6.6-stable review patch. If anyone has any objections, please let me know.
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From: Leon Hwang leon.hwang@linux.dev
[ Upstream commit 4d99e509c161f8610de125202c648fa4acd00541 ]
This patch addresses the bpftool issue "Wrong callq address displayed"[0].
The issue stemmed from an incorrect program counter (PC) value used during disassembly with LLVM or libbfd.
For LLVM: The PC argument must represent the actual address in the kernel to compute the correct relative address.
For libbfd: The relative address can be adjusted by adding func_ksym within the custom info->print_address_func to yield the correct address.
Links: [0] https://github.com/libbpf/bpftool/issues/109
Changes: v2 -> v3: * Address comment from Quentin: * Remove the typedef.
v1 -> v2: * Fix the broken libbfd disassembler.
Fixes: e1947c750ffe ("bpftool: Refactor disassembler for JIT-ed programs") Signed-off-by: Leon Hwang leon.hwang@linux.dev Signed-off-by: Andrii Nakryiko andrii@kernel.org Tested-by: Quentin Monnet qmo@kernel.org Reviewed-by: Quentin Monnet qmo@kernel.org Acked-by: Yonghong Song yonghong.song@linux.dev Link: https://lore.kernel.org/bpf/20241031152844.68817-1-leon.hwang@linux.dev Signed-off-by: Sasha Levin sashal@kernel.org --- tools/bpf/bpftool/jit_disasm.c | 40 ++++++++++++++++++++++++---------- 1 file changed, 29 insertions(+), 11 deletions(-)
diff --git a/tools/bpf/bpftool/jit_disasm.c b/tools/bpf/bpftool/jit_disasm.c index 7b8d9ec89ebd3..c032d2c6ab6d5 100644 --- a/tools/bpf/bpftool/jit_disasm.c +++ b/tools/bpf/bpftool/jit_disasm.c @@ -80,7 +80,8 @@ symbol_lookup_callback(__maybe_unused void *disasm_info, static int init_context(disasm_ctx_t *ctx, const char *arch, __maybe_unused const char *disassembler_options, - __maybe_unused unsigned char *image, __maybe_unused ssize_t len) + __maybe_unused unsigned char *image, __maybe_unused ssize_t len, + __maybe_unused __u64 func_ksym) { char *triple;
@@ -109,12 +110,13 @@ static void destroy_context(disasm_ctx_t *ctx) }
static int -disassemble_insn(disasm_ctx_t *ctx, unsigned char *image, ssize_t len, int pc) +disassemble_insn(disasm_ctx_t *ctx, unsigned char *image, ssize_t len, int pc, + __u64 func_ksym) { char buf[256]; int count;
- count = LLVMDisasmInstruction(*ctx, image + pc, len - pc, pc, + count = LLVMDisasmInstruction(*ctx, image + pc, len - pc, func_ksym + pc, buf, sizeof(buf)); if (json_output) printf_json(buf); @@ -136,8 +138,21 @@ int disasm_init(void) #ifdef HAVE_LIBBFD_SUPPORT #define DISASM_SPACER "\t"
+struct disasm_info { + struct disassemble_info info; + __u64 func_ksym; +}; + +static void disasm_print_addr(bfd_vma addr, struct disassemble_info *info) +{ + struct disasm_info *dinfo = container_of(info, struct disasm_info, info); + + addr += dinfo->func_ksym; + generic_print_address(addr, info); +} + typedef struct { - struct disassemble_info *info; + struct disasm_info *info; disassembler_ftype disassemble; bfd *bfdf; } disasm_ctx_t; @@ -215,7 +230,7 @@ static int fprintf_json_styled(void *out,
static int init_context(disasm_ctx_t *ctx, const char *arch, const char *disassembler_options, - unsigned char *image, ssize_t len) + unsigned char *image, ssize_t len, __u64 func_ksym) { struct disassemble_info *info; char tpath[PATH_MAX]; @@ -238,12 +253,13 @@ static int init_context(disasm_ctx_t *ctx, const char *arch, } bfdf = ctx->bfdf;
- ctx->info = malloc(sizeof(struct disassemble_info)); + ctx->info = malloc(sizeof(struct disasm_info)); if (!ctx->info) { p_err("mem alloc failed"); goto err_close; } - info = ctx->info; + ctx->info->func_ksym = func_ksym; + info = &ctx->info->info;
if (json_output) init_disassemble_info_compat(info, stdout, @@ -272,6 +288,7 @@ static int init_context(disasm_ctx_t *ctx, const char *arch, info->disassembler_options = disassembler_options; info->buffer = image; info->buffer_length = len; + info->print_address_func = disasm_print_addr;
disassemble_init_for_target(info);
@@ -304,9 +321,10 @@ static void destroy_context(disasm_ctx_t *ctx)
static int disassemble_insn(disasm_ctx_t *ctx, __maybe_unused unsigned char *image, - __maybe_unused ssize_t len, int pc) + __maybe_unused ssize_t len, int pc, + __maybe_unused __u64 func_ksym) { - return ctx->disassemble(pc, ctx->info); + return ctx->disassemble(pc, &ctx->info->info); }
int disasm_init(void) @@ -331,7 +349,7 @@ int disasm_print_insn(unsigned char *image, ssize_t len, int opcodes, if (!len) return -1;
- if (init_context(&ctx, arch, disassembler_options, image, len)) + if (init_context(&ctx, arch, disassembler_options, image, len, func_ksym)) return -1;
if (json_output) @@ -360,7 +378,7 @@ int disasm_print_insn(unsigned char *image, ssize_t len, int opcodes, printf("%4x:" DISASM_SPACER, pc); }
- count = disassemble_insn(&ctx, image, len, pc); + count = disassemble_insn(&ctx, image, len, pc, func_ksym);
if (json_output) { /* Operand array, was started in fprintf_json. Before