On Sat, Sep 14, 2019 at 03:08:10PM -0400, George Koehler wrote:
> On Thu, 12 Sep 2019 16:19:18 +0200
> Otto Moerbeek <[email protected]> wrote:
>
> > On Thu, Sep 12, 2019 at 12:54:47AM -0400, George Koehler wrote:
> > > The broken diff follows.
> >
> > The good news is that is is not broken for my use-case: PowerDNS
> > Recursor. It does not use ontop_fcontext. Thanks a lot for working on
> > this! I am wondering if there any users of ontop_fcontext in our tree...
> >
> > -Otto
>
> Here's a new diff with 3 more fixes:
>
> 1. It changes ontop_fcontext, so the fibonacci example now works.
>
> 2. It changes make_fcontext to align the stack pointer to 16 bytes.
> (Most code can run well or slightly slow with a 4-aligned stack
> pointer, but altivec vectors might cause a problem.)
>
> 3. Our patch-boost_context_pooled_fixedsize_stack_hpp used a wrong
> variable name, so any program that tried to #include
> <boost/context/pooled_fixedsize_stack.hpp> would get an error.
> The diff changes the variable name and bumps REVISION-main; this
> is the only part of the diff to affect arches other than powerpc.
>
> I have no code using pooled_fixedsize_stack, but one of the examples
> in boost includes the header via <boost/context/all.hpp>.
>
> I broke the fibonacci example because I caused ontop_fcontext to leave
> a stack frame, but didn't provide an .eh_frame for C++ exceptions.
> Then fibonacci threw an exception, but the unwinder can't remove the
> frame, so it didn't reach the code to catch the exception.
>
> To fix fibonacci, I go back to having ontop_fcontext make a tail call
> to the ontop-function without leaving a stack frame, like it does on
> Linux. I then cheat by placing an 8-byte transfer_t on the *other*
> stack; the existing code uses a similar cheat on Linux. This cheat
> will break if the program resumes the other stack before the
> ontop-function returns, but this is already broken on Linux.
>
> The diff doesn't fix 2 other bugs:
>
> 1. The handling of register %r13 is wrong, but this seems not to
> matter on OpenBSD, so I'm not trying to fix it.
>
> 2. The call to _exit(0) in make_fcontext is wrong for systems using
> the secure PLT, like OpenBSD. I have no code that reaches this
> call, but I would expect it to crash because it fails to set r30
> to the global offset table.
>
> I have stopped work on this diff. My next task is to report an issue
> to GitHub boost/context, about the multiple problems with ppc32.
This PowerDNS Recursor is still happy and the
boost_context_pooled_fixedsize_stack_hpp fix looks ok as well.
I'd say this is good to go in. Thanks,
-Otto
>
> Index: Makefile
> ===================================================================
> RCS file: /cvs/ports/devel/boost/Makefile,v
> retrieving revision 1.89
> diff -u -p -r1.89 Makefile
> --- Makefile 9 Aug 2019 11:25:29 -0000 1.89
> +++ Makefile 14 Sep 2019 00:56:15 -0000
> @@ -16,8 +16,8 @@ MASTER_SITES= ${MASTER_SITE_SOURCEFORGE:
> EXTRACT_SUFX= .tar.bz2
> FIX_EXTRACT_PERMISSIONS = Yes
>
> -REVISION-main= 6
> -REVISION-md= 1
> +REVISION-main= 7
> +REVISION-md= 2
>
> SO_VERSION= 9.0
> BOOST_LIBS= boost_atomic-mt \
