Author: Armin Rigo <ar...@tunes.org>
Branch: stmgc-c7
Changeset: r70266:31386d1544cb
Date: 2014-03-24 21:47 +0100
http://bitbucket.org/pypy/pypy/changeset/31386d1544cb/
Log: Fix
diff --git a/rpython/jit/backend/x86/assembler.py
b/rpython/jit/backend/x86/assembler.py
--- a/rpython/jit/backend/x86/assembler.py
+++ b/rpython/jit/backend/x86/assembler.py
@@ -157,8 +157,12 @@
gcrootmap = self.cpu.gc_ll_descr.gcrootmap
if gcrootmap and gcrootmap.is_shadow_stack:
- self._load_shadowstack_top_in_ebx(mc, gcrootmap)
+ mc.MOV(ebx, self.heap_shadowstack_top())
mc.MOV_mr((self.SEGMENT_NO, ebx.value, -WORD), eax.value)
+ # STM note: this stores the updated jitframe object in the
+ # position -WORD, but (in this case) leaves the position
+ # -2*WORD untouched. This old jitframe object remains in
+ # the shadowstack just in case we do an abort later.
mc.MOV_bi((self.SEGMENT_FRAME, gcmap_ofs), 0)
self._pop_all_regs_from_frame(mc, [], self.cpu.supports_floats)
@@ -771,7 +775,7 @@
gcrootmap = self.cpu.gc_ll_descr.gcrootmap
if gcrootmap and gcrootmap.is_shadow_stack:
- self._call_header_shadowstack(gcrootmap)
+ self._call_header_shadowstack()
def _call_header_with_stack_check(self):
self._call_header()
@@ -801,13 +805,9 @@
# we called a pypy_stm_start_transaction() earlier.
assert IS_X86_64
#
- # load the shadowstack pointer into ebx, and decrement it,
- # but don't decrement the official shadowstack yet! We just
- # keep it in ebx for a while (a callee-saved register).
+ # load the shadowstack pointer into ebx (a callee-saved register)
mc = self.mc
- rst = self.heap_tl(gcrootmap.get_root_stack_top_addr())
- mc.MOV(ebx, rst)
- mc.SUB_ri(ebx.value, WORD)
+ mc.MOV(ebx, self.heap_shadowstack_top())
# load the address of the jmpbuf
mc.LEA_rs(edi.value, STM_JMPBUF_OFS)
# compare it with the currently-stored jmpbuf
@@ -821,18 +821,20 @@
mc.CALL(imm(rstm.adr__stm_become_inevitable))
# there could have been a collection in _stm_become_inevitable;
# reload the frame into ebp
- mc.MOV_rm(ebp.value, (self.SEGMENT_NO, ebx.value, 0))
+ mc.MOV_rm(ebp.value, (self.SEGMENT_NO, ebx.value, -WORD))
#
# this is where the JNE above jumps
offset = mc.get_relative_pos() - jne_location
assert 0 < offset <= 127
mc.overwrite(jne_location-1, chr(offset))
#
- # now store ebx back, which will really decrement the shadowstack
- mc.MOV(rst, ebx)
+ # now decrement ebx by 2*WORD and store it back, which will
+ # really decrement the shadowstack
+ mc.SUB_ri(ebx.value, 2 * WORD)
+ mc.MOV(self.heap_shadowstack_top(), ebx)
elif gcrootmap and gcrootmap.is_shadow_stack:
- self._call_footer_shadowstack(gcrootmap)
+ self._call_footer_shadowstack()
# the return value is the jitframe
self.mc.MOV_rr(eax.value, ebp.value)
@@ -845,26 +847,37 @@
self.mc.ADD_ri(esp.value, self._get_whole_frame_size() * WORD)
self.mc.RET()
- def _load_shadowstack_top_in_ebx(self, mc, gcrootmap):
- """Loads the shadowstack top in ebx, and returns an integer
- that gives the address of the stack top.
- """
- mc.MOV(ebx, self.heap_tl(gcrootmap.get_root_stack_top_addr()))
+ def heap_shadowstack_top(self):
+ """Return an AddressLoc for '&shadowstack', the shadow stack top."""
