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start: Zero the link and frame pointer registers on all architectures.

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Alex Rønne Petersen 2024-11-12 18:06:42 +01:00
parent 8af82621d7
commit 43b6bd4243
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1 changed files with 22 additions and 5 deletions
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27
lib/std/start.zig
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@ -279,8 +279,10 @@ fn _start() callconv(.naked) noreturn {
,
.arm, .armeb, .thumb, .thumbeb =>
// Note that this code must work for Thumb-1.
// r7 = FP (local), r11 = FP (unwind)
\\ movs v1, #0
\\ mov fp, v1
\\ mov r7, v1
\\ mov r11, v1
\\ mov lr, v1
\\ mov a1, sp
\\ subs v1, #16
@ -290,20 +292,23 @@ fn _start() callconv(.naked) noreturn {
,
.csky =>
// The CSKY ABI assumes that `gb` is set to the address of the GOT in order for
// position-independent code to work. We depend on this in `std.os.linux.start_pie`
// to locate `_DYNAMIC` as well.
// position-independent code to work. We depend on this in `std.os.linux.pie` to locate
// `_DYNAMIC` as well.
// r8 = FP
\\ grs t0, 1f
\\ 1:
\\ lrw gb, 1b@GOTPC
\\ addu gb, t0
\\ movi r8, 0
\\ movi lr, 0
\\ mov a0, sp
\\ andi sp, sp, -8
\\ jmpi %[posixCallMainAndExit]
,
.hexagon =>
// r29 = SP, r30 = FP
// r29 = SP, r30 = FP, r31 = LR
\\ r30 = #0
\\ r31 = #0
\\ r0 = r29
\\ r29 = and(r29, #-16)
\\ memw(r29 + #-8) = r29
@ -312,12 +317,13 @@ fn _start() callconv(.naked) noreturn {
,
.loongarch32, .loongarch64 =>
\\ move $fp, $zero
\\ move $ra, $zero
\\ move $a0, $sp
\\ bstrins.d $sp, $zero, 3, 0
\\ b %[posixCallMainAndExit]
,
.riscv32, .riscv64 =>
\\ li s0, 0
\\ li fp, 0
\\ li ra, 0
\\ mv a0, sp
\\ andi sp, sp, -16
@ -371,28 +377,35 @@ fn _start() callconv(.naked) noreturn {
,
.powerpc, .powerpcle =>
// Set up the initial stack frame, and clear the back chain pointer.
// r1 = SP, r31 = FP
\\ mr 3, 1
\\ clrrwi 1, 1, 4
\\ li 0, 0
\\ stwu 1, -16(1)
\\ stw 0, 0(1)
\\ li 31, 0
\\ mtlr 0
\\ b %[posixCallMainAndExit]
,
.powerpc64, .powerpc64le =>
// Set up the ToC and initial stack frame, and clear the back chain pointer.
// r1 = SP, r2 = ToC, r31 = FP
\\ addis 2, 12, .TOC. - %[_start]@ha
\\ addi 2, 2, .TOC. - %[_start]@l
\\ mr 3, 1
\\ clrrdi 1, 1, 4
\\ li 0, 0
\\ stdu 0, -32(1)
\\ li 31, 0
\\ mtlr 0
\\ b %[posixCallMainAndExit]
\\ nop
,
.s390x =>
// Set up the stack frame (register save area and cleared back-chain slot).
// r11 = FP, r14 = LR, r15 = SP
\\ lghi %%r11, 0
\\ lghi %%r14, 0
\\ lgr %%r2, %%r15
\\ lghi %%r0, -16
\\ ngr %%r15, %%r0
@ -403,7 +416,9 @@ fn _start() callconv(.naked) noreturn {
,
.sparc =>
// argc is stored after a register window (16 registers * 4 bytes).
// i7 = LR
\\ mov %%g0, %%fp
\\ mov %%g0, %%i7
\\ add %%sp, 64, %%o0
\\ and %%sp, -8, %%sp
\\ ba,a %[posixCallMainAndExit]
@ -411,7 +426,9 @@ fn _start() callconv(.naked) noreturn {
.sparc64 =>
// argc is stored after a register window (16 registers * 8 bytes) plus the stack bias
// (2047 bytes).
// i7 = LR
\\ mov %%g0, %%fp
\\ mov %%g0, %%i7
\\ add %%sp, 2175, %%o0
\\ add %%sp, 2047, %%sp
\\ and %%sp, -16, %%sp