Chiebot-Mirror/boringssl - boringssl - Gitea: Git with a cup of tea

Author	SHA1	Message	Date
Adam Langley	0cd846f24f	delocation: large memory model support. Large memory models on x86-64 allow the code/data of a shared object / executable to be larger than 2GiB. This is typically impossible because x86-64 code frequently uses int32 offsets from RIP. Consider the following program: int getpid(); int main() { return getpid(); } This is turned into the following assembly under a large memory model: .L0$pb: leaq .L0$pb(%rip), %rax movabsq $_GLOBAL_OFFSET_TABLE_-.L0$pb, %rcx addq %rax, %rcx movabsq $getpid@GOT, %rdx xorl %eax, %eax jmpq (%rcx,%rdx) # TAILCALL And, with relocations: 0: 48 8d 05 f9 ff ff ff lea -0x7(%rip),%rax # 0 <main> 7: 48 b9 00 00 00 00 00 movabs $0x0,%rcx e: 00 00 00 9: R_X86_64_GOTPC64 _GLOBAL_OFFSET_TABLE_+0x9 11: 48 01 c1 add %rax,%rcx 14: 48 ba 00 00 00 00 00 movabs $0x0,%rdx 1b: 00 00 00 16: R_X86_64_GOT64 getpid 1e: 31 c0 xor %eax,%eax 20: ff 24 11 jmpq (%rcx,%rdx,1) We can see that, in the large memory model, function calls involve loading the address of _GLOBAL_OFFSET_TABLE_ (using `movabs`, which takes a 64-bit immediate) and then indexing into it. Both cause relocations. If we link the binary and disassemble we get: 0000000000001120 <main>: 1120: 48 8d 05 f9 ff ff ff lea -0x7(%rip),%rax # 1120 <main> 1127: 48 b9 e0 2e 00 00 00 movabs $0x2ee0,%rcx 112e: 00 00 00 1131: 48 01 c1 add %rax,%rcx 1134: 48 ba d8 ff ff ff ff movabs $0xffffffffffffffd8,%rdx 113b: ff ff ff 113e: 31 c0 xor %eax,%eax 1140: ff 24 11 jmpq (%rcx,%rdx,1) Thus the _GLOBAL_OFFSET_TABLE_ symbol is at 0x1120+0x2ee0 = 0x4000. That's the address of the .got.plt section. But the offset “into” the table is -0x40, putting it at 0x3fd8, in .got: Idx Name Size VMA LMA File off Algn 18 .got 00000030 0000000000003fd0 0000000000003fd0 00002fd0 23 19 .got.plt 00000018 0000000000004000 0000000000004000 00003000 2*3 And, indeed, there's a dynamic relocation to setup that address: OFFSET TYPE VALUE 0000000000003fd8 R_X86_64_GLOB_DAT getpid@GLIBC_2.2.5 Accessing data or BSS works the same: the address of the variable is stored relative to _GLOBAL_OFFSET_TABLE_. This is a bit of a pain because we want to delocate the module into a single .text segment so that it moves through linking unaltered. If we took the obvious path and built our own offset table then it would need to contain absolute addresses, but they are only available at runtime and .text segments aren't supposed to be run-time patched. (That's why .rela.dyn is a separate segment.) If we use a different segment then we have the same problem as with the original offset table: the offset to the segment is unknown when compiling the module. Trying to pattern match this two-step lookup to do extensive rewriting seems fragile: I'm sure the compilers will move things around and interleave other work in time, if they don't already. So, in order to handle movabs trying to load _GLOBAL_OFFSET_TABLE_ we define a symbol in the same segment, but outside of the hashed region of the module, that contains the offset from that position to _GLOBAL_OFFSET_TABLE_: .boringssl_got_delta: .quad _GLOBAL_OFFSET_TABLE_-.boringssl_got_delta Then a movabs of $_GLOBAL_OFFSET_TABLE_-.Lfoo turns into: movq .boringssl_got_delta(%rip), %destreg addq $.boringssl_got_delta-.Lfoo, %destreg This works because it's calculating _GLOBAL_OFFSET_TABLE_ - got_delta + (got_delta - .Lfoo) When that value is added to .Lfoo, as the original code will do, the correct address results. Also it doesn't need an extra register because we know that 32-bit offsets are sufficient for offsets within the module. As for the offsets within the offset table, we have to load them from locations outside of the hashed part of the module to get the relocations out of the way. Again, no extra registers are needed. Change-Id: I87b19a2f8886bd9f7ac538fd55754e526bcf3097 Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/42324 Reviewed-by: Adam Langley <agl@google.com> Commit-Queue: Adam Langley <agl@google.com>	5 years ago
Daniel McArdle	1a63507c41	Add line number to doc.go error messages. Change-Id: I00f35648a6d354abdc908314fef48b3fa573d825 Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/42224 Commit-Queue: David Benjamin <davidben@google.com> Reviewed-by: David Benjamin <davidben@google.com>	5 years ago
Adam Langley	f0558c359c	Kick the bots. This should make them update and generate JSON outputs due to `8c0a6ebfc2`. Change-Id: I7e2fa7ace2ed0216fee6b553c4cf7e16a7d7457d	5 years ago
David Benjamin	8c0a6ebfc2	Add a JSON output to generate_build_files.py. gRPC are currently importing generate_build_files.py, injecting a custom printer, and running into problems with the symlinks they set up to make this work, as well as needing to delete duplicate generated files. `53a5ad34c0/src/boringssl/gen_build_yaml.py (L130)` https://boringssl-review.googlesource.com/c/boringssl/+/42164 Rather than layer on more hacks, add a JSON output to generate_build_files.py. This outputs a sources.json file that folks with especially custom builds can consume. (Looks like gRPC converts to some home-grown YAML format which I imagine is further processed by some other generator?) We can then add it to master-with-bazel's output. Change-Id: I82b4ea0647386ca6c76a977f057b9962f40d41c8 Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/42204 Reviewed-by: Adam Langley <agl@google.com>	5 years ago
David Benjamin	8f88b27d6a	Link to ws2_32 more consistently. This fixes a couple issues: - Which libraries to use should be based on WIN32, not MSVC. - Windows libraries can be specified by #pragma comment lines in the source or by build dependencies. We specified #pragma lines in source, but also have build dependencies in crypto_test, etc. The latter was missing bssl. The comment line should be sufficient, but being explicit is useful, so fill in the missing one. This should help building with MINGW, which is missing support for the usual Windows pragma. Change-Id: Ide9328c7dd306738ebbb0792e47da96948fe12f4 Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/42105 Commit-Queue: Adam Langley <agl@google.com> Reviewed-by: Adam Langley <agl@google.com>	5 years ago
Adam Langley	fb0c05cac2	acvp: add CMAC-AES support. Change by Dan Janni. Change-Id: I3f059e7b1a822c6f97128ca92a693499a3f7fa8f Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/41984 Commit-Queue: Adam Langley <agl@google.com> Reviewed-by: David Benjamin <davidben@google.com>	5 years ago

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