+ gcrootmap = self.cpu.gc_ll_descr.gcrootmap
+ return self.heap_tl(gcrootmap.get_root_stack_top_addr())
- def _call_header_shadowstack(self, gcrootmap):
+ def _call_header_shadowstack(self):
# put the frame in ebp on the shadowstack for the GC to find
# (ebp is a writeable object and does not need a write-barrier
# again (ensured by the code calling the loop))
- self._load_shadowstack_top_in_ebx(self.mc, gcrootmap)
+ self.mc.MOV(ebx, self.heap_shadowstack_top())
self.mc.MOV_mr((self.SEGMENT_NO, ebx.value, 0), ebp.value)
# MOV [ebx], ebp
- self.mc.ADD_ri(ebx.value, WORD)
- self.mc.MOV(self.heap_tl(gcrootmap.get_root_stack_top_addr()), ebx)
- # MOV [rootstacktop], ebx
+ if self.cpu.gc_ll_descr.stm:
+ # With stm, we push the jitframe twice on the shadowstack.
+ # If we break transaction inside this frame, we'll do it
+ # with only one item on the shadowstack, and then we'll
+ # duplicate it again. The point is to store both the
+ # old and the new copy when case we do a realloc_frame,
+ # just for the case where we later abort.
+ self.mc.MOV_mr((self.SEGMENT_NO, ebx.value, WORD), ebp.value)
+ self.mc.ADD_ri(ebx.value, 2 * WORD)
+ else:
+ self.mc.ADD_ri(ebx.value, WORD)
+ self.mc.MOV(self.heap_shadowstack_top(), ebx) # MOV [rootstacktop], ebx
- def _call_footer_shadowstack(self, gcrootmap):
- self.mc.SUB(self.heap_tl(gcrootmap.get_root_stack_top_addr()), WORD)
- # SUB [rootstacktop], WORD
+ def _call_footer_shadowstack(self):
+ # SUB [rootstacktop], WORD (or 2 * WORD with STM)
+ if self.cpu.gc_ll_descr.stm:
+ self.mc.SUB(self.heap_shadowstack_top(), 2 * WORD)
+ else:
+ self.mc.SUB(self.heap_shadowstack_top(), WORD)
def redirect_call_assembler(self, oldlooptoken, newlooptoken):
# some minimal sanity checking
@@ -1133,9 +1146,12 @@
gcrootmap = self.cpu.gc_ll_descr.gcrootmap
if gcrootmap:
if gcrootmap.is_shadow_stack:
- mc.MOV(ecx, self.heap_tl(gcrootmap.get_root_stack_top_addr()))
+ mc.MOV(ecx, self.heap_shadowstack_top())
mc.MOV(ebp, mem(self.SEGMENT_NO, ecx, -WORD))
- #
+ self._reload_frame_wb(mc, align_stack)
+
+ def _reload_frame_wb(self, mc, align_stack=False):
+ gcrootmap = self.cpu.gc_ll_descr.gcrootmap
wbdescr = self.cpu.gc_ll_descr.write_barrier_descr
if gcrootmap and wbdescr:
# frame never uses card marking, so we enforce this is not
@@ -2535,6 +2551,12 @@
# call stm_commit_transaction()
mc.CALL(imm(rstm.adr_stm_commit_transaction))
#
+ # copy shadowstack[-1] into shadowstack[-2]: the latter is
+ # not going to be used any more, now that we committed
+ mc.MOV(ebx, self.heap_shadowstack_top())
+ mc.MOV_rm(eax.value, (self.SEGMENT_NO, ebx, -WORD))
+ mc.MOV_mr((self.SEGMENT_NO, ebx, -2 * WORD), eax.value)
+ #
# update the two words in the STM_RESUME_BUF, as described
# in arch.py. The "learip" pseudo-instruction turns into
# what is, in gnu as syntax: lea 0(%rip), %rax (the 0 is
@@ -2561,8 +2583,13 @@
mc.LEA_rs(esi.value, STM_JMPBUF_OFS_RBP)
mc.CALL(imm(rstm.adr_pypy_stm_start_transaction))
#
- # reload ebp with the frame now
- self._reload_frame_if_necessary(self.mc)
+ # reload ebp with the frame now, picking the value from
+ # shadowstack[-2] and duplicating it into shadowstack[-1].
+ # Only realloc_frame can make these values different again.
+ mc.MOV(ebx, self.heap_shadowstack_top())
+ mc.MOV_rm(ebp.value, (self.SEGMENT_NO, ebx, -2 * WORD))
+ mc.MOV_mr((self.SEGMENT_NO, ebx, -WORD), ebp.value)
+ self._reload_frame_wb(self.mc)
#
# restore regs
self._push_pop_regs_to_frame(False, mc, grp_regs, xmm_regs)
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