u-boot/arch/arm/include/asm/global_data.h
Marek Behún 86c5e21013 ARM: make gd a function call for LTO and set via set_gd()
On ARM, the gd pointer is stored in registers r9 / x18. For this the
-ffixed-r9 / -ffixed-x18 flag is used when compiling, but using global
register variables causes errors when building with LTO, and these
errors are very difficult to overcome.

Richard Biener says [1]:
  Note that global register vars shouldn't be used with LTO and if they
  are restricted to just a few compilation units the recommended fix is
  to build those CUs without -flto.

We cannot do this for U-Boot since all CUs use -ffixed-reg flag.

It seems that with LTO we could in fact store the gd pointer differently
and gain performance or size benefit by allowing the compiler to use
r9 / x18. But this would need more work.

So for now, when building with LTO, go the clang way, and instead of
declaring gd a global register variable, we make it a function call via
macro.

[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68384

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Simon Glass <sjg@chromium.org>
2021-05-24 14:21:30 -04:00

134 lines
3 KiB
C

/* SPDX-License-Identifier: GPL-2.0+ */
/*
* (C) Copyright 2002-2010
* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
*/
#ifndef __ASM_GBL_DATA_H
#define __ASM_GBL_DATA_H
#ifndef __ASSEMBLY__
#include <asm/types.h>
#include <linux/types.h>
/* Architecture-specific global data */
struct arch_global_data {
#if defined(CONFIG_FSL_ESDHC) || defined(CONFIG_FSL_ESDHC_IMX)
u32 sdhc_clk;
#endif
#if defined(CONFIG_FSL_ESDHC)
u32 sdhc_per_clk;
#endif
#if defined(CONFIG_U_QE)
u32 qe_clk;
u32 brg_clk;
uint mp_alloc_base;
uint mp_alloc_top;
#endif /* CONFIG_U_QE */
#ifdef CONFIG_AT91FAMILY
/* "static data" needed by at91's clock.c */
unsigned long cpu_clk_rate_hz;
unsigned long main_clk_rate_hz;
unsigned long mck_rate_hz;
unsigned long plla_rate_hz;
unsigned long pllb_rate_hz;
unsigned long at91_pllb_usb_init;
#endif
/* "static data" needed by most of timer.c on ARM platforms */
unsigned long timer_rate_hz;
unsigned int tbu;
unsigned int tbl;
unsigned long lastinc;
unsigned long long timer_reset_value;
#if !(CONFIG_IS_ENABLED(SYS_ICACHE_OFF) && CONFIG_IS_ENABLED(SYS_DCACHE_OFF))
unsigned long tlb_addr;
unsigned long tlb_size;
#if defined(CONFIG_ARM64)
unsigned long tlb_fillptr;
unsigned long tlb_emerg;
#endif
#endif
#ifdef CONFIG_SYS_MEM_RESERVE_SECURE
#define MEM_RESERVE_SECURE_SECURED 0x1
#define MEM_RESERVE_SECURE_MAINTAINED 0x2
#define MEM_RESERVE_SECURE_ADDR_MASK (~0x3)
/*
* Secure memory addr
* This variable needs maintenance if the RAM base is not zero,
* or if RAM splits into non-consecutive banks. It also has a
* flag indicating the secure memory is marked as secure by MMU.
* Flags used: 0x1 secured
* 0x2 maintained
*/
phys_addr_t secure_ram;
unsigned long tlb_allocated;
#endif
#ifdef CONFIG_RESV_RAM
/*
* Reserved RAM for memory resident, eg. Management Complex (MC)
* driver which continues to run after U-Boot exits.
*/
phys_addr_t resv_ram;
#endif
#ifdef CONFIG_ARCH_OMAP2PLUS
u32 omap_boot_device;
u32 omap_boot_mode;
u8 omap_ch_flags;
#endif
#if defined(CONFIG_FSL_LSCH3) && defined(CONFIG_SYS_FSL_HAS_DP_DDR)
unsigned long mem2_clk;
#endif
#ifdef CONFIG_ARCH_IMX8
struct udevice *scu_dev;
#endif
};
#include <asm-generic/global_data.h>
#if defined(__clang__) || defined(CONFIG_LTO)
#define DECLARE_GLOBAL_DATA_PTR
#define gd get_gd()
static inline gd_t *get_gd(void)
{
gd_t *gd_ptr;
#ifdef CONFIG_ARM64
__asm__ volatile("mov %0, x18\n" : "=r" (gd_ptr));
#else
__asm__ volatile("mov %0, r9\n" : "=r" (gd_ptr));
#endif
return gd_ptr;
}
#else
#ifdef CONFIG_ARM64
#define DECLARE_GLOBAL_DATA_PTR register volatile gd_t *gd asm ("x18")
#else
#define DECLARE_GLOBAL_DATA_PTR register volatile gd_t *gd asm ("r9")
#endif
#endif
static inline void set_gd(volatile gd_t *gd_ptr)
{
#ifdef CONFIG_ARM64
__asm__ volatile("ldr x18, %0\n" : : "m"(gd_ptr));
#elif __ARM_ARCH >= 7
__asm__ volatile("ldr r9, %0\n" : : "m"(gd_ptr));
#else
__asm__ volatile("mov r9, %0\n" : : "r"(gd_ptr));
#endif
}
#endif /* __ASSEMBLY__ */
#endif /* __ASM_GBL_DATA_H */