> Index: patches/patch-boost_context_pooled_fixedsize_stack_hpp
> ===================================================================
> RCS file:
> /cvs/ports/devel/boost/patches/patch-boost_context_pooled_fixedsize_stack_hpp,v
> retrieving revision 1.1
> diff -u -p -r1.1 patch-boost_context_pooled_fixedsize_stack_hpp
> --- patches/patch-boost_context_pooled_fixedsize_stack_hpp 13 Dec 2018
> 19:52:46 -0000 1.1
> +++ patches/patch-boost_context_pooled_fixedsize_stack_hpp 14 Sep 2019
> 00:56:15 -0000
> @@ -18,7 +18,7 @@ Index: boost/context/pooled_fixedsize_st
> stack_context allocate() {
> - void * vp = storage_.malloc();
> - if ( ! vp) {
> -+ void * vp = mmap(NULL, size_, PROT_READ | PROT_WRITE,
> MAP_PRIVATE | MAP_ANON | MAP_STACK, -1, 0);
> ++ void * vp = mmap(NULL, stack_size_, PROT_READ | PROT_WRITE,
> MAP_PRIVATE | MAP_ANON | MAP_STACK, -1, 0);
> + if ( vp == MAP_FAILED ) {
> throw std::bad_alloc();
> }
> Index: patches/patch-libs_context_build_Jamfile_v2
> ===================================================================
> RCS file: patches/patch-libs_context_build_Jamfile_v2
> diff -N patches/patch-libs_context_build_Jamfile_v2
> --- /dev/null 1 Jan 1970 00:00:00 -0000
> +++ patches/patch-libs_context_build_Jamfile_v2 14 Sep 2019 00:56:15
> -0000
> @@ -0,0 +1,17 @@
> +$OpenBSD$
> +
> +ppc32_sysv_elf has 2 instances of "<toolset>clang".
> +The second "clang" should be "gcc".
> +
> +Index: libs/context/build/Jamfile.v2
> +--- libs/context/build/Jamfile.v2.orig
> ++++ libs/context/build/Jamfile.v2
> +@@ -326,7 +326,7 @@ alias asm_sources
> + <address-model>32
> + <architecture>power
> + <binary-format>elf
> +- <toolset>clang
> ++ <toolset>gcc
> + ;
> +
> + alias asm_sources
> Index: patches/patch-libs_context_src_asm_jump_ppc32_sysv_elf_gas_S
> ===================================================================
> RCS file: patches/patch-libs_context_src_asm_jump_ppc32_sysv_elf_gas_S
> diff -N patches/patch-libs_context_src_asm_jump_ppc32_sysv_elf_gas_S
> --- /dev/null 1 Jan 1970 00:00:00 -0000
> +++ patches/patch-libs_context_src_asm_jump_ppc32_sysv_elf_gas_S 14 Sep
> 2019 00:56:15 -0000
> @@ -0,0 +1,66 @@
> +$OpenBSD$
> +
> +ELF systems other than Linux use a different convention to return a
> +small struct like transfer_t.
> +
> +Index: libs/context/src/asm/jump_ppc32_sysv_elf_gas.S
> +--- libs/context/src/asm/jump_ppc32_sysv_elf_gas.S.orig
> ++++ libs/context/src/asm/jump_ppc32_sysv_elf_gas.S
> +@@ -78,6 +78,9 @@
> + .align 2
> + .type jump_fcontext,@function
> + jump_fcontext:
> ++ # Linux: jump_fcontext( hidden transfer_t * %r3, %r4, %r5)
> ++ # Other: transfer_t %r3:%r4 = jump_fcontext( %r3, %r4)
> ++
> + # reserve space on stack
> + subi %r1, %r1, 244
> +
> +@@ -121,7 +124,9 @@ jump_fcontext:
> + stw %r29, 216(%r1) # save R29
> + stw %r30, 220(%r1) # save R30
> + stw %r31, 224(%r1) # save R31
> ++#ifdef __Linux__
> + stw %r3, 228(%r1) # save hidden
> ++#endif
> +
> + # save CR
> + mfcr %r0
> +@@ -135,8 +140,12 @@ jump_fcontext:
> + # store RSP (pointing to context-data) in R6
> + mr %r6, %r1
> +
> +- # restore RSP (pointing to context-data) from R4
> ++ # restore RSP (pointing to context-data) from R4/R3
