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trace: conserve gd register

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An UEFI application may change the value of the register that gd lives in.
But some of our functions like get_ticks() access this register. So we
have to set the gd register to the U-Boot value when entering a trace
point and set it back to the application value when exiting the trace
point.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Heinrich Schuchardt 2019-06-02 13:05:08 +02:00 • committed by Simon Glass
parent 7ef8e9b09a
commit a2fa38da20
1 changed files with 49 additions and 0 deletions
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49
lib/trace.c
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@ -56,6 +56,49 @@ static inline uintptr_t __attribute__((no_instrument_function))
return offset / FUNC_SITE_SIZE;
}
#ifdef CONFIG_EFI_LOADER
/**
* trace_gd - the value of the gd register
*/
static volatile void *trace_gd;
/**
* trace_save_gd() - save the value of the gd register
*/
static void __attribute__((no_instrument_function)) trace_save_gd(void)
{
trace_gd = gd;
}
/**
* trace_swap_gd() - swap between U-Boot and application gd register value
*
* An UEFI application may change the value of the register that gd lives in.
* But some of our functions like get_ticks() access this register. So we
* have to set the gd register to the U-Boot value when entering a trace
* point and set it back to the application value when exiting the trace point.
*/
static void __attribute__((no_instrument_function)) trace_swap_gd(void)
{
volatile void *temp_gd = trace_gd;
trace_gd = gd;
gd = temp_gd;
}
#else
static void __attribute__((no_instrument_function)) trace_save_gd(void)
{
}
static void __attribute__((no_instrument_function)) trace_swap_gd(void)
{
}
#endif
static void __attribute__((no_instrument_function)) add_ftrace(void *func_ptr,
void *caller, ulong flags)
{
@ -100,6 +143,7 @@ void __attribute__((no_instrument_function)) __cyg_profile_func_enter(
if (trace_enabled) {
int func;
trace_swap_gd();
add_ftrace(func_ptr, caller, FUNCF_ENTRY);
func = func_ptr_to_num(func_ptr);
if (func < hdr->func_count) {
@ -111,6 +155,7 @@ void __attribute__((no_instrument_function)) __cyg_profile_func_enter(
hdr->depth++;
if (hdr->depth > hdr->depth_limit)
hdr->max_depth = hdr->depth;
trace_swap_gd();
}
}
@ -126,8 +171,10 @@ void __attribute__((no_instrument_function)) __cyg_profile_func_exit(
void *func_ptr, void *caller)
{
if (trace_enabled) {
trace_swap_gd();
add_ftrace(func_ptr, caller, FUNCF_EXIT);
hdr->depth--;
trace_swap_gd();
}
}
@ -284,6 +331,8 @@ int __attribute__((no_instrument_function)) trace_init(void *buff,
size_t needed;
int was_disabled = !trace_enabled;
trace_save_gd();
if (!was_disabled) {
#ifdef CONFIG_TRACE_EARLY
char *end;