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don't save/retore gp&tp

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Signed-off-by: Wang Chen <wangchen20@iscas.ac.cn>
Co-authored-by: LiuJiLan <ldc31415926@126.com>
This commit is contained in:
Wang Chen
2023-06-17 09:24:16 +08:00
parent f77939f1e8
commit 6d2c046c67
9 changed files with 81 additions and 45 deletions
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14
code/os/03-contextswitch/entry.S
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@@ -1,12 +1,17 @@
# save all General-Purpose(GP) registers to context
# Save all General-Purpose(GP) registers to context.
# struct context *base = &ctx_task;
# base->ra = ra;
# ......
# These GP registers to be saved don't include gp
# and tp, because they are not caller-saved or
# callee-saved. These two registers are often used
# for special purpose. For example, in RVOS, 'tp'
# (aka "thread pointer") is used to store hartid,
# which is a global value and would not be changed
# during context-switch.
.macro reg_save base
sw ra, 0(\base)
sw sp, 4(\base)
sw gp, 8(\base)
sw tp, 12(\base)
sw t0, 16(\base)
sw t1, 20(\base)
sw t2, 24(\base)
@@ -39,14 +44,13 @@
.endm
# restore all General-Purpose(GP) registers from the context
# except gp & tp.
# struct context *base = &ctx_task;
# ra = base->ra;
# ......
.macro reg_restore base
lw ra, 0(\base)
lw sp, 4(\base)
lw gp, 8(\base)
lw tp, 12(\base)
lw t0, 16(\base)
lw t1, 20(\base)
lw t2, 24(\base)