From 92e74fb6e6196d642505ae2b74a8e327202afef9 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Mon, 5 Jun 2023 21:04:00 +0900 Subject: scripts/kallsyms: constify long_options getopt_long() does not modify this. Signed-off-by: Masahiro Yamada Reviewed-by: Nicolas Schier --- scripts/kallsyms.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'scripts/kallsyms.c') diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c index 0d2db41177b2..8e97ac7b38a6 100644 --- a/scripts/kallsyms.c +++ b/scripts/kallsyms.c @@ -806,7 +806,7 @@ static void record_relative_base(void) int main(int argc, char **argv) { while (1) { - static struct option long_options[] = { + static const struct option long_options[] = { {"all-symbols", no_argument, &all_symbols, 1}, {"absolute-percpu", no_argument, &absolute_percpu, 1}, {"base-relative", no_argument, &base_relative, 1}, -- cgit v1.2.3 From 1c975da56a6f89a3e610cc86d92f65de3da7bd61 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Mon, 5 Jun 2023 21:26:04 +0900 Subject: scripts/kallsyms: remove KSYM_NAME_LEN_BUFFER You do not need to decide the buffer size statically. Use getline() to grow the line buffer as needed. Signed-off-by: Masahiro Yamada Reviewed-by: Nicolas Schier --- scripts/kallsyms.c | 61 ++++++++++++++++++++++++++++-------------------------- 1 file changed, 32 insertions(+), 29 deletions(-) (limited to 'scripts/kallsyms.c') diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c index 8e97ac7b38a6..d387c9381650 100644 --- a/scripts/kallsyms.c +++ b/scripts/kallsyms.c @@ -19,6 +19,7 @@ * */ +#include #include #include #include @@ -29,24 +30,8 @@ #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0])) -#define _stringify_1(x) #x -#define _stringify(x) _stringify_1(x) - #define KSYM_NAME_LEN 512 -/* - * A substantially bigger size than the current maximum. - * - * It cannot be defined as an expression because it gets stringified - * for the fscanf() format string. Therefore, a _Static_assert() is - * used instead to maintain the relationship with KSYM_NAME_LEN. - */ -#define KSYM_NAME_LEN_BUFFER 2048 -_Static_assert( - KSYM_NAME_LEN_BUFFER == KSYM_NAME_LEN * 4, - "Please keep KSYM_NAME_LEN_BUFFER in sync with KSYM_NAME_LEN" -); - struct sym_entry { unsigned long long addr; unsigned int len; @@ -136,24 +121,40 @@ static void check_symbol_range(const char *sym, unsigned long long addr, } } -static struct sym_entry *read_symbol(FILE *in) +static struct sym_entry *read_symbol(FILE *in, char **buf, size_t *buf_len) { - char name[KSYM_NAME_LEN_BUFFER+1], type; + char *name, type, *p; unsigned long long addr; - unsigned int len; + size_t len; + ssize_t readlen; struct sym_entry *sym; - int rc; - rc = fscanf(in, "%llx %c %" _stringify(KSYM_NAME_LEN_BUFFER) "s\n", &addr, &type, name); - if (rc != 3) { - if (rc != EOF && fgets(name, ARRAY_SIZE(name), in) == NULL) - fprintf(stderr, "Read error or end of file.\n"); + readlen = getline(buf, buf_len, in); + if (readlen < 0) { + if (errno) { + perror("read_symbol"); + exit(EXIT_FAILURE); + } return NULL; } - if (strlen(name) >= KSYM_NAME_LEN) { + + if ((*buf)[readlen - 1] == '\n') + (*buf)[readlen - 1] = 0; + + addr = strtoull(*buf, &p, 16); + + if (*buf == p || *p++ != ' ' || !isascii((type = *p++)) || *p++ != ' ') { + fprintf(stderr, "line format error\n"); + exit(EXIT_FAILURE); + } + + name = p; + len = strlen(name); + + if (len >= KSYM_NAME_LEN) { fprintf(stderr, "Symbol %s too long for kallsyms (%zu >= %d).\n" "Please increase KSYM_NAME_LEN both in kernel and kallsyms.c\n", - name, strlen(name), KSYM_NAME_LEN); + name, len, KSYM_NAME_LEN); return NULL; } @@ -169,8 +170,7 @@ static struct sym_entry *read_symbol(FILE *in) /* include the type field in the symbol name, so that it gets * compressed together */ - - len = strlen(name) + 1; + len++; sym = malloc(sizeof(*sym) + len + 1); if (!sym) { @@ -257,6 +257,8 @@ static void read_map(const char *in) { FILE *fp; struct sym_entry *sym; + char *buf = NULL; + size_t buflen = 0; fp = fopen(in, "r"); if (!fp) { @@ -265,7 +267,7 @@ static void read_map(const char *in) } while (!feof(fp)) { - sym = read_symbol(fp); + sym = read_symbol(fp, &buf, &buflen); if (!sym) continue; @@ -284,6 +286,7 @@ static void read_map(const char *in) table[table_cnt++] = sym; } + free(buf); fclose(fp); } -- cgit v1.2.3 From 8cc32a9bbf2934d90762d9de0187adcb5ad46a11 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Wed, 28 Jun 2023 11:19:26 -0700 Subject: kallsyms: strip LTO-only suffixes from promoted global functions Commit 6eb4bd92c1ce ("kallsyms: strip LTO suffixes from static functions") stripped all function/variable suffixes started with '.' regardless of whether those suffixes are generated at LTO mode or not. In fact, as far as I know, in LTO mode, when a static function/variable is promoted to the global scope, '.llvm.<...>' suffix is added. The existing mechanism breaks live patch for a LTO kernel even if no .llvm.<...> symbols are involved. For example, for the following kernel symbols: $ grep bpf_verifier_vlog /proc/kallsyms ffffffff81549f60 t bpf_verifier_vlog ffffffff8268b430 d bpf_verifier_vlog._entry ffffffff8282a958 d bpf_verifier_vlog._entry_ptr ffffffff82e12a1f d bpf_verifier_vlog.__already_done 'bpf_verifier_vlog' is a static function. '_entry', '_entry_ptr' and '__already_done' are static variables used inside 'bpf_verifier_vlog', so llvm promotes them to file-level static with prefix 'bpf_verifier_vlog.'. Note that the func-level to file-level static function promotion also happens without LTO. Given a symbol name 'bpf_verifier_vlog', with LTO kernel, current mechanism will return 4 symbols to live patch subsystem which current live patching subsystem cannot handle it. With non-LTO kernel, only one symbol is returned. In [1], we have a lengthy discussion, the suggestion is to separate two cases: (1). new symbols with suffix which are generated regardless of whether LTO is enabled or not, and (2). new symbols with suffix generated only when LTO is enabled. The cleanup_symbol_name() should only remove suffixes for case (2). Case (1) should not be changed so it can work uniformly with or without LTO. This patch removed LTO-only suffix '.llvm.<...>' so live patching and tracing should work the same way for non-LTO kernel. The cleanup_symbol_name() in scripts/kallsyms.c is also changed to have the same filtering pattern so both kernel and kallsyms tool have the same expectation on the order of symbols. [1] https://lore.kernel.org/live-patching/20230615170048.2382735-1-song@kernel.org/T/#u Fixes: 6eb4bd92c1ce ("kallsyms: strip LTO suffixes from static functions") Reported-by: Song Liu Signed-off-by: Yonghong Song Reviewed-by: Zhen Lei Reviewed-by: Nick Desaulniers Acked-by: Song Liu Link: https://lore.kernel.org/r/20230628181926.4102448-1-yhs@fb.com Signed-off-by: Kees Cook --- kernel/kallsyms.c | 5 ++--- scripts/kallsyms.c | 6 +++--- 2 files changed, 5 insertions(+), 6 deletions(-) (limited to 'scripts/kallsyms.c') diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index 7982cc9d497c..016d997131d4 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -174,11 +174,10 @@ static bool cleanup_symbol_name(char *s) * LLVM appends various suffixes for local functions and variables that * must be promoted to global scope as part of LTO. This can break * hooking of static functions with kprobes. '.' is not a valid - * character in an identifier in C. Suffixes observed: + * character in an identifier in C. Suffixes only in LLVM LTO observed: * - foo.llvm.[0-9a-f]+ - * - foo.[0-9a-f]+ */ - res = strchr(s, '.'); + res = strstr(s, ".llvm."); if (res) { *res = '\0'; return true; diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c index d387c9381650..16c87938b316 100644 --- a/scripts/kallsyms.c +++ b/scripts/kallsyms.c @@ -349,10 +349,10 @@ static void cleanup_symbol_name(char *s) * ASCII[_] = 5f * ASCII[a-z] = 61,7a * - * As above, replacing '.' with '\0' does not affect the main sorting, - * but it helps us with subsorting. + * As above, replacing the first '.' in ".llvm." with '\0' does not + * affect the main sorting, but it helps us with subsorting. */ - p = strchr(s, '.'); + p = strstr(s, ".llvm."); if (p) *p = '\0'; } -- cgit v1.2.3