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demon/linux: x64 register reading

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This commit is contained in:
Ryan Fleury
2025-07-29 14:19:35 -07:00
parent 92e6069104
commit 7403a8ea3b
6 changed files with 419 additions and 13 deletions
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src/demon/linux/demon_core_linux.c
+229 -5
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@@ -532,6 +532,174 @@ dmn_lnx_thread_from_pid(pid_t pid)
return result;
}
internal B32
dmn_lnx_thread_read_reg_block(DMN_LNX_Entity *thread, void *reg_block)
{
B32 result = 0;
{
REGS_RegBlockX64 *dst = (REGS_RegBlockX64 *)reg_block;
pid_t tid = (pid_t)thread->id;
//- rjf: read GPR
B32 got_gpr = 0;
{
DMN_LNX_UserX64 ctx = {0};
struct iovec iov_gpr = {0};
iov_gpr.iov_len = sizeof(ctx);
iov_gpr.iov_base = &ctx;
if(ptrace(PTRACE_GETREGSET, tid, (void*)NT_PRSTATUS, &iov_gpr) != -1)
{
got_gpr = 1;
DMN_LNX_UserRegsX64 *src = &ctx.regs;
dst->rax.u64 = src->rax;
dst->rcx.u64 = src->rcx;
dst->rdx.u64 = src->rdx;
dst->rbx.u64 = src->rbx;
dst->rsp.u64 = src->rsp;
dst->rbp.u64 = src->rbp;
dst->rsi.u64 = src->rsi;
dst->rdi.u64 = src->rdi;
dst->r8.u64 = src->r8;
dst->r9.u64 = src->r9;
dst->r10.u64 = src->r10;
dst->r11.u64 = src->r11;
dst->r12.u64 = src->r12;
dst->r13.u64 = src->r13;
dst->r14.u64 = src->r14;
dst->r15.u64 = src->r15;
dst->cs.u16 = src->cs;
dst->ds.u16 = src->ds;
dst->es.u16 = src->es;
dst->fs.u16 = src->fs;
dst->gs.u16 = src->gs;
dst->ss.u16 = src->ss;
dst->fsbase.u64 = src->fsbase;
dst->gsbase.u64 = src->gsbase;
dst->rip.u64 = src->rip;
dst->rflags.u64 = src->rflags;
}
}
//- rjf: read FPR
B32 got_fpr = 0;
if(got_gpr)
{
Temp scratch = scratch_begin(0, 0);
DMN_LNX_XSave *xsave = 0;
DMN_LNX_XSaveLegacy *xsave_legacy = 0;
// rjf: try xsave
if(!xsave_legacy)
{
U8 xsave_buffer[KB(4)];
struct iovec iov_xsave = {0};
iov_xsave.iov_len = sizeof(xsave_buffer);
iov_xsave.iov_base = xsave_buffer;
if(ptrace(PTRACE_GETREGSET, tid, (void*)NT_X86_XSTATE, &iov_xsave) != -1)
{
xsave = push_array_no_zero(scratch.arena, DMN_LNX_XSave, 1);
MemoryCopy(xsave, xsave_buffer, sizeof(*xsave));
xsave_legacy = &xsave->legacy;
}
}
// rjf: try fxsave
if(!xsave_legacy)
{
DMN_LNX_XSaveLegacy fxsave = {0};
struct iovec iov_fxsave = {0};
iov_fxsave.iov_len = sizeof(fxsave);
iov_fxsave.iov_base = &fxsave;
if(ptrace(PTRACE_GETREGSET, tid, (void *)NT_FPREGSET, &iov_fxsave) != -1)
{
xsave_legacy = push_array_no_zero(scratch.arena, DMN_LNX_XSaveLegacy, 1);
MemoryCopy(xsave_legacy, &fxsave, sizeof(*xsave_legacy));
}
}
// rjf: fill from xsave legacy
if(xsave_legacy)
{
DMN_LNX_XSaveLegacy *src = xsave_legacy;
dst->fcw.u16 = src->fcw;
dst->fsw.u16 = src->fsw;
dst->ftw.u16 = src->ftw; // TODO(rjf): old: fix tag word (?)
dst->fop.u16 = src->fop;
dst->fip.u64 = src->b64.fip;
// TODO(rjf): these 16-bit registers do not belong in x64
dst->fcs.u16 = 0;
dst->fdp.u64 = src->b64.fdp;
dst->fds.u16 = 0;
dst->mxcsr.u32 = src->mxcsr;
dst->mxcsr_mask.u32 = src->mxcsr_mask;
{
U8 *float_s = src->st_space.u8;
REGS_Reg80 *float_d = &dst->st0;
for(U32 n = 0; n < 8; n += 1, float_s += 16, float_d += 1)
{
MemoryCopy(float_d, float_s, sizeof(*float_d));
}
}
{
U8 *xmm_s = src->xmm_space.u8;
REGS_Reg512 *xmm_d = &dst->zmm0;
for(U32 n = 0; n < 16; n += 1, xmm_s += 16, xmm_d += 1)
{
MemoryCopy(xmm_d, xmm_s, 16);
}
}
}
// rjf: fill from ymm registers
// TODO(rjf): this is a lie; ymm can technically move around. study & fix.
