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| author | Vineet Gupta <vgupta@kernel.org> | 2020-05-14 10:16:34 +0300 |
|---|---|---|
| committer | Vineet Gupta <vgupta@kernel.org> | 2023-08-18 06:31:59 +0300 |
| commit | b060b7d0c105d495eb9338a3f6c7bc0c09830a2c (patch) | |
| tree | 76eaa8ad16e4dc7728a35912de754b27e2ed218c /arch/arc/include/asm | |
| parent | d1d1569e89e9cc5c07a389ac859bd045b906923c (diff) | |
| download | linux-b060b7d0c105d495eb9338a3f6c7bc0c09830a2c.tar.xz | |
ARC: __switch_to: asm with dwarf ops (vs. inline asm)
__switch_to() is final step of context switch, swapping kernel modes
stack (and callee regs) of outgoing task with next task.
It is also the starting point of stack unwinging of a sleeping task and
captures SP, FP, BLINK and the corresponding dwarf info. Back when
dinosaurs still roamed around, ARC gas didn't support CFI pseudo ops and
gcc was responsible for generating dwarf info. Thus it had to be written
in "C" with inline asm to do the hand crafting of stack. The function
prologue (and crucial saving of blink etc) was still gcc generated but
not visible in code. Likewise dwarf info was missing.
Now with modern tools, we can make things more obvious by writing the
code in asm and adding approproate dwarf cfi pseudo ops.
This is mostly non functional change, except for slight chnages to asm
- ARCompact doesn't support MOV_S fp, sp, so we use MOV
Signed-off-by: Vineet Gupta <vgupta@kernel.org>
Diffstat (limited to 'arch/arc/include/asm')
| -rw-r--r-- | arch/arc/include/asm/dwarf.h | 32 |
1 files changed, 20 insertions, 12 deletions
diff --git a/arch/arc/include/asm/dwarf.h b/arch/arc/include/asm/dwarf.h index 5f4de05bd4ee..a0d5ebe1bc3f 100644 --- a/arch/arc/include/asm/dwarf.h +++ b/arch/arc/include/asm/dwarf.h @@ -10,23 +10,31 @@ #ifdef ARC_DW2_UNWIND_AS_CFI -#define CFI_STARTPROC .cfi_startproc -#define CFI_ENDPROC .cfi_endproc -#define CFI_DEF_CFA .cfi_def_cfa -#define CFI_REGISTER .cfi_register -#define CFI_REL_OFFSET .cfi_rel_offset -#define CFI_UNDEFINED .cfi_undefined +#define CFI_STARTPROC .cfi_startproc +#define CFI_ENDPROC .cfi_endproc +#define CFI_DEF_CFA .cfi_def_cfa +#define CFI_DEF_CFA_OFFSET .cfi_def_cfa_offset +#define CFI_DEF_CFA_REGISTER .cfi_def_cfa_register +#define CFI_OFFSET .cfi_offset +#define CFI_REL_OFFSET .cfi_rel_offset +#define CFI_REGISTER .cfi_register +#define CFI_RESTORE .cfi_restore +#define CFI_UNDEFINED .cfi_undefined #else #define CFI_IGNORE # -#define CFI_STARTPROC CFI_IGNORE -#define CFI_ENDPROC CFI_IGNORE -#define CFI_DEF_CFA CFI_IGNORE -#define CFI_REGISTER CFI_IGNORE -#define CFI_REL_OFFSET CFI_IGNORE -#define CFI_UNDEFINED CFI_IGNORE +#define CFI_STARTPROC CFI_IGNORE +#define CFI_ENDPROC CFI_IGNORE +#define CFI_DEF_CFA CFI_IGNORE +#define CFI_DEF_CFA_OFFSET CFI_IGNORE +#define CFI_DEF_CFA_REGISTER CFI_IGNORE +#define CFI_OFFSET CFI_IGNORE +#define CFI_REL_OFFSET CFI_IGNORE +#define CFI_REGISTER CFI_IGNORE +#define CFI_RESTORE CFI_IGNORE +#define CFI_UNDEFINED CFI_IGNORE #endif /* !ARC_DW2_UNWIND_AS_CFI */ |