From: He Kuang <heku...@huawei.com> arch_get_reg_info() is a helper function which converts register name like "%rax" to offset of a register in 'struct pt_regs', which is required by BPF prologue generator.
This patch replaces original string table by a 'struct reg_info' table, which records offset of registers according to its name. For x86, since there are two sub-archs (x86_32 and x86_64) but we can only get pt_regs for the arch we are currently on, this patch fills offset with '-1' for another sub-arch. This introduces a limitation to perf prologue that, we are unable to generate prologue on a x86_32 compiled perf for BPF programs targeted on x86_64 kernel. This limitation is acceptable, because this is a very rare usecase. Signed-off-by: Wang Nan <wangn...@huawei.com> Signed-off-by: He Kuang <heku...@huawei.com> Cc: Alexei Starovoitov <a...@plumgrid.com> Cc: Brendan Gregg <brendan.d.gr...@gmail.com> Cc: Daniel Borkmann <dan...@iogearbox.net> Cc: David Ahern <dsah...@gmail.com> Cc: He Kuang <heku...@huawei.com> Cc: Jiri Olsa <jo...@kernel.org> Cc: Kaixu Xia <xiaka...@huawei.com> Cc: Masami Hiramatsu <masami.hiramatsu...@hitachi.com> Cc: Namhyung Kim <namhy...@kernel.org> Cc: Paul Mackerras <pau...@samba.org> Cc: Peter Zijlstra <a.p.zijls...@chello.nl> Cc: Zefan Li <lize...@huawei.com> Cc: pi3or...@163.com Cc: Arnaldo Carvalho de Melo <a...@redhat.com> Link: http://lkml.kernel.org/n/1436445342-1402-34-git-send-email-wangn...@huawei.com --- tools/perf/arch/x86/Makefile | 1 + tools/perf/arch/x86/util/Build | 2 + tools/perf/arch/x86/util/dwarf-regs.c | 104 ++++++++++++++++++++++++---------- 3 files changed, 78 insertions(+), 29 deletions(-) diff --git a/tools/perf/arch/x86/Makefile b/tools/perf/arch/x86/Makefile index 21322e0..a84a6f6f 100644 --- a/tools/perf/arch/x86/Makefile +++ b/tools/perf/arch/x86/Makefile @@ -2,3 +2,4 @@ ifndef NO_DWARF PERF_HAVE_DWARF_REGS := 1 endif HAVE_KVM_STAT_SUPPORT := 1 +PERF_HAVE_ARCH_GET_REG_INFO := 1 diff --git a/tools/perf/arch/x86/util/Build b/tools/perf/arch/x86/util/Build index 2c55e1b..09429f6 100644 --- a/tools/perf/arch/x86/util/Build +++ b/tools/perf/arch/x86/util/Build @@ -3,6 +3,8 @@ libperf-y += tsc.o libperf-y += pmu.o libperf-y += kvm-stat.o +# BPF_PROLOGUE also need dwarf-regs.o. However, if CONFIG_BPF_PROLOGUE +# is true, CONFIG_DWARF must true. libperf-$(CONFIG_DWARF) += dwarf-regs.o libperf-$(CONFIG_LIBUNWIND) += unwind-libunwind.o diff --git a/tools/perf/arch/x86/util/dwarf-regs.c b/tools/perf/arch/x86/util/dwarf-regs.c index be22dd4..9928caf 100644 --- a/tools/perf/arch/x86/util/dwarf-regs.c +++ b/tools/perf/arch/x86/util/dwarf-regs.c @@ -22,44 +22,67 @@ #include <stddef.h> #include <dwarf-regs.h> +#include <string.h> +#include <linux/ptrace.h> +#include <linux/kernel.h> /* for offsetof */ +#include <util/bpf-loader.h> + +struct reg_info { + const char *name; /* Reg string in debuginfo */ + int offset; /* Reg offset in struct pt_regs */ +}; /* * Generic dwarf analysis helpers */ - +/* + * x86_64 compiling can't access pt_regs for x86_32, so fill offset + * with -1. + */ +#ifdef __x86_64__ +# define REG_INFO(n, f) { .name = n, .offset = -1, } +#else +# define REG_INFO(n, f) { .name = n, .offset = offsetof(struct pt_regs, f), } +#endif #define X86_32_MAX_REGS 8 -const char *x86_32_regs_table[X86_32_MAX_REGS] = { - "%ax", - "%cx", - "%dx", - "%bx", - "$stack", /* Stack address instead of %sp */ - "%bp", - "%si", - "%di", + +struct reg_info x86_32_regs_table[X86_32_MAX_REGS] = { + REG_INFO("%ax", eax), + REG_INFO("%cx", ecx), + REG_INFO("%dx", edx), + REG_INFO("%bx", ebx), + REG_INFO("$stack", esp), /* Stack address instead of %sp */ + REG_INFO("%bp", ebp), + REG_INFO("%si", esi), + REG_INFO("%di", edi), }; +#undef REG_INFO +#ifdef __x86_64__ +# define REG_INFO(n, f) { .name = n, .offset = offsetof(struct pt_regs, f), } +#else +# define REG_INFO(n, f) { .name = n, .offset = -1, } +#endif #define X86_64_MAX_REGS 16 -const char *x86_64_regs_table[X86_64_MAX_REGS] = { - "%ax", - "%dx", - "%cx", - "%bx", - "%si", - "%di", - "%bp", - "%sp", - "%r8", - "%r9", - "%r10", - "%r11", - "%r12", - "%r13", - "%r14", - "%r15", +struct reg_info x86_64_regs_table[X86_64_MAX_REGS] = { + REG_INFO("%ax", rax), + REG_INFO("%dx", rdx), + REG_INFO("%cx", rcx), + REG_INFO("%bx", rbx), + REG_INFO("%si", rsi), + REG_INFO("%di", rdi), + REG_INFO("%bp", rbp), + REG_INFO("%sp", rsp), + REG_INFO("%r8", r8), + REG_INFO("%r9", r9), + REG_INFO("%r10", r10), + REG_INFO("%r11", r11), + REG_INFO("%r12", r12), + REG_INFO("%r13", r13), + REG_INFO("%r14", r14), + REG_INFO("%r15", r15), }; -/* TODO: switching by dwarf address size */ #ifdef __x86_64__ #define ARCH_MAX_REGS X86_64_MAX_REGS #define arch_regs_table x86_64_regs_table @@ -71,5 +94,28 @@ const char *x86_64_regs_table[X86_64_MAX_REGS] = { /* Return architecture dependent register string (for kprobe-tracer) */ const char *get_arch_regstr(unsigned int n) { - return (n <= ARCH_MAX_REGS) ? arch_regs_table[n] : NULL; + return (n <= ARCH_MAX_REGS) ? arch_regs_table[n].name : NULL; } + +#ifdef HAVE_BPF_PROLOGUE +int arch_get_reg_info(const char *name, int *offset) +{ + int i; + struct reg_info *info; + + if (!name || !offset) + return -1; + + for (i = 0; i < ARCH_MAX_REGS; i++) { + info = &arch_regs_table[i]; + if (strcmp(info->name, name) == 0) { + if (info->offset < 0) + return -1; + *offset = info->offset; + return 0; + } + } + + return -1; +} +#endif -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
