From 3c814b2e2b8e053da352f4746a4914fb43af09d7 Mon Sep 17 00:00:00 2001 From: Julius Werner Date: Fri, 19 Aug 2016 16:20:40 -0700 Subject: cbmem: Always maintain backing store struct in a global on non-x86 The current CBMEM code contains an optimization that maintains the structure with information about the CBMEM backing store in a global variable, so that we don't have to recover it from cbmem_top() again every single time we access CBMEM. However, due to the problems with using globals in x86 romstage, this optimization has only been enabled in ramstage. However, all non-x86 platforms are SRAM-based (at least for now) and can use globals perfectly fine in earlier stages. Therefore, this patch extends the optimization on those platforms to all stages. This also allows us to remove the requirement that cbmem_top() needs to return NULL before its backing store has been initialized from those boards, since the CBMEM code can now keep track of whether it has been initialized by itself. Change-Id: Ia6c1db00ae01dee485d5e96e4315cb399dc63696 Signed-off-by: Julius Werner Reviewed-on: https://review.coreboot.org/16273 Tested-by: build bot (Jenkins) Reviewed-by: Aaron Durbin --- src/lib/imd_cbmem.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) (limited to 'src/lib') diff --git a/src/lib/imd_cbmem.c b/src/lib/imd_cbmem.c index 3e3e2b0637..d72f0b034a 100644 --- a/src/lib/imd_cbmem.c +++ b/src/lib/imd_cbmem.c @@ -26,10 +26,23 @@ #include #endif +/* + * We need special handling on x86 before ramstage because we cannot use global + * variables (we're executing in-place from flash so we don't have a writable + * data segment, and we cannot use CAR_GLOBAL here since that mechanism itself + * is dependent on CBMEM). Therefore, we have to always try to partially recover + * CBMEM from cbmem_top() whenever we try to access it. In other environments + * we're not so constrained and just keep the backing imd struct in a global. + * This also means that we can easily tell whether CBMEM has explicitly been + * initialized or recovered yet on those platforms, and don't need to put the + * burden on board or chipset code to tell us by returning NULL from cbmem_top() + * before that point. + */ +#define CAN_USE_GLOBALS (!IS_ENABLED(CONFIG_ARCH_X86) || ENV_RAMSTAGE) + static inline struct imd *cbmem_get_imd(void) { - /* Only supply a backing store for imd in ramstage. */ - if (ENV_RAMSTAGE) { + if (CAN_USE_GLOBALS) { static struct imd imd_cbmem; return &imd_cbmem; } @@ -77,11 +90,10 @@ static struct imd *imd_init_backing_with_recover(struct imd *backing) struct imd *imd; imd = imd_init_backing(backing); - if (!ENV_RAMSTAGE) { + if (!CAN_USE_GLOBALS) { + /* Always partially recover if we can't keep track of whether + * we have already initialized CBMEM in this stage. */ imd_handle_init(imd, cbmem_top()); - - /* Need to partially recover all the time outside of ramstage - * because there's object storage outside of the stack. */ imd_handle_init_partial_recovery(imd); } -- cgit v1.2.3