From 2ba605f32ac3c673ef0f0bee810a2696f1887488 Mon Sep 17 00:00:00 2001 From: Igor Ostapenko Date: Tue, 3 Oct 2023 19:48:00 +0300 Subject: [PATCH] dtrace: fix fbt regression for aarch64 fbt computes incorrect instruction position for AArch64 kernel module symbol. The issue is with the for loop, it does an extra increment of instr pointer after the required instruction is found. Hence, a wrong instruction is targeted for patching. Signed-off-by: Igor Ostapenko Fixes: 980746e5cb26 ("fbt: simplify arm64 function-prologue parsing") Reviewed by: markj Pull Request: https://github.com/freebsd/freebsd-src/pull/855 MFC after: 1 week (cherry picked from commit b4db386f9fa7be9668aa09d14b0bbd048a7a7e89) --- sys/cddl/dev/fbt/aarch64/fbt_isa.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) diff --git a/sys/cddl/dev/fbt/aarch64/fbt_isa.c b/sys/cddl/dev/fbt/aarch64/fbt_isa.c index 4094ea43a9f..44690b97f77 100644 --- a/sys/cddl/dev/fbt/aarch64/fbt_isa.c +++ b/sys/cddl/dev/fbt/aarch64/fbt_isa.c @@ -90,7 +90,6 @@ fbt_provide_module_function(linker_file_t lf, int symindx, uint32_t *instr, *limit; const char *name; char *modname; - bool found; int offs; modname = opaque; @@ -119,16 +118,16 @@ fbt_provide_module_function(linker_file_t lf, int symindx, if ((*instr & BTI_MASK) == BTI_INSTR) instr++; - /* Look for stp (pre-indexed) operation */ - found = false; /* * If the first instruction is a nop it's a specially marked * asm function. We only support a nop first as it's not a normal * part of the function prologue. */ if (*instr == NOP_INSTR) - found = true; - for (; !found && instr < limit; instr++) { + goto found; + + /* Look for stp (pre-indexed) or sub operation */ + for (; instr < limit; instr++) { /* * Functions start with "stp xt1, xt2, [xn, ]!" or * "sub sp, sp, ". @@ -142,14 +141,14 @@ fbt_provide_module_function(linker_file_t lf, int symindx, * past the function prologue. */ if (((*instr >> ADDR_SHIFT) & ADDR_MASK) == 31) - found = true; + break; } else if ((*instr & SUB_MASK) == SUB_INSTR && ((*instr >> SUB_RD_SHIFT) & SUB_R_MASK) == 31 && ((*instr >> SUB_RN_SHIFT) & SUB_R_MASK) == 31) - found = true; + break; } - - if (!found) +found: + if (instr >= limit) return (0); fbt = malloc(sizeof (fbt_probe_t), M_FBT, M_WAITOK | M_ZERO);