Subject: [PATCH v3 09/13] powerpc: extend execmem_params for kprobes allocations

From: Mike Rapoport <[email-masked]>
Date: Mon, 18 Sep 2023 10:29:51 +0300

From: "Mike Rapoport (IBM)" <[email-masked]>

powerpc overrides kprobes::alloc_insn_page() to remove writable
permissions when STRICT_MODULE_RWX is on.

Add definition of EXECMEM_KRPOBES to execmem_params to allow using the
generic kprobes::alloc_insn_page() with the desired permissions.

As powerpc uses breakpoint instructions to inject kprobes, it does not
need to constrain kprobe allocations to the modules area and can use the
entire vmalloc address space.

Signed-off-by: Mike Rapoport (IBM) <[email-masked]>
---
 arch/powerpc/kernel/kprobes.c | 14 --------------
 arch/powerpc/kernel/module.c  | 11 +++++++++++
 2 files changed, 11 insertions(+), 14 deletions(-)

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 62228c7072a2..14c5ddec3056 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -126,20 +126,6 @@ kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offse
 	return (kprobe_opcode_t *)(addr + offset);
 }
 
-void *alloc_insn_page(void)
-{
-	void *page;
-
-	page = execmem_text_alloc(EXECMEM_KPROBES, PAGE_SIZE);
-	if (!page)
-		return NULL;
-
-	if (strict_module_rwx_enabled())
-		set_memory_rox((unsigned long)page, 1);
-
-	return page;
-}
-
 int arch_prepare_kprobe(struct kprobe *p)
 {
 	int ret = 0;
diff --git a/arch/powerpc/kernel/module.c b/arch/powerpc/kernel/module.c
index 824d9541a310..bf2c62aef628 100644
--- a/arch/powerpc/kernel/module.c
+++ b/arch/powerpc/kernel/module.c
@@ -95,6 +95,9 @@ static struct execmem_params execmem_params __ro_after_init = {
 		[EXECMEM_DEFAULT] = {
 			.alignment = 1,
 		},
+		[EXECMEM_KPROBES] = {
+			.alignment = 1,
+		},
 		[EXECMEM_MODULE_DATA] = {
 			.alignment = 1,
 		},
@@ -135,5 +138,13 @@ struct execmem_params __init *execmem_arch_params(void)
 
 	range->pgprot = prot;
 
+	execmem_params.ranges[EXECMEM_KPROBES].start = VMALLOC_START;
+	execmem_params.ranges[EXECMEM_KPROBES].start = VMALLOC_END;
+
+	if (strict_module_rwx_enabled())
+		execmem_params.ranges[EXECMEM_KPROBES].pgprot = PAGE_KERNEL_ROX;
+	else
+		execmem_params.ranges[EXECMEM_KPROBES].pgprot = PAGE_KERNEL_EXEC;
+
 	return &execmem_params;
 }
-- 
2.39.2