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authorVitaly Wool <vitaly.wool@konsulko.com>2021-05-31 11:53:42 +0300
committerPalmer Dabbelt <palmerdabbelt@google.com>2021-06-11 02:16:06 +0300
commit5e63215c2f64079fbd011df5005c8bea63f149c2 (patch)
tree521335babc29f534c56570d246aed170ddc26822
parent160ce364167fabf8df5bebfff1b38fd5d8c146c9 (diff)
downloadlinux-5e63215c2f64079fbd011df5005c8bea63f149c2.tar.xz
riscv: xip: support runtime trap patching
RISCV_ERRATA_ALTERNATIVE patches text at runtime which is currently not possible when the kernel is executed from the flash in XIP mode. Since runtime patching concerns only traps at the moment, let's just have all the traps reside in RAM anyway if RISCV_ERRATA_ALTERNATIVE is set. Thus, these functions will be patch-able even when the .text section is in flash. Signed-off-by: Vitaly Wool <vitaly.wool@konsulko.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
-rw-r--r--arch/riscv/kernel/traps.c13
-rw-r--r--arch/riscv/kernel/vmlinux-xip.lds.S15
2 files changed, 23 insertions, 5 deletions
diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index 0721b9798595..7bc88d8aab97 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -86,8 +86,13 @@ static void do_trap_error(struct pt_regs *regs, int signo, int code,
}
}
+#if defined (CONFIG_XIP_KERNEL) && defined (CONFIG_RISCV_ERRATA_ALTERNATIVE)
+#define __trap_section __section(".xip.traps")
+#else
+#define __trap_section
+#endif
#define DO_ERROR_INFO(name, signo, code, str) \
-asmlinkage __visible void name(struct pt_regs *regs) \
+asmlinkage __visible __trap_section void name(struct pt_regs *regs) \
{ \
do_trap_error(regs, signo, code, regs->epc, "Oops - " str); \
}
@@ -111,7 +116,7 @@ DO_ERROR_INFO(do_trap_store_misaligned,
int handle_misaligned_load(struct pt_regs *regs);
int handle_misaligned_store(struct pt_regs *regs);
-asmlinkage void do_trap_load_misaligned(struct pt_regs *regs)
+asmlinkage void __trap_section do_trap_load_misaligned(struct pt_regs *regs)
{
if (!handle_misaligned_load(regs))
return;
@@ -119,7 +124,7 @@ asmlinkage void do_trap_load_misaligned(struct pt_regs *regs)
"Oops - load address misaligned");
}
-asmlinkage void do_trap_store_misaligned(struct pt_regs *regs)
+asmlinkage void __trap_section do_trap_store_misaligned(struct pt_regs *regs)
{
if (!handle_misaligned_store(regs))
return;
@@ -146,7 +151,7 @@ static inline unsigned long get_break_insn_length(unsigned long pc)
return GET_INSN_LENGTH(insn);
}
-asmlinkage __visible void do_trap_break(struct pt_regs *regs)
+asmlinkage __visible __