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Be stricter on which functions we can probe with FBT. We now only check the

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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
This commit is contained in:
Andrew Turner 2015-12-23 17:54:19 +00:00
parent b59f7a7ad8
commit 06ef48781d
1 changed files with 13 additions and 5 deletions
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18
sys/cddl/dev/fbt/arm/fbt_isa.c
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@ -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_t lf, int symindx,
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);