> ++#ifdef __Linux__
> + mr %r1, %r4
> ++#else
> ++ mr %r1, %r3
> ++#endif
> +
> + lfd %f14, 0(%r1) # restore F14
> + lfd %f15, 8(%r1) # restore F15
> +@@ -178,7 +187,9 @@ jump_fcontext:
> + lwz %r29, 216(%r1) # restore R29
> + lwz %r30, 220(%r1) # restore R30
> + lwz %r31, 224(%r1) # restore R31
> ++#ifdef __Linux__
> + lwz %r3, 228(%r1) # restore hidden
> ++#endif
> +
> + # restore CR
> + lwz %r0, 232(%r1)
> +@@ -195,8 +206,13 @@ jump_fcontext:
> + addi %r1, %r1, 244
> +
> + # return transfer_t
> ++#ifdef __Linux__
> + stw %r6, 0(%r3)
> + stw %r5, 4(%r3)
> ++#else
> ++ mr %r3, %r6
> ++ # %r4, %r4
> ++#endif
> +
> + # jump to context
> + bctr
> Index: patches/patch-libs_context_src_asm_make_ppc32_sysv_elf_gas_S
> ===================================================================
> RCS file: patches/patch-libs_context_src_asm_make_ppc32_sysv_elf_gas_S
> diff -N patches/patch-libs_context_src_asm_make_ppc32_sysv_elf_gas_S
> --- /dev/null 1 Jan 1970 00:00:00 -0000
> +++ patches/patch-libs_context_src_asm_make_ppc32_sysv_elf_gas_S 14 Sep
> 2019 00:56:15 -0000
> @@ -0,0 +1,78 @@
> +$OpenBSD$
> +
> +Stack should have alignment 16 after jump_fcontext drops 244 bytes.
> +
> +ELF systems other than Linux use a different convention to return a
> +small struct like transfer_t.
> +
> +Index: libs/context/src/asm/make_ppc32_sysv_elf_gas.S
> +--- libs/context/src/asm/make_ppc32_sysv_elf_gas.S.orig
> ++++ libs/context/src/asm/make_ppc32_sysv_elf_gas.S
> +@@ -85,12 +85,19 @@ make_fcontext:
> + # shift address in R3 to lower 16 byte boundary
> + clrrwi %r3, %r3, 4
> +
> +- # reserve space for context-data on context-stack
> +- # including 64 byte of linkage + parameter area (R1 % 16 == 0)
> +- subi %r3, %r3, 336
> ++ # reserve space on context-stack, including 16 bytes of linkage
> ++ # and parameter area + 244 bytes of context-data; jump_fcontext
> ++ # will drop 244 bytes to align the stack (244 % 16 != 0)
> ++ subi %r3, %r3, 16 + 244
> +
> + # third arg of make_fcontext() == address of context-function
> ++#ifdef __Linux__
> ++ # save context-function as PC
> + stw %r5, 240(%r3)
> ++#else
> ++ # save context-function for trampoline
> ++ stw %r5, 252(%r3)
> ++#endif
> +
> + # set back-chain to zero
> + li %r0, 0
> +@@ -99,10 +106,12 @@ make_fcontext:
> + mffs %f0 # load FPSCR
> + stfd %f0, 144(%r3) # save FPSCR
> +
> ++#ifdef __Linux__
> + # compute address of returned transfer_t
> + addi %r0, %r3, 252
> + mr %r4, %r0
> + stw %r4, 228(%r3)
> ++#endif
> +
> + # load LR
> + mflr %r0
> +@@ -111,6 +120,11 @@ make_fcontext:
> + 1:
> + # load LR into R4
> + mflr %r4
> ++#ifndef __Linux__
> ++ # compute abs address of trampoline; use as PC
> ++ addi %r7, %r4, trampoline - 1b
> ++ stw %r7, 240(%r3)
> ++#endif
> + # compute abs address of label finish
> + addi %r4, %r4, finish - 1b
> + # restore LR
> +@@ -123,6 +137,19 @@ make_fcontext:
> + mtlr %r6
> +
> + blr # return pointer to context-data
> ++
> ++#ifndef __Linux__
> ++trampoline:
> ++ # On systems other than Linux, jump_fcontext is returning the
> ++ # transfer_t in %r3:%r4, but we need to pass transfer_t * %r3 to
> ++ # our context-function.
