[PATCH v4 3/6] riscv: Move global pointer loading to a macro
Sami Tolvanen
samitolvanen at google.com
Wed Sep 27 15:48:01 PDT 2023
In Clang 17, -fsanitize=shadow-call-stack uses the newly declared
platform register gp for storing shadow call stack pointers. As
this is obviously incompatible with gp relaxation, in preparation
for CONFIG_SHADOW_CALL_STACK support, move global pointer loading
to a single macro, which we can cleanly disable when SCS is used
instead.
Link: https://reviews.llvm.org/rGaa1d2693c256
Link: https://github.com/riscv-non-isa/riscv-elf-psabi-doc/commit/a484e843e6eeb51f0cb7b8819e50da6d2444d769
Signed-off-by: Sami Tolvanen <samitolvanen at google.com>
Tested-by: Nathan Chancellor <nathan at kernel.org>
---
arch/riscv/include/asm/asm.h | 8 ++++++++
arch/riscv/kernel/entry.S | 6 ++----
arch/riscv/kernel/head.S | 15 +++------------
arch/riscv/kernel/suspend_entry.S | 5 +----
4 files changed, 14 insertions(+), 20 deletions(-)
diff --git a/arch/riscv/include/asm/asm.h b/arch/riscv/include/asm/asm.h
index 8e446be2d57c..f34dd1a526a1 100644
--- a/arch/riscv/include/asm/asm.h
+++ b/arch/riscv/include/asm/asm.h
@@ -109,6 +109,14 @@
REG_L \dst, 0(\dst)
.endm
+/* load __global_pointer to gp */
+.macro load_global_pointer
+.option push
+.option norelax
+ la gp, __global_pointer$
+.option pop
+.endm
+
/* save all GPs except x1 ~ x5 */
.macro save_from_x6_to_x31
REG_S x6, PT_T1(sp)
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index a306562636e4..6215dcf2e83b 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -75,10 +75,8 @@ _save_context:
csrw CSR_SCRATCH, x0
/* Load the global pointer */
-.option push
-.option norelax
- la gp, __global_pointer$
-.option pop
+ load_global_pointer
+
move a0, sp /* pt_regs */
la ra, ret_from_exception
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 3710ea5d160f..a0484d95d8fb 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -110,10 +110,7 @@ relocate_enable_mmu:
csrw CSR_TVEC, a0
/* Reload the global pointer */
-.option push
-.option norelax
- la gp, __global_pointer$
-.option pop
+ load_global_pointer
/*
* Switch to kernel page tables. A full fence is necessary in order to
@@ -134,10 +131,7 @@ secondary_start_sbi:
csrw CSR_IP, zero
/* Load the global pointer */
- .option push
- .option norelax
- la gp, __global_pointer$
- .option pop
+ load_global_pointer
/*
* Disable FPU & VECTOR to detect illegal usage of
@@ -228,10 +222,7 @@ pmp_done:
#endif /* CONFIG_RISCV_M_MODE */
/* Load the global pointer */
-.option push
-.option norelax
- la gp, __global_pointer$
-.option pop
+ load_global_pointer
/*
* Disable FPU & VECTOR to detect illegal usage of
diff --git a/arch/riscv/kernel/suspend_entry.S b/arch/riscv/kernel/suspend_entry.S
index f7960c7c5f9e..d5cf8b575777 100644
--- a/arch/riscv/kernel/suspend_entry.S
+++ b/arch/riscv/kernel/suspend_entry.S
@@ -61,10 +61,7 @@ END(__cpu_suspend_enter)
SYM_TYPED_FUNC_START(__cpu_resume_enter)
/* Load the global pointer */
- .option push
- .option norelax
- la gp, __global_pointer$
- .option pop
+ load_global_pointer
#ifdef CONFIG_MMU
/* Save A0 and A1 */
--
2.42.0.515.g380fc7ccd1-goog
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