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folkertdevfolkertdev
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indent the probestack inline assembly
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‎library/compiler-builtins/compiler-builtins/src/probestack.rs‎

Lines changed: 110 additions & 186 deletions
Original file line numberDiff line numberDiff line change
@@ -49,82 +49,6 @@
4949
// We only define stack probing for these architectures today.
5050
#![cfg(any(target_arch = "x86_64", target_arch = "x86"))]
5151

52-
<<<<<<< HEAD
53-
// SAFETY: defined in this module.
54-
// FIXME(extern_custom): the ABI is not correct.
55-
unsafe extern "C" {
56-
pub fn __rust_probestack();
57-
}
58-
59-
// A wrapper for our implementation of __rust_probestack, which allows us to
60-
// keep the assembly inline while controlling all CFI directives in the assembly
61-
// emitted for the function.
62-
//
63-
// This is the ELF version.
64-
#[cfg(not(any(target_vendor = "apple", target_os = "uefi")))]
65-
macro_rules! define_rust_probestack {
66-
($body: expr) => {
67-
concat!(
68-
"
69-
.pushsection .text.__rust_probestack
70-
.globl __rust_probestack
71-
.type __rust_probestack, @function
72-
.hidden __rust_probestack
73-
__rust_probestack:
74-
",
75-
$body,
76-
"
77-
.size __rust_probestack, . - __rust_probestack
78-
.popsection
79-
"
80-
)
81-
};
82-
}
83-
84-
#[cfg(all(target_os = "uefi", target_arch = "x86_64"))]
85-
macro_rules! define_rust_probestack {
86-
($body: expr) => {
87-
concat!(
88-
"
89-
.globl __rust_probestack
90-
__rust_probestack:
91-
",
92-
$body
93-
)
94-
};
95-
}
96-
97-
// Same as above, but for Mach-O. Note that the triple underscore
98-
// is deliberate
99-
#[cfg(target_vendor = "apple")]
100-
macro_rules! define_rust_probestack {
101-
($body: expr) => {
102-
concat!(
103-
"
104-
.globl ___rust_probestack
105-
___rust_probestack:
106-
",
107-
$body
108-
)
109-
};
110-
}
111-
112-
// In UEFI x86 arch, triple underscore is deliberate.
113-
#[cfg(all(target_os = "uefi", target_arch = "x86"))]
114-
macro_rules! define_rust_probestack {
115-
($body: expr) => {
116-
concat!(
117-
"
118-
.globl ___rust_probestack
119-
___rust_probestack:
120-
",
121-
$body
122-
)
123-
};
124-
}
125-
126-
=======
127-
>>>>>>> d6dd2696443 (use `#[naked]` for `__rust_probestack`)
12852
// Our goal here is to touch each page between %rsp+8 and %rsp+8-%rax,
12953
// ensuring that if any pages are unmapped we'll make a page fault.
13054
//
@@ -159,56 +83,56 @@ pub unsafe extern "C" fn __rust_probestack() {
15983