> ++ lwz %r0, 8(%r1) # address of context-function
> ++ mtctr %r0
> ++ stw %r3, 8(%r1)
> ++ stw %r4, 12(%r1) # move transfer_t to stack
> ++ la %r3, 8(%r1) # address of transfer_t
> ++ bctr
> ++#endif
> +
> + finish:
> + # save return address into R0
> Index: patches/patch-libs_context_src_asm_ontop_ppc32_sysv_elf_gas_S
> ===================================================================
> RCS file: patches/patch-libs_context_src_asm_ontop_ppc32_sysv_elf_gas_S
> diff -N patches/patch-libs_context_src_asm_ontop_ppc32_sysv_elf_gas_S
> --- /dev/null 1 Jan 1970 00:00:00 -0000
> +++ patches/patch-libs_context_src_asm_ontop_ppc32_sysv_elf_gas_S 14 Sep
> 2019 00:56:15 -0000
> @@ -0,0 +1,75 @@
> +$OpenBSD$
> +
> +ELF systems other than Linux use a different convention to return a
> +small struct like transfer_t.
> +
> +Index: libs/context/src/asm/ontop_ppc32_sysv_elf_gas.S
> +--- libs/context/src/asm/ontop_ppc32_sysv_elf_gas.S.orig
> ++++ libs/context/src/asm/ontop_ppc32_sysv_elf_gas.S
> +@@ -78,6 +78,9 @@
> + .align 2
> + .type ontop_fcontext,@function
> + ontop_fcontext:
> ++ # Linux: ontop_fcontext( hidden transfer_t * %r3, %r4, %r5, %r6)
> ++ # Other: transfer_t %r3:%r4 = ontop_fcontext( %r3, %r4, %r5)
> ++
> + # reserve space on stack
> + subi %r1, %r1, 244
> +
> +@@ -121,7 +124,9 @@ ontop_fcontext:
> + stw %r29, 216(%r1) # save R29
> + stw %r30, 220(%r1) # save R30
> + stw %r31, 224(%r1) # save R31
> ++#ifdef __Linux__
> + stw %r3, 228(%r1) # save hidden
> ++#endif
> +
> + # save CR
> + mfcr %r0
> +@@ -135,8 +140,12 @@ ontop_fcontext:
> + # store RSP (pointing to context-data) in R7
> + mr %r7, %r1
> +
> +- # restore RSP (pointing to context-data) from R4
> ++ # restore RSP (pointing to context-data) from R4/R3
> ++#ifdef __Linux__
> + mr %r1, %r4
> ++#else
> ++ mr %r1, %r3
> ++#endif
> +
> + lfd %f14, 0(%r1) # restore F14
> + lfd %f15, 8(%r1) # restore F15
> +@@ -178,7 +187,9 @@ ontop_fcontext:
> + lwz %r29, 216(%r1) # restore R29
> + lwz %r30, 220(%r1) # restore R30
> + lwz %r31, 224(%r1) # restore R31
> ++#ifdef __Linux__
> + lwz %r4, 228(%r1) # restore hidden
> ++#endif
> +
> + # restore CR
> + lwz %r0, 232(%r1)
> +@@ -191,12 +202,22 @@ ontop_fcontext:
> + # adjust stack
> + addi %r1, %r1, 244
> +
> ++#ifdef __Linux__
> + # return transfer_t
> + stw %r7, 0(%r4)
> + stw %r5, 4(%r4)
> +
> + # restore CTR
> + mtctr %r6
> ++#else
> ++ # On systems other than Linux, we allocate a transfer_t on the
> ++ # other stack, below its stack pointer %r7.
> ++ stw %r7, -8(%r7)
> ++ stw %r4, -4(%r7)
> ++ la %r3, -8(%r7) # address of transfer_t
> ++
> ++ mtctr %r5
> ++#endif
> +
> + # jump to ontop-function
> + bctr
>