if(xsave)
{
B32 has_ymm_registers = ((xsave->header.xstate_bv & 4) != 0);
if(has_ymm_registers)
{
U8 *ymm_s = (U8 *)xsave->ymmh;
REGS_Reg512 *ymm_d = &dst->zmm0;
for(U32 n = 0; n < 16; n += 1, ymm_s += 16, ymm_d += 1)
{
MemoryCopy(((U8*)ymm_d) + 16, ymm_s, 16);
}
}
}
got_fpr = (xsave || xsave_legacy);
scratch_end(scratch);
}
//- rjf: read debug registers
B32 got_debug = 0;
if(got_fpr)
{
got_debug = 1;
REGS_Reg64 *dr_d = &dst->dr0;
for(U32 i = 0; i < 8; i += 1, dr_d += 1)
{
if(i != 4 && i != 5)
{
U64 offset = OffsetOf(DMN_LNX_UserX64, u_debugreg[i]);
errno = 0;
int peek_result = ptrace(PTRACE_PEEKUSER, tid, PtrFromInt(offset), 0);
if(errno == 0)
{
dr_d->u64 = (U64)peek_result;
}
else
{
got_debug = 0;
}
}
}
}
result = got_debug;
}
return result;
}
////////////////////////////////
//~ rjf: @dmn_os_hooks Main Layer Initialization (Implemented Per-OS)
@@ -828,6 +996,11 @@ dmn_ctrl_run(Arena *arena, DMN_CtrlCtx *ctx, DMN_RunCtrls *ctrls)
{
Temp scratch = scratch_begin(&arena, 1);
////////////////////////////
//- rjf: unpack controls
//
DMN_LNX_Entity *single_step_thread = dmn_lnx_entity_from_handle(ctrls->single_step_thread);
////////////////////////////
//- rjf: push any deferred events
//
@@ -853,12 +1026,17 @@ dmn_ctrl_run(Arena *arena, DMN_CtrlCtx *ctx, DMN_RunCtrls *ctrls)
e->error_kind = DMN_ErrorKind_NotAttached;
}
////////////////////////////
//- rjf: determine if we need to wait for new events
//
B32 need_wait_on_events = (evts.count == 0);
////////////////////////////
//- rjf: gather all threads which we should run
//
DMN_LNX_EntityNode *first_run_thread = 0;
DMN_LNX_EntityNode *last_run_thread = 0;
ProfScope("gather all threads which we should run")
if(need_wait_on_events) ProfScope("gather all threads which we should run")
{
//- rjf: scan all processes
for(DMN_LNX_Entity *process = dmn_lnx_state->entities_base->first;
@@ -956,7 +1134,7 @@ dmn_ctrl_run(Arena *arena, DMN_CtrlCtx *ctx, DMN_RunCtrls *ctrls)
//- rjf: loop: wait for next stop, produce debug events
//
pid_t final_wait_pid = 0;
for(B32 done = 0; !done;)
if(need_wait_on_events) for(B32 done = 0; !done;)
{
//- rjf: wait for next event
int status = 0;
@@ -974,6 +1152,17 @@ dmn_ctrl_run(Arena *arena, DMN_CtrlCtx *ctx, DMN_RunCtrls *ctrls)
DMN_LNX_Entity *process = thread->parent;
B32 thread_is_process_root = (thread->id == process->id);
//- rjf: unpack thread's registers
U64 rip = 0;
void *regs_block = 0;
if(thread != &dmn_lnx_nil_entity)
{
U64 regs_block_size = regs_block_size_from_arch(thread->arch);
regs_block = push_array(scratch.arena, U8, regs_block_size);
dmn_lnx_thread_read_reg_block(thread, regs_block);
rip = regs_rip_from_arch_block(thread->arch, regs_block);
}
//- rjf: WIFEXITED(status) -> thread exit
B32 thread_exit = 0;
U64 exit_code = 0;
@@ -1003,11 +1192,40 @@ dmn_ctrl_run(Arena *arena, DMN_CtrlCtx *ctx, DMN_RunCtrls *ctrls)
}
//- rjf: SIGTRAP:PTRACE_EVENT_FORK, or SIGTRAP:PTRACE_EVENT_VFORK
if(wifstopped && wstopsig == SIGTRAP &&
B32 sigtrap_handled = 0;
if(!sigtrap_handled && wifstopped && wstopsig == SIGTRAP &&
(ptrace_event_code == PTRACE_EVENT_FORK ||
ptrace_event_code == PTRACE_EVENT_VFORK))
{
// TODO(rjf)
sigtrap_handled = 1;
}
//- rjf: SIGTRAP
if(!sigtrap_handled && wifstopped && wstopsig == SIGTRAP)
{
// rjf: this is the single step thread => this is a single step completion
DMN_EventKind e_kind = DMN_EventKind_Trap;
if(thread == single_step_thread)
{
e_kind = DMN_EventKind_SingleStep;
}
// rjf: this matches a specified trap => breakpoint
{
// TODO(rjf)
}
// rjf: after breakpoint -> rollback
if(e_kind == DMN_EventKind_Breakpoint)
{
// TODO(rjf)
}
// rjf: push event
DMN_Event *e = dmn_event_list_push(arena, &evts);
e->kind = e_kind;
e->process = dmn_lnx_handle_from_entity(process);
e->thread = dmn_lnx_handle_from_entity(thread);
}
//- rjf: WSTOPSIG(status) is SIGSTOP
@@ -1243,7 +1461,13 @@ dmn_tls_root_vaddr_from_thread(DMN_Handle handle)
internal B32
dmn_thread_read_reg_block(DMN_Handle handle, void *reg_block)
{
return 0;
B32 result = 0;
DMN_AccessScope
{
DMN_LNX_Entity *thread = dmn_lnx_entity_from_handle(handle);
result = dmn_lnx_thread_read_reg_block(thread, reg_block);
}
return result;
}
internal B32