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kern: add hardware single step extension

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Michael Scire 2021-07-27 05:34:40 -07:00 • committed by SciresM
parent 904ab19823
commit 4075d24e0c
10 changed files with 226 additions and 4 deletions
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36
libraries/libmesosphere/source/arch/arm64/svc/kern_svc_exception_asm.s
View file

@ -15,6 +15,39 @@
*/
#include <mesosphere/kern_select_assembly_offsets.h>
#if defined(MESOSPHERE_ENABLE_HARDWARE_SINGLE_STEP)
.macro disable_single_step, scratch
/* Clear MDSCR_EL1.SS. */
mrs \scratch, mdscr_el1
bic \scratch, \scratch, #1
msr mdscr_el1, \scratch
.endm
.macro check_enable_single_step, scratch1, scratch2, spsr_value
/* Check if single-step is requested. */
ldrb \scratch1, [sp, #(EXCEPTION_CONTEXT_SIZE + THREAD_STACK_PARAMETERS_IS_SINGLE_STEP)]
tbz \scratch1, #0, .skip_single_step\@
/* If single-step is requested, enable the single-step machine by setting MDSCR_EL1.SS. */
mrs \scratch2, mdscr_el1
orr \scratch2, \scratch2, #1
msr mdscr_el1, \scratch2
/* Since we're returning from an exception, set SPSR.SS so we actually advance an instruction. */
orr \spsr_value, \spsr_value, #(1 << 21)
isb
.skip_single_step\@:
.endm
#else
.macro disable_single_step, scratch
.endm
.macro check_enable_single_step, scratch1, scratch2, spsr_value
.endm
#endif
/* ams::kern::svc::CallReturnFromException64(Result result) */
.section .text._ZN3ams4kern3svc25CallReturnFromException64Ev, "ax", %progbits
.global _ZN3ams4kern3svc25CallReturnFromException64Ev
@ -89,6 +122,9 @@ _ZN3ams4kern3svc14RestoreContextEm:
ldp x30, x8, [sp, #(EXCEPTION_CONTEXT_X30_SP)]
ldp x9, x10, [sp, #(EXCEPTION_CONTEXT_PC_PSR)]
ldr x11, [sp, #(EXCEPTION_CONTEXT_TPIDR)]
check_enable_single_step w0, x0, x10
msr sp_el0, x8
msr elr_el1, x9
msr spsr_el1, x10

51
libraries/libmesosphere/source/arch/arm64/svc/kern_svc_handlers_asm.s
View file

@ -16,6 +16,39 @@
#include <mesosphere/kern_build_config.hpp>
#include <mesosphere/kern_select_assembly_offsets.h>
#if defined(MESOSPHERE_ENABLE_HARDWARE_SINGLE_STEP)
.macro disable_single_step, scratch
/* Clear MDSCR_EL1.SS. */
mrs \scratch, mdscr_el1
bic \scratch, \scratch, #1
msr mdscr_el1, \scratch
.endm
.macro check_enable_single_step, scratch1, scratch2, spsr_value
/* Check if single-step is requested. */
ldrb \scratch1, [sp, #(EXCEPTION_CONTEXT_SIZE + THREAD_STACK_PARAMETERS_IS_SINGLE_STEP)]
tbz \scratch1, #0, .skip_single_step\@
/* If single-step is requested, enable the single-step machine by setting MDSCR_EL1.SS. */
mrs \scratch2, mdscr_el1
orr \scratch2, \scratch2, #1
msr mdscr_el1, \scratch2
/* Since we're returning from an SVC, make sure SPSR.SS is cleared so we break instantly on the instruction after the SVC. */
bic \spsr_value, \spsr_value, #(1 << 21)
isb
.skip_single_step\@:
.endm
#else
.macro disable_single_step, scratch
.endm
.macro check_enable_single_step, scratch1, scratch2, spsr_value
.endm
#endif
/* ams::kern::arch::arm64::SvcHandler64() */
.section .text._ZN3ams4kern4arch5arm6412SvcHandler64Ev, "ax", %progbits
.global _ZN3ams4kern4arch5arm6412SvcHandler64Ev
@ -51,6 +84,9 @@ _ZN3ams4kern4arch5arm6412SvcHandler64Ev:
stp x8, x9, [sp, #(EXCEPTION_CONTEXT_SP_PC)]
stp x10, x11, [sp, #(EXCEPTION_CONTEXT_PSR_TPIDR)]
/* Disable single-step. */
disable_single_step x8
/* Check if the SVC index is out of range. */
mrs x8, esr_el1
and x8, x8, #0xFF
@ -154,6 +190,9 @@ _ZN3ams4kern4arch5arm6412SvcHandler64Ev:
ldp x30, x8, [sp, #(EXCEPTION_CONTEXT_X30_SP)]
ldp x9, x10, [sp, #(EXCEPTION_CONTEXT_PC_PSR)]
ldr x11, [sp, #(EXCEPTION_CONTEXT_TPIDR)]
check_enable_single_step w0, x0, x10
msr sp_el0, x8
msr elr_el1, x9
msr spsr_el1, x10
@ -203,6 +242,9 @@ _ZN3ams4kern4arch5arm6412SvcHandler64Ev:
ldp x9, x10, [sp, #(EXCEPTION_CONTEXT_PC_PSR)]
ldr x11, [sp, #(EXCEPTION_CONTEXT_TPIDR)]
ldr x18, [sp, #(EXCEPTION_CONTEXT_X18)]
check_enable_single_step w12, x12, x10
msr sp_el0, x8
msr elr_el1, x9
msr spsr_el1, x10
@ -260,6 +302,9 @@ _ZN3ams4kern4arch5arm6412SvcHandler32Ev:
stp x12, x13, [sp, #(EXCEPTION_CONTEXT_X12_X13)]
stp x14, xzr, [sp, #(EXCEPTION_CONTEXT_X14_X15)]
/* Disable single-step. */
disable_single_step x8
/* Check if the SVC index is out of range. */
mrs x16, esr_el1
and x16, x16, #0xFF
@ -359,6 +404,9 @@ _ZN3ams4kern4arch5arm6412SvcHandler32Ev:
/* Restore registers. */
ldp x17, x20, [sp, #(EXCEPTION_CONTEXT_PC_PSR)]
ldr x19, [sp, #(EXCEPTION_CONTEXT_TPIDR)]
check_enable_single_step w0, x0, x20
msr elr_el1, x17
msr spsr_el1, x20
msr tpidr_el0, x19
@ -402,6 +450,9 @@ _ZN3ams4kern4arch5arm6412SvcHandler32Ev:
ldp x14, xzr, [sp, #(EXCEPTION_CONTEXT_X14_X15)]
ldp x17, x20, [sp, #(EXCEPTION_CONTEXT_PC_PSR)]
ldr x19, [sp, #(EXCEPTION_CONTEXT_TPIDR)]
check_enable_single_step w21, x21, x20
msr elr_el1, x17
msr spsr_el1, x20
msr tpidr_el0, x19

