From 396e486a3bb379d34d89e1f868b1ebccdc4f4a31 Mon Sep 17 00:00:00 2001 From: Khem Raj Date: Sat, 10 Aug 2019 02:41:22 -0700 Subject: busybox: Update the clang compatibility patch to work with clang 9.x Signed-off-by: Khem Raj --- ...r_to_globals-and-bb_errno-to-be-non-const.patch | 137 +++++++++++++++++++++ ...a-const-variable-is-undefined-behavior-C9.patch | 27 ---- recipes-core/busybox/busybox_%.bbappend | 5 +- 3 files changed, 141 insertions(+), 28 deletions(-) create mode 100644 recipes-core/busybox/busybox/0001-Turn-ptr_to_globals-and-bb_errno-to-be-non-const.patch delete mode 100644 recipes-core/busybox/busybox/0001-writing-to-a-const-variable-is-undefined-behavior-C9.patch diff --git a/recipes-core/busybox/busybox/0001-Turn-ptr_to_globals-and-bb_errno-to-be-non-const.patch b/recipes-core/busybox/busybox/0001-Turn-ptr_to_globals-and-bb_errno-to-be-non-const.patch new file mode 100644 index 0000000..481b125 --- /dev/null +++ b/recipes-core/busybox/busybox/0001-Turn-ptr_to_globals-and-bb_errno-to-be-non-const.patch @@ -0,0 +1,137 @@ +From c7580fdb4be69a872291ccf22334091cace749fc Mon Sep 17 00:00:00 2001 +From: Khem Raj +Date: Wed, 16 Jan 2019 22:39:24 -0800 +Subject: [PATCH] Turn ptr_to_globals and bb_errno to be non const + +writing to a const variable is undefined behavior + +This is undefined as per (C99 6.7.3 paragraph 5) see [1] + +errno and ptr_to_globals is written to in code, this fails with +segfaults when compiled with clang + +unsigned FAST_FUNC bb_strtou(const char *arg, char **endp, int base) +{ + unsigned long v; + char *endptr; + + if (!endp) endp = &endptr; + *endp = (char*) arg; + + if (!isalnum(arg[0])) return ret_ERANGE(); + errno = 0; + v = strtoul(arg, endp, base); + if (v > UINT_MAX) return ret_ERANGE(); + return handle_errors(v, endp); + } + +without 'const' ( working code ) + +Dump of assembler code for function bb_strtou: + 0x0000555555568298 <+0>: push %rbx + 0x0000555555568299 <+1>: sub $0x10,%rsp + 0x000055555556829d <+5>: test %rsi,%rsi + 0x00005555555682a0 <+8>: lea 0x8(%rsp),%rbx + 0x00005555555682a5 <+13>: cmovne %rsi,%rbx + 0x00005555555682a9 <+17>: mov %rdi,(%rbx) + 0x00005555555682ac <+20>: mov (%rdi),%al + 0x00005555555682ae <+22>: lea -0x30(%rax),%ecx + 0x00005555555682b1 <+25>: cmp $0xa,%cl + 0x00005555555682b4 <+28>: jb 0x5555555682be + 0x00005555555682b6 <+30>: or $0x20,%al + 0x00005555555682b8 <+32>: add $0x9f,%al + 0x00005555555682ba <+34>: cmp $0x1a,%al + 0x00005555555682bc <+36>: jae 0x5555555682dc + 0x00005555555682be <+38>: mov 0x107da3(%rip),%rax # 0x555555670068 +=> 0x00005555555682c5 <+45>: movl $0x0,(%rax) + 0x00005555555682cb <+51>: mov %rbx,%rsi + 0x00005555555682ce <+54>: callq 0x555555564310 + 0x00005555555682d3 <+59>: mov %rax,%rcx + 0x00005555555682d6 <+62>: shr $0x20,%rcx + 0x00005555555682da <+66>: je 0x5555555682f0 + 0x00005555555682dc <+68>: mov 0x107d85(%rip),%rax # 0x555555670068 + 0x00005555555682e3 <+75>: movl $0x22,(%rax) + 0x00005555555682e9 <+81>: mov $0xffffffff,%eax + 0x00005555555682ee <+86>: jmp 0x5555555682fb + 0x00005555555682f0 <+88>: mov %rax,%rdi + 0x00005555555682f3 <+91>: mov %rbx,%rsi + 0x00005555555682f6 <+94>: callq 0x5555555681e8 + 0x00005555555682fb <+99>: add $0x10,%rsp + 0x00005555555682ff <+103>: pop %rbx + 0x0000555555568300 <+104>: retq + +here address of bb_errno is valid rax = 0x7ffff7cac6c0 + +with 'const' ( non-working code ) + +Dump of assembler code for function bb_strtou: + 0x00005555555682a4 <+0>: push %r14 + 0x00005555555682a6 <+2>: push %rbx + 0x00005555555682a7 <+3>: push %rax + 0x00005555555682a8 <+4>: test %rsi,%rsi + 0x00005555555682ab <+7>: mov %rsp,%rbx + 0x00005555555682ae <+10>: cmovne %rsi,%rbx + 0x00005555555682b2 <+14>: mov %rdi,(%rbx) + 0x00005555555682b5 <+17>: mov (%rdi),%al + 0x00005555555682b7 <+19>: lea -0x30(%rax),%ecx + 0x00005555555682ba <+22>: cmp $0xa,%cl + 0x00005555555682bd <+25>: jb 0x5555555682d6 + 0x00005555555682bf <+27>: or $0x20,%al + 0x00005555555682c1 <+29>: add $0x9f,%al + 0x00005555555682c3 <+31>: cmp $0x1a,%al + 0x00005555555682c5 <+33>: jb 0x5555555682d6 + 0x00005555555682c7 <+35>: mov 0x107d9a(%rip),%rax # 0x555555670068 + 0x00005555555682ce <+42>: movl $0x22,(%rax) + 0x00005555555682d4 <+48>: jmp 0x5555555682fc + 0x00005555555682d6 <+50>: mov 0x107d8b(%rip),%r14 # 0x555555670068 +=> 0x00005555555682dd <+57>: movl $0x0,(%r14) + 0x00005555555682e4 <+64>: mov %rbx,%rsi + 0x00005555555682e7 <+67>: callq 0x555555564300 + 0x00005555555682ec <+72>: mov %rax,%rcx + 0x00005555555682ef <+75>: shr $0x20,%rcx + 0x00005555555682f3 <+79>: je 0x555555568303 + 0x00005555555682f5 <+81>: movl $0x22,(%r14) + 0x00005555555682fc <+88>: mov $0xffffffff,%eax + 0x0000555555568301 <+93>: jmp 0x55555556830e + 0x0000555555568303 <+95>: mov %rax,%rdi + 0x0000555555568306 <+98>: mov %rbx,%rsi + 0x0000555555568309 <+101>: callq 0x5555555681f4 + 0x000055555556830e <+106>: add $0x8,%rsp + 0x0000555555568312 <+110>: pop %rbx + 0x0000555555568313 <+111>: pop %r14 + 0x0000555555568315 <+113>: retq + +r14 is 0x0 and writing to this ofcourse ends up in segfault + +[1] https://bugs.llvm.org/show_bug.cgi?id=39919 + +Signed-off-by: Khem Raj +--- + include/libbb.h | 4 ++-- + 1 file changed, 2 insertions(+), 2 deletions(-) + +diff --git a/include/libbb.h b/include/libbb.h +index 111d1b790..a52265e77 100644 +--- a/include/libbb.h ++++ b/include/libbb.h +@@ -341,7 +341,7 @@ struct BUG_off_t_size_is_misdetected { + #if defined(__GLIBC__) + /* glibc uses __errno_location() to get a ptr to errno */ + /* We can just memorize it once - no multithreading in busybox :) */ +-extern int *const bb_errno; ++extern int *bb_errno; + #undef errno + #define errno (*bb_errno) + #endif +@@ -2152,7 +2152,7 @@ struct globals; + /* '*const' ptr makes gcc optimize code much better. + * Magic prevents ptr_to_globals from going into rodata. + * If you want to assign a value, use SET_PTR_TO_GLOBALS(x) */ +-extern struct globals *const ptr_to_globals; ++extern struct globals *ptr_to_globals; + /* At least gcc 3.4.6 on mipsel system needs optimization barrier */ + #define barrier() __asm__ __volatile__("":::"memory") + #define SET_PTR_TO_GLOBALS(x) do { \ +-- +2.22.0 + diff --git a/recipes-core/busybox/busybox/0001-writing-to-a-const-variable-is-undefined-behavior-C9.patch b/recipes-core/busybox/busybox/0001-writing-to-a-const-variable-is-undefined-behavior-C9.patch deleted file mode 100644 index 6b933da..0000000 --- a/recipes-core/busybox/busybox/0001-writing-to-a-const-variable-is-undefined-behavior-C9.patch +++ /dev/null @@ -1,27 +0,0 @@ -From 64c27d12dab4d5a31103f48773733f17c84b0a77 Mon Sep 17 00:00:00 2001 -From: Khem Raj -Date: Wed, 16 Jan 2019 22:39:24 -0800 -Subject: [PATCH] writing to a const variable is undefined behavior (C99 6.7.3 - paragraph 5). - -Signed-off-by: Khem Raj ---- - include/libbb.h | 2 +- - 1 file changed, 1 insertion(+), 1 deletion(-) - -diff --git a/include/libbb.h b/include/libbb.h -index 3366df30f..6b925eb2d 100644 ---- a/include/libbb.h -+++ b/include/libbb.h -@@ -2092,7 +2092,7 @@ struct globals; - /* '*const' ptr makes gcc optimize code much better. - * Magic prevents ptr_to_globals from going into rodata. - * If you want to assign a value, use SET_PTR_TO_GLOBALS(x) */ --extern struct globals *const ptr_to_globals; -+extern struct globals *ptr_to_globals; - /* At least gcc 3.4.6 on mipsel system needs optimization barrier */ - #define barrier() __asm__ __volatile__("":::"memory") - #define SET_PTR_TO_GLOBALS(x) do { \ --- -2.20.1 - diff --git a/recipes-core/busybox/busybox_%.bbappend b/recipes-core/busybox/busybox_%.bbappend index a4c90f4..2187660 100644 --- a/recipes-core/busybox/busybox_%.bbappend +++ b/recipes-core/busybox/busybox_%.bbappend @@ -1,3 +1,6 @@ FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:" -SRC_URI_append_toolchain-clang = " file://0001-writing-to-a-const-variable-is-undefined-behavior-C9.patch" +SRC_URI_append_toolchain-clang = "\ + file://0001-Turn-ptr_to_globals-and-bb_errno-to-be-non-const.patch \ + " + TOOLCHAIN_x86 = "gcc" -- cgit v1.2.3-54-g00ecf