[PATCH 2/2] arm: smp: Fix SMP for xip kernels

From: Harith George
Date: Wed Jul 31 2024 - 07:39:42 EST


From: Harith George <harith.g@xxxxxxxxxxxx>

Fix the physical address calculation of the following to get smp working
on xip kernels.
- secondary_data needed for secondary cpu bootup.
- secondary_startup address passed through psci.
- identity mapped code region needed for enabling mmu for secondary cpus.

Signed-off-by: Harith George <harith.g@xxxxxxxxxxxx>
---
arch/arm/kernel/head.S | 4 ++++
arch/arm/kernel/psci_smp.c | 7 +++++++
arch/arm/mm/idmap.c | 7 +++++++
3 files changed, 18 insertions(+)

diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 28873cda464f..f22c50d4bd41 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -411,7 +411,11 @@ ENTRY(secondary_startup)
/*
* Use the page tables supplied from __cpu_up.
*/
+#ifdef CONFIG_XIP_KERNEL
+ ldr r3, =(secondary_data + PLAT_PHYS_OFFSET - PAGE_OFFSET)
+#else
adr_l r3, secondary_data
+#endif
mov_l r12, __secondary_switched
ldrd r4, r5, [r3, #0] @ get secondary_data.pgdir
ARM_BE8(eor r4, r4, r5) @ Swap r5 and r4 in BE:
diff --git a/arch/arm/kernel/psci_smp.c b/arch/arm/kernel/psci_smp.c
index d4392e177484..3bb0c4dcfc5c 100644
--- a/arch/arm/kernel/psci_smp.c
+++ b/arch/arm/kernel/psci_smp.c
@@ -45,8 +45,15 @@ extern void secondary_startup(void);
static int psci_boot_secondary(unsigned int cpu, struct task_struct *idle)
{
if (psci_ops.cpu_on)
+#ifdef CONFIG_XIP_KERNEL
+ return psci_ops.cpu_on(cpu_logical_map(cpu),
+ ((phys_addr_t)(&secondary_startup)
+ - XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR)
+ + CONFIG_XIP_PHYS_ADDR));
+#else
return psci_ops.cpu_on(cpu_logical_map(cpu),
virt_to_idmap(&secondary_startup));
+#endif
return -ENODEV;
}

diff --git a/arch/arm/mm/idmap.c b/arch/arm/mm/idmap.c
index 448e57c6f653..4a833e89782a 100644
--- a/arch/arm/mm/idmap.c
+++ b/arch/arm/mm/idmap.c
@@ -84,8 +84,15 @@ static void identity_mapping_add(pgd_t *pgd, const char *text_start,
unsigned long addr, end;
unsigned long next;

+#ifdef CONFIG_XIP_KERNEL
+ addr = (phys_addr_t)(text_start) - XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR)
+ + CONFIG_XIP_PHYS_ADDR;
+ end = (phys_addr_t)(text_end) - XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR)
+ + CONFIG_XIP_PHYS_ADDR;
+#else
addr = virt_to_idmap(text_start);
end = virt_to_idmap(text_end);
+#endif
pr_info("Setting up static identity map for 0x%lx - 0x%lx\n", addr, end);

prot |= PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
--
2.34.1