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aarch64: tune down size of unw_context_t and unw_cursor_t (#71)

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aarch64 defines a huge __reserved field in sigcontext.  Cut it down
to only the used FP fields.

unw_cursor_t can also be cut down a bit, while still maintaining some reserved space.
This commit is contained in:
Dave Watson 2018-04-10 10:55:45 -07:00 committed by GitHub
parent b5cbcaee13
commit 729772149f
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GPG key ID: 4AEE18F83AFDEB23
3 changed files with 33 additions and 9 deletions
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32
include/libunwind-aarch64.h
View file

@ -44,9 +44,13 @@ extern "C" {
leaving some slack for future expansion. Changing this value will
require recompiling all users of this library. Stack allocation is
relatively cheap and unwind-state copying is relatively rare, so we
want to err on making it rather too big than too small. */
want to err on making it rather too big than too small.
#define UNW_TDEP_CURSOR_LEN 512
Calculation is regs used (64 + 34) * 2 + 40 (bytes of rest of
cursor) + padding
*/
#define UNW_TDEP_CURSOR_LEN 250
typedef uint64_t unw_word_t;
typedef int64_t unw_sword_t;
@ -169,8 +173,28 @@ typedef struct unw_tdep_save_loc
unw_tdep_save_loc_t;
/* On AArch64, we can directly use ucontext_t as the unwind context. */
typedef ucontext_t unw_tdep_context_t;
/* On AArch64, we can directly use ucontext_t as the unwind context,
* however, the __reserved struct is quite large: tune it down to only
* the necessary used fields. */
struct unw_sigcontext
{
uint64_t fault_address;
uint64_t regs[31];
uint64_t sp;
uint64_t pc;
uint64_t pstate;
uint8_t __reserved[(34 * 8)] __attribute__((__aligned__(16)));
};
typedef struct
{
unsigned long uc_flags;
struct ucontext *uc_link;
stack_t uc_stack;
__sigset_t uc_sigmask;
struct unw_sigcontext uc_mcontext;
} unw_tdep_context_t;
#include "libunwind-common.h"
#include "libunwind-dynamic.h"

8
src/aarch64/Ginit.c
View file

@ -41,7 +41,7 @@ static struct unw_addr_space local_addr_space;
unw_addr_space_t unw_local_addr_space = &local_addr_space;
static inline void *
uc_addr (ucontext_t *uc, int reg)
uc_addr (unw_tdep_context_t *uc, int reg)
{
if (reg >= UNW_AARCH64_X0 && reg < UNW_AARCH64_V0)
return &uc->uc_mcontext.regs[reg];
@ -54,7 +54,7 @@ uc_addr (ucontext_t *uc, int reg)
# ifdef UNW_LOCAL_ONLY
HIDDEN void *
tdep_uc_addr (ucontext_t *uc, int reg)
tdep_uc_addr (unw_tdep_context_t *uc, int reg)
{
return uc_addr (uc, reg);
}
@ -104,7 +104,7 @@ access_reg (unw_addr_space_t as, unw_regnum_t reg, unw_word_t *val, int write,
void *arg)
{
unw_word_t *addr;
ucontext_t *uc = arg;
unw_tdep_context_t *uc = arg;
if (unw_is_fpreg (reg))
goto badreg;
@ -133,7 +133,7 @@ static int
access_fpreg (unw_addr_space_t as, unw_regnum_t reg, unw_fpreg_t *val,
int write, void *arg)
{
ucontext_t *uc = arg;
unw_tdep_context_t *uc = arg;
unw_fpreg_t *addr;
if (!unw_is_fpreg (reg))

2
src/aarch64/Ginit_local.c
View file

@ -59,7 +59,7 @@ unw_init_local (unw_cursor_t *cursor, unw_context_t *uc)
}
int
unw_init_local2 (unw_cursor_t *cursor, ucontext_t *uc, int flag)
unw_init_local2 (unw_cursor_t *cursor, unw_tdep_context_t *uc, int flag)
{
if (!flag)
{