From: sergos via Tarantool-patches <tarantool-patches@dev.tarantool.org> To: Sergey Kaplun <skaplun@tarantool.org> Cc: tarantool-patches@dev.tarantool.org Subject: Re: [Tarantool-patches] [PATCH luajit] Fix bytecode dump unpatching. Date: Mon, 27 Jun 2022 19:04:22 +0300 [thread overview] Message-ID: <60369E65-251D-4C39-B8BB-0EE3E291DC16@tarantool.org> (raw) In-Reply-To: <20220127115346.22800-1-skaplun@tarantool.org> Hi! Thanks for the patch! Just some nits in changelog, LGTM Sergos > On 27 Jan 2022, at 14:53, Sergey Kaplun <skaplun@tarantool.org> wrote: > > From: Mike Pall <mike> > > Reported by Christopher Oliver. > > (cherry picked from commit 20ac817a747cf8cab044ae81b09c08d23e34342b) > > When a compiled function with up-recursion RET bytecodes are patched to > JLOOP bytecode. If I got it right? “RET bytecodes are patched to JLOOP bytecode in a function with up-recursion." > During dump of those bytecodes they should be unpatched ^^^ ^^^^^ remove 2 words > to the original one. > It is done by restoring the opcode by subtraction > the diff between JLOOP and ILOOP bytecodes. That gives the LOOP > bytecodes instead RET as expected. The restore was done by the erroneous opcode subtraction, that led to a LOOP bytecode in place of the RET one. > This patch fixes the bytecode unpatching via copy the original start of ???? > instruction, that was patched. > > Sergey Kaplun: > * added the description and the test for the problem > > Part of tarantool/tarantool#6548 > --- > > Branch: https://github.com/tarantool/luajit/tree/skaplun/gh-noticket-wrong-bc-ret > Tarantool branch: https://github.com/tarantool/tarantool/tree/skaplun/gh-noticket-wrong-bc-ret-full-ci > Related issue: https://github.com/tarantool/tarantool/issues/6548 > > src/lj_bcwrite.c | 5 +---- > .../bc-jit-unpatching.test.lua | 22 +++++++++++++++++++ > 2 files changed, 23 insertions(+), 4 deletions(-) > create mode 100644 test/tarantool-tests/bc-jit-unpatching.test.lua > > diff --git a/src/lj_bcwrite.c b/src/lj_bcwrite.c > index 5e05caea..a86d6d00 100644 > --- a/src/lj_bcwrite.c > +++ b/src/lj_bcwrite.c > @@ -219,10 +219,7 @@ static char *bcwrite_bytecode(BCWriteCtx *ctx, char *p, GCproto *pt) > q[LJ_ENDIAN_SELECT(0, 3)] = (uint8_t)(op-BC_IFORL+BC_FORL); > } else if (op == BC_JFORL || op == BC_JITERL || op == BC_JLOOP) { > BCReg rd = q[LJ_ENDIAN_SELECT(2, 1)] + (q[LJ_ENDIAN_SELECT(3, 0)] << 8); > - BCIns ins = traceref(J, rd)->startins; > - q[LJ_ENDIAN_SELECT(0, 3)] = (uint8_t)(op-BC_JFORL+BC_FORL); > - q[LJ_ENDIAN_SELECT(2, 1)] = bc_c(ins); > - q[LJ_ENDIAN_SELECT(3, 0)] = bc_b(ins); > + memcpy(q, &traceref(J, rd)->startins, 4); > } > } > } > diff --git a/test/tarantool-tests/bc-jit-unpatching.test.lua b/test/tarantool-tests/bc-jit-unpatching.test.lua > new file mode 100644 > index 00000000..9f9cb390 > --- /dev/null > +++ b/test/tarantool-tests/bc-jit-unpatching.test.lua > @@ -0,0 +1,22 @@ > +local tap = require('tap') > +local utils = require('utils') > + > +local test = tap.test('bc-jit-unpatching') > +test:plan(1) > + > +-- Function with up-recursion. > +local function f(n) > + return n < 2 and n or f(n - 1) + f(n - 2) > +end > + > +local ret1bc = 'RET1%s*1%s*2' > +-- Check that this bytecode still persists. > +assert(utils.hasbc(loadstring(string.dump(f)), ret1bc)) > + > +-- Compile function to get JLOOP bytecode in recursion. Do you need any jit.opt.start(‘hotloop=1’) here? > +f(10) > + > +test:ok(utils.hasbc(loadstring(string.dump(f)), ret1bc), > + 'bytecode unpached correctly') > + > +os.exit(test:check() and 0 or 1) > -- > 2.34.1 >
next prev parent reply other threads:[~2022-06-27 16:04 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-01-27 11:53 Sergey Kaplun via Tarantool-patches 2022-06-27 16:04 ` sergos via Tarantool-patches [this message] 2022-06-28 6:57 ` Sergey Kaplun via Tarantool-patches 2022-06-28 9:12 ` Igor Munkin via Tarantool-patches 2022-06-30 12:10 ` Igor Munkin via Tarantool-patches
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