From 73bbb94466fd3f8b313eeb0b0467314a262dddb3 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Mon, 5 Apr 2021 04:58:39 +0200 Subject: kallsyms: support "big" kernel symbols Rust symbols can become quite long due to namespacing introduced by modules, types, traits, generics, etc. Increasing to 255 is not enough in some cases, therefore introduce longer lengths to the symbol table. In order to avoid increasing all lengths to 2 bytes (since most of them are small, including many Rust ones), use ULEB128 to keep smaller symbols in 1 byte, with the rest in 2 bytes. Reviewed-by: Kees Cook Reviewed-by: Greg Kroah-Hartman Co-developed-by: Alex Gaynor Signed-off-by: Alex Gaynor Co-developed-by: Wedson Almeida Filho Signed-off-by: Wedson Almeida Filho Co-developed-by: Gary Guo Signed-off-by: Gary Guo Co-developed-by: Boqun Feng Signed-off-by: Boqun Feng Co-developed-by: Matthew Wilcox Signed-off-by: Matthew Wilcox Signed-off-by: Miguel Ojeda --- kernel/kallsyms.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index 3e7e2c2ad2f7..fc5e26348d25 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -50,12 +50,20 @@ static unsigned int kallsyms_expand_symbol(unsigned int off, data = &kallsyms_names[off]; len = *data; data++; + off++; + + /* If MSB is 1, it is a "big" symbol, so needs an additional byte. */ + if ((len & 0x80) != 0) { + len = (len & 0x7F) | (*data << 7); + data++; + off++; + } /* * Update the offset to return the offset for the next symbol on * the compressed stream. */ - off += len + 1; + off += len; /* * For every byte on the compressed symbol data, copy the table @@ -108,7 +116,7 @@ static char kallsyms_get_symbol_type(unsigned int off) static unsigned int get_symbol_offset(unsigned long pos) { const u8 *name; - int i; + int i, len; /* * Use the closest marker we have. We have markers every 256 positions, @@ -122,8 +130,18 @@ static unsigned int get_symbol_offset(unsigned long pos) * so we just need to add the len to the current pointer for every * symbol we wish to skip. */ - for (i = 0; i < (pos & 0xFF); i++) - name = name + (*name) + 1; + for (i = 0; i < (pos & 0xFF); i++) { + len = *name; + + /* + * If MSB is 1, it is a "big" symbol, so we need to look into + * the next byte (and skip it, too). + */ + if ((len & 0x80) != 0) + len = ((len & 0x7F) | (name[1] << 7)) + 1; + + name = name + len + 1; + } return name - kallsyms_names; } -- cgit From b8a94bfb33952bb17fbc65f8903d242a721c533d Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Mon, 5 Apr 2021 05:03:50 +0200 Subject: kallsyms: increase maximum kernel symbol length to 512 Rust symbols can become quite long due to namespacing introduced by modules, types, traits, generics, etc. For instance, the following code: pub mod my_module { pub struct MyType; pub struct MyGenericType(T); pub trait MyTrait { fn my_method() -> u32; } impl MyTrait for MyGenericType { fn my_method() -> u32 { 42 } } } generates a symbol of length 96 when using the upcoming v0 mangling scheme: _RNvXNtCshGpAVYOtgW1_7example9my_moduleINtB2_13MyGenericTypeNtB2_6MyTypeENtB2_7MyTrait9my_method At the moment, Rust symbols may reach up to 300 in length. Setting 512 as the maximum seems like a reasonable choice to keep some headroom. Reviewed-by: Kees Cook Reviewed-by: Petr Mladek Reviewed-by: Greg Kroah-Hartman Co-developed-by: Alex Gaynor Signed-off-by: Alex Gaynor Co-developed-by: Wedson Almeida Filho Signed-off-by: Wedson Almeida Filho Co-developed-by: Gary Guo Signed-off-by: Gary Guo Co-developed-by: Boqun Feng Signed-off-by: Boqun Feng Signed-off-by: Miguel Ojeda --- kernel/livepatch/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index bc475e62279d..ec06ce59d728 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -213,7 +213,7 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab, * we use the smallest/strictest upper bound possible (56, based on * the current definition of MODULE_NAME_LEN) to prevent overflows. */ - BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 128); + BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 512); relas = (Elf_Rela *) relasec->sh_addr; /* For each rela in this klp relocation section */ @@ -227,7 +227,7 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab, /* Format: .klp.sym.sym_objname.sym_name,sympos */ cnt = sscanf(strtab + sym->st_name, - ".klp.sym.%55[^.].%127[^,],%lu", + ".klp.sym.%55[^.].%511[^,],%lu", sym_objname, sym_name, &sympos); if (cnt != 3) { pr_err("symbol %s has an incorrectly formatted name\n", -- cgit From 2f7ab1267dc9b2d1f29695aff3211c87483480f3 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sat, 3 Jul 2021 16:42:57 +0200 Subject: Kbuild: add Rust support MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Having most of the new files in place, we now enable Rust support in the build system, including `Kconfig` entries related to Rust, the Rust configuration printer and a few other bits. Reviewed-by: Kees Cook Reviewed-by: Nick Desaulniers Tested-by: Nick Desaulniers Reviewed-by: Greg Kroah-Hartman Co-developed-by: Alex Gaynor Signed-off-by: Alex Gaynor Co-developed-by: Finn Behrens Signed-off-by: Finn Behrens Co-developed-by: Adam Bratschi-Kaye Signed-off-by: Adam Bratschi-Kaye Co-developed-by: Wedson Almeida Filho Signed-off-by: Wedson Almeida Filho Co-developed-by: Michael Ellerman Signed-off-by: Michael Ellerman Co-developed-by: Sven Van Asbroeck Signed-off-by: Sven Van Asbroeck Co-developed-by: Gary Guo Signed-off-by: Gary Guo Co-developed-by: Boris-Chengbiao Zhou Signed-off-by: Boris-Chengbiao Zhou Co-developed-by: Boqun Feng Signed-off-by: Boqun Feng Co-developed-by: Douglas Su Signed-off-by: Douglas Su Co-developed-by: Dariusz Sosnowski Signed-off-by: Dariusz Sosnowski Co-developed-by: Antonio Terceiro Signed-off-by: Antonio Terceiro Co-developed-by: Daniel Xu Signed-off-by: Daniel Xu Co-developed-by: Björn Roy Baron Signed-off-by: Björn Roy Baron Co-developed-by: Martin Rodriguez Reboredo Signed-off-by: Martin Rodriguez Reboredo Signed-off-by: Miguel Ojeda --- kernel/configs/rust.config | 1 + 1 file changed, 1 insertion(+) create mode 100644 kernel/configs/rust.config (limited to 'kernel') diff --git a/kernel/configs/rust.config b/kernel/configs/rust.config new file mode 100644 index 000000000000..38a7c5362c9c --- /dev/null +++ b/kernel/configs/rust.config @@ -0,0 +1 @@ +CONFIG_RUST=y -- cgit