Date: Wed, 23 Dec 2015 17:54:19 +0000 (UTC) From: Andrew Turner <andrew@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r292663 - head/sys/cddl/dev/fbt/arm Message-ID: <201512231754.tBNHsJ6f018422@repo.freebsd.org>
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Author: andrew Date: Wed Dec 23 17:54:19 2015 New Revision: 292663 URL: https://svnweb.freebsd.org/changeset/base/292663 Log: Be stricter on which functions we can probe with FBT. We now only check the first instruction to see if it's either a pushm with lr, or a sub with sp. The former is the common case, with the latter used with va_args. This removes 12 probes. These are all hand-written assembly, with a few C functions with no stack usage. Submitted by: Howard Su <howard0su@gmail.com> Differential Revision: https://reviews.freebsd.org/D4419 Modified: head/sys/cddl/dev/fbt/arm/fbt_isa.c Modified: head/sys/cddl/dev/fbt/arm/fbt_isa.c ============================================================================== --- head/sys/cddl/dev/fbt/arm/fbt_isa.c Wed Dec 23 17:43:55 2015 (r292662) +++ head/sys/cddl/dev/fbt/arm/fbt_isa.c Wed Dec 23 17:54:19 2015 (r292663) @@ -35,6 +35,7 @@ #include <sys/param.h> #include <sys/dtrace.h> +#include <machine/stack.h> #include <machine/trap.h> #include "fbt.h" @@ -42,6 +43,7 @@ #define FBT_PUSHM 0xe92d0000 #define FBT_POPM 0xe8bd0000 #define FBT_JUMP 0xea000000 +#define FBT_SUBSP 0xe24dd000 #define FBT_ENTRY "entry" #define FBT_RETURN "return" @@ -111,12 +113,18 @@ fbt_provide_module_function(linker_file_ instr = (uint32_t *)symval->value; limit = (uint32_t *)(symval->value + symval->size); - for (; instr < limit; instr++) - if ((*instr & 0xffff0000) == FBT_PUSHM && - (*instr & 0x4000) != 0) - break; + /* + * va_arg functions has first instruction of + * sub sp, sp, #? + */ + if ((*instr & 0xfffff000) == FBT_SUBSP) + instr++; - if (instr >= limit) + /* + * check if insn is a pushm with LR + */ + if ((*instr & 0xffff0000) != FBT_PUSHM || + (*instr & (1 << LR)) == 0) return (0); fbt = malloc(sizeof (fbt_probe_t), M_FBT, M_WAITOK | M_ZERO);
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