); @@ -188,41 +174,38 @@ static void send_user_sigtrap(int si_code) "User debug trap"); } -static int single_step_handler(unsigned long unused, unsigned long esr, - struct pt_regs *regs) +/* + * We have already unmasked interrupts and enabled preemption + * when calling do_el0_softstep() from entry-common.c. + */ +void do_el0_softstep(unsigned long esr, struct pt_regs *regs) { + if (uprobe_single_step_handler(regs, esr) == DBG_HOOK_HANDLED) + return; + + send_user_sigtrap(TRAP_TRACE); /* - * If we are stepping a pending breakpoint, call the hw_breakpoint - * handler first. + * ptrace will disable single step unless explicitly + * asked to re-enable it. For other clients, it makes + * sense to leave it enabled (i.e. rewind the controls + * to the active-not-pending state). */ - if (try_step_suspended_breakpoints(regs)) - return 0; - - if (call_step_hook(regs, esr) == DBG_HOOK_HANDLED) - return 0; + user_rewind_single_step(current); +} - if (user_mode(regs)) { - send_user_sigtrap(TRAP_TRACE); - - /* - * ptrace will disable single step unless explicitly - * asked to re-enable it. For other clients, it makes - * sense to leave it enabled (i.e. rewind the controls - * to the active-not-pending state). - */ - user_rewind_single_step(current); - } else { - pr_warn("Unexpected kernel single-step exception at EL1\n"); - /* - * Re-enable stepping since we know that we will be - * returning to regs. - */ - set_regs_spsr_ss(regs); - } +void do_el1_softstep(unsigned long esr, struct pt_regs *regs) +{ + if (kgdb_single_step_handler(regs, esr) == DBG_HOOK_HANDLED) + return; - return 0; + pr_warn("Unexpected kernel single-step exception at EL1\n"); + /* + * Re-enable stepping since we know that we will be + * returning to regs. + */ + set_regs_spsr_ss(regs); } -NOKPROBE_SYMBOL(single_step_handler); +NOKPROBE_SYMBOL(do_el1_softstep); static int call_break_hook(struct pt_regs *regs, unsigned long esr) { @@ -329,8 +312,6 @@ NOKPROBE_SYMBOL(try_handle_aarch32_break); void __init debug_traps_init(void) { - hook_debug_fault_code(DBG_ESR_EVT_HWSS, single_step_handler, SIGTRAP, - TRAP_TRACE, "single-step handler"); hook_debug_fault_code(DBG_ESR_EVT_BRK, brk_handler, SIGTRAP, TRAP_BRKPT, "BRK handler"); } diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c index be2add6b4ae3..7265bef96672 100644 --- a/arch/arm64/kernel/entry-common.c +++ b/arch/arm64/kernel/entry-common.c @@ -535,6 +535,24 @@ static void noinstr el1_breakpt(struct pt_regs *regs, unsigned long esr) arm64_exit_el1_dbg(regs); } +static void noinstr el1_softstp(struct pt_regs *regs, unsigned long esr) +{ + arm64_enter_el1_dbg(regs); + if (!cortex_a76_erratum_1463225_debug_handler(regs)) { + debug_exception_enter(regs); + /* + * After handling a breakpoint, we suspend the breakpoint + * and use single-step to move to the next instruction. + * If we are stepping a suspended breakpoint there's nothing more to do: + * the single-step is complete. + */ + if (!try_step_suspended_breakpoints(regs)) + do_el1_softstep(esr, regs); + debug_exception_exit(regs); + } + arm64_exit_el1_dbg(regs); +} + static void noinstr el1_dbg(struct pt_regs *regs, unsigned long esr) { unsigned long far = read_sysreg(far_el1); @@ -587,6 +605,8 @@ asmlinkage void noinstr el1h_64_sync_handler(struct pt_regs *regs) el1_breakpt(regs, esr); break; case ESR_ELx_EC_SOFTSTP_CUR: + el1_softstp(regs, esr); + break; case ESR_ELx_EC_WATCHPT_CUR: case ESR_ELx_EC_BRK64: el1_dbg(regs, esr); @@ -793,6 +813,25 @@ static void noinstr el0_breakpt(struct pt_regs *regs, unsigned long esr) exit_to_user_mode(regs); } +static void noinstr el0_softstp(struct pt_regs *regs, unsigned long esr) +{ + if (!is_ttbr0_addr(regs->pc)) + arm64_apply_bp_hardening(); + + enter_from_user_mode(regs); + /* + * After handling a breakpoint, we suspend the breakpoint + * and use single-step to move to the next instruction. + * If we are stepping a suspended breakpoint there's nothing more to do: + * the single-step is complete. + */ + if (!try_step_suspended_breakpoints(regs)) { + local_daif_restore(DAIF_PROCCTX); + do_el0_softstep(esr, regs); + } + exit_to_user_mode(regs); +} + static void noinstr el0_dbg(struct pt_regs *regs, unsigned long esr) { /* Only watchpoints write FAR_EL1, otherwise its UNKNOWN */ @@ -875,6 +914,8 @@ asmlinkage void noinstr el0t_64_sync_handler(struct pt_regs *regs) el0_breakpt(regs, esr); break; case ESR_ELx_EC_SOFTSTP_LOW: + el0_softstp(regs, esr); + break; case ESR_ELx_EC_WATCHPT_LOW: case ESR_ELx_EC_BRK64: el0_dbg(regs, esr); @@ -997,6 +1038,8 @@ asmlinkage void noinstr el0t_32_sync_handler(struct pt_regs *regs) el0_breakpt(regs, esr); break; case ESR_ELx_EC_SOFTSTP_LOW: + el0_softstp(regs, esr); + break; case ESR_ELx_EC_WATCHPT_LOW: case ESR_ELx_EC_BKPT32: el0_dbg(regs, esr); diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_breakpoint.c index 309ae24d4548..8a80e13347c8 100644 --- a/arch/arm64/kernel/hw_breakpoint.c +++ b/arch/arm64/kernel/hw_breakpoint.c @@ -854,7 +854,7 @@ bool try_step_suspended_breakpoints(struct pt_regs *regs) bool handled_exception = false; /* - * Called from single-step exception handler. + * Called from single-step exception entry. * Return true if we stepped a breakpoint and can resume execution, * false if we need to handle a single-step. */ |