33
libraries/libmesosphere/source/kern_k_debug_base.cpp
View file

@ -372,6 +372,14 @@ namespace ams::kern {
new_state = state;
}
/* Clear single step on all threads. */
{
auto end = target->GetThreadList().end();
for (auto it = target->GetThreadList().begin(); it != end; ++it) {
it->ClearSingleStep();
}
}
/* Detach from the process. */
target->ClearDebugObject(new_state);
m_process = nullptr;
@ -479,6 +487,25 @@ namespace ams::kern {
}
}
/* Update thread single-step state. */
#if defined(MESOSPHERE_ENABLE_HARDWARE_SINGLE_STEP)
{
if ((context_flags & ams::svc::ThreadContextFlag_SetSingleStep) != 0) {
/* Set single step. */
thread->SetSingleStep();
/* If no other thread flags are present, we're done. */
R_SUCCEED_IF((context_flags & ~ams::svc::ThreadContextFlag_SetSingleStep) == 0);
} else if ((context_flags & ams::svc::ThreadContextFlag_ClearSingleStep) != 0) {
/* Clear single step. */
thread->ClearSingleStep();
/* If no other thread flags are present, we're done. */
R_SUCCEED_IF((context_flags & ~ams::svc::ThreadContextFlag_ClearSingleStep) == 0);
}
}
#endif
/* Verify that the thread's svc state is valid. */
if (thread->IsCallingSvc()) {
const u8 svc_id = thread->GetSvcId();
@ -873,6 +900,9 @@ namespace ams::kern {
{
auto end = process->GetThreadList().end();
for (auto it = process->GetThreadList().begin(); it != end; ++it) {
/* Clear the thread's single-step state. */
it->ClearSingleStep();
if (resume) {
/* If the process isn't crashed, resume threads. */
it->Resume(KThread::SuspendType_Debug);
@ -960,9 +990,10 @@ namespace ams::kern {
/* Set the process as breaked. */
process->SetDebugBreak();
/* If the event is an exception, set the result. */
/* If the event is an exception, set the result and clear single step. */
if (event == ams::svc::DebugEvent_Exception) {
GetCurrentThread().SetDebugExceptionResult(ResultSuccess());
GetCurrentThread().ClearSingleStep();
}
/* Exit our retry loop. */

19
libraries/libmesosphere/source/svc/kern_svc_debug.cpp
View file

@ -186,7 +186,24 @@ namespace ams::kern::svc {
R_UNLESS(KTargetSystem::IsDebugMode(), svc::ResultNotImplemented());
/* Validate the context flags. */
R_UNLESS((context_flags | ams::svc::ThreadContextFlag_All) == ams::svc::ThreadContextFlag_All, svc::ResultInvalidEnumValue());
#if defined(MESOSPHERE_ENABLE_HARDWARE_SINGLE_STEP)
{
/* Check that the flags are a subset of the allowable. */
constexpr u32 AllFlagsMask = ams::svc::ThreadContextFlag_All | ams::svc::ThreadContextFlag_SetSingleStep | ams::svc::ThreadContextFlag_ClearSingleStep;
R_UNLESS((context_flags | AllFlagsMask) == AllFlagsMask, svc::ResultInvalidEnumValue());
/* Check that thread isn't both setting and clearing single step. */
const bool set_ss = (context_flags & ams::svc::ThreadContextFlag_SetSingleStep) != 0;
const bool clear_ss = (context_flags & ams::svc::ThreadContextFlag_ClearSingleStep) != 0;
R_UNLESS(!(set_ss && clear_ss), svc::ResultInvalidEnumValue());
}
#else
{
/* Check that the flags are a subset of the allowable. */
R_UNLESS((context_flags | ams::svc::ThreadContextFlag_All) == ams::svc::ThreadContextFlag_All, svc::ResultInvalidEnumValue());
}
#endif
/* Copy the thread context from userspace. */
ams::svc::ThreadContext context;

10
libraries/libmesosphere/source/svc/kern_svc_info.cpp
View file

@ -271,6 +271,16 @@ namespace ams::kern::svc {
*out = KTraceValue;
}
break;
case ams::svc::MesosphereMetaInfo_IsSingleStepEnabled:
{
/* Return whether the kernel supports hardware single step. */
#if defined(MESOSPHERE_ENABLE_HARDWARE_SINGLE_STEP)
*out = 1;
#else
*out = 0;
#endif
}
break;
default:
return svc::ResultInvalidCombination();
}