[coreboot-gerrit] Change in coreboot[master]: cpu/x86/smm: Add a helper function returning top of save state

[Arthur Heymans (Code Review)]

Arthur Heymans has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/37008 )

Change subject: cpu/x86/smm: Add a helper function returning top of save state
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cpu/x86/smm: Add a helper function returning top of save state

Some entries like smm base and smm revision have a fixed location in
the save w.r.t. the save state top.

Change-Id: I82dadcb966ee686c1652c7a1298dcb9938ae888c
Signed-off-by: Arthur Heymans 
---
M src/cpu/x86/smm/smihandler.c
M src/cpu/x86/smm/smm_module_handler.c
M src/include/cpu/x86/smm.h
3 files changed, 21 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/08/37008/1

diff --git a/src/cpu/x86/smm/smihandler.c b/src/cpu/x86/smm/smihandler.c
index 20417d1..79a3936 100644
--- a/src/cpu/x86/smm/smihandler.c
+++ b/src/cpu/x86/smm/smihandler.c
@@ -132,6 +132,13 @@
    return (void *)base;
 }

+uint8_t *smm_get_save_state_top(int cpu)
+{
+	const uint32_t smm_base = 0xa0000;
+
+	return (uint8_t *)smm_base + SMM_ENTRY_OFFSET * 2 - (cpu * 0x400);
+}
+
 /**
  * @brief Interrupt handler for SMI#
  *
diff --git a/src/cpu/x86/smm/smm_module_handler.c b/src/cpu/x86/smm/smm_module_handler.c
index bd4d48c..80bff9f 100644
--- a/src/cpu/x86/smm/smm_module_handler.c
+++ b/src/cpu/x86/smm/smm_module_handler.c
@@ -114,6 +114,19 @@
    return base;
 }

+uint8_t *smm_get_save_state_top(int cpu)
+{
+	uint8_t *base;
+
+	/* This function assumes all save states start at top of default
+	 * SMRAM size space and are staggered down by save state size. */
+	base = (void *)smm_runtime->smbase;
+	base += SMM_DEFAULT_SIZE;
+	base -= cpu * smm_runtime->save_state_size;
+
+	return base;
+}
+
 asmlinkage void smm_handler_start(void *arg)
 {
    const struct smm_module_params *p;
diff --git a/src/include/cpu/x86/smm.h b/src/include/cpu/x86/smm.h
index cf107b1..0ade970 100644
--- a/src/include/cpu/x86/smm.h
+++ b/src/include/cpu/x86/smm.h
@@ -94,6 +94,7 @@
 /* Retrieve SMM save state for a given CPU. WARNING: This does not take into
  * account CPUs which are configured to not save their state to RAM. */
 void *smm_get_save_state(int cpu);
+uint8_t *smm_get_save_state_top(int cpu);

/* SMM Module Loading API */