16084
core::arch::naked_asm!(
16185
"
162-
.cfi_startproc
163-
pushq %rbp
164-
.cfi_adjust_cfa_offset 8
165-
.cfi_offset %rbp, -16
166-
movq %rsp, %rbp
167-
.cfi_def_cfa_register %rbp
168-
169-
mov %rax,%r11 // duplicate %rax as we're clobbering %r11
170-
171-
// Main loop, taken in one page increments. We're decrementing rsp by
172-
// a page each time until there's less than a page remaining. We're
173-
// guaranteed that this function isn't called unless there's more than a
174-
// page needed.
175-
//
176-
// Note that we're also testing against `8(%rsp)` to account for the 8
177-
// bytes pushed on the stack orginally with our return address. Using
178-
// `8(%rsp)` simulates us testing the stack pointer in the caller's
179-
// context.
180-
181-
// It's usually called when %rax >= 0x1000, but that's not always true.
182-
// Dynamic stack allocation, which is needed to implement unsized
183-
// rvalues, triggers stackprobe even if %rax < 0x1000.
184-
// Thus we have to check %r11 first to avoid segfault.
185-
cmp $0x1000,%r11
186-
jna 3f
187-
2:
188-
sub $0x1000,%rsp
189-
test %rsp,8(%rsp)
190-
sub $0x1000,%r11
191-
cmp $0x1000,%r11
192-
ja 2b
193-
194-
3:
195-
// Finish up the last remaining stack space requested, getting the last
196-
// bits out of r11
197-
sub %r11,%rsp
198-
test %rsp,8(%rsp)
199-
200-
// Restore the stack pointer to what it previously was when entering
201-
// this function. The caller will readjust the stack pointer after we
202-
// return.
203-
add %rax,%rsp
204-
205-
leave
206-
.cfi_def_cfa_register %rsp
207-
.cfi_adjust_cfa_offset -8
86+
.cfi_startproc
87+
pushq %rbp
88+
.cfi_adjust_cfa_offset 8
89+
.cfi_offset %rbp, -16
90+
movq %rsp, %rbp
91+
.cfi_def_cfa_register %rbp
92+
93+
mov %rax,%r11 // duplicate %rax as we're clobbering %r11
94+
95+
// Main loop, taken in one page increments. We're decrementing rsp by
96+
// a page each time until there's less than a page remaining. We're
97+
// guaranteed that this function isn't called unless there's more than a
98+
// page needed.
99+
//
100+
// Note that we're also testing against `8(%rsp)` to account for the 8
101+
// bytes pushed on the stack orginally with our return address. Using
102+
// `8(%rsp)` simulates us testing the stack pointer in the caller's
103+
// context.
104+
105+
// It's usually called when %rax >= 0x1000, but that's not always true.
106+
// Dynamic stack allocation, which is needed to implement unsized
107+
// rvalues, triggers stackprobe even if %rax < 0x1000.
108+
// Thus we have to check %r11 first to avoid segfault.
109+
cmp $0x1000,%r11
110+
jna 3f
111+
2:
112+
sub $0x1000,%rsp
113+
test %rsp,8(%rsp)
114+
sub $0x1000,%r11
115+
cmp $0x1000,%r11
116+
ja 2b
117+
118+
3:
119+
// Finish up the last remaining stack space requested, getting the last
120+
// bits out of r11
121+
sub %r11,%rsp
122+
test %rsp,8(%rsp)
123+
124+
// Restore the stack pointer to what it previously was when entering
125+
// this function. The caller will readjust the stack pointer after we
126+
// return.
127+
add %rax,%rsp
128+
129+
leave
130+
.cfi_def_cfa_register %rsp
131+
.cfi_adjust_cfa_offset -8
208132
",
209133
ret!(),
210134
"
211-
.cfi_endproc
135+
.cfi_endproc
212136
",
213137
options(att_syntax)
214138
)
@@ -227,35 +151,35 @@ pub unsafe extern "C" fn __rust_probestack() {
227151
pub unsafe extern "C" fn __rust_probestack() {
228152
core::arch::naked_asm!(
229153
"
230-
.cfi_startproc
231-
push %ebp
232-
.cfi_adjust_cfa_offset 4
233-
.cfi_offset %ebp, -8
234-
mov %esp, %ebp
235-
.cfi_def_cfa_register %ebp
236-
push %ecx
237-
mov %eax,%ecx
238-
239-
cmp $0x1000,%ecx
240-
jna 3f
241-
2:
242-
sub $0x1000,%esp
243-
test %esp,8(%esp)
244-
sub $0x1000,%ecx
245-
cmp $0x1000,%ecx
246-
ja 2b
247-
248-
3:
249-
sub %ecx,%esp
250-
test %esp,8(%esp)
251-
252-
add %eax,%esp
253-
pop %ecx
254-
leave
255-
.cfi_def_cfa_register %esp
256-
.cfi_adjust_cfa_offset -4
257-
ret
258-
.cfi_endproc
154+
.cfi_startproc
155+
push %ebp
156+
.cfi_adjust_cfa_offset 4
157+
.cfi_offset %ebp, -8
158+
mov %esp, %ebp
159+
.cfi_def_cfa_register %ebp
160+
push %ecx
161+
mov %eax,%ecx
162+
163+
cmp $0x1000,%ecx
164+
jna 3f
165+
2:
166+
sub $0x1000,%esp
167+
test %esp,8(%esp)
168+
sub $0x1000,%ecx
169+
cmp $0x1000,%ecx
170+
ja 2b
171+
172+
3:
173+
sub %ecx,%esp
174+
test %esp,8(%esp)
175+
176+
add %eax,%esp
177+
pop %ecx
178+
leave
179+
.cfi_def_cfa_register %esp
180+
.cfi_adjust_cfa_offset -4
181+
ret
182+
.cfi_endproc
259183
",
260184
options(att_syntax)
261185
)
@@ -279,40 +203,40 @@ pub unsafe extern "C" fn __rust_probestack() {
279203
pub unsafe extern "C" fn __rust_probestack() {
280204
core::arch::naked_asm!(
281205
"
282-
.cfi_startproc
283-
push %ebp
284-
.cfi_adjust_cfa_offset 4
285-
.cfi_offset %ebp, -8
286-
mov %esp, %ebp
287-
.cfi_def_cfa_register %ebp
288-
push %ecx
289-
push %edx
290-
mov %eax,%ecx
291-
292-
cmp $0x1000,%ecx
293-
jna 3f
294-
2:
295-
sub $0x1000,%esp
296-
test %esp,8(%esp)
297-
sub $0x1000,%ecx
298-
cmp $0x1000,%ecx
299-
ja 2b
300-
301-
3:
302-
sub %ecx,%esp
303-
test %esp,8(%esp)
304-
mov 4(%ebp),%edx
305-
mov %edx, 12(%esp)
306-
add %eax,%esp
307-
pop %edx
308-
pop %ecx
309-
leave
310-
311-
sub %eax, %esp
312-
.cfi_def_cfa_register %esp
313-
.cfi_adjust_cfa_offset -4
314-
ret
315-
.cfi_endproc
206+
.cfi_startproc
207+
push %ebp
208+
.cfi_adjust_cfa_offset 4
209+
.cfi_offset %ebp, -8
210+
mov %esp, %ebp
211+
.cfi_def_cfa_register %ebp
212+
push %ecx
213+
push %edx
214+
mov %eax,%ecx
215+
216+
cmp $0x1000,%ecx
217+
jna 3f
218+
2:
219+
sub $0x1000,%esp
220+
test %esp,8(%esp)
221+
sub $0x1000,%ecx
222+
cmp $0x1000,%ecx
223+
ja 2b
224+
225+
3:
226+
sub %ecx,%esp
227+
test %esp,8(%esp)
228+
mov 4(%ebp),%edx
229+
mov %edx, 12(%esp)
230+
add %eax,%esp
231+
pop %edx
232+
pop %ecx
233+
leave
234+
235+
sub %eax, %esp
236+
.cfi_def_cfa_register %esp
237+
.cfi_adjust_cfa_offset -4
238+
ret
239+
.cfi_endproc
316240
",
317241
options(att_syntax)
318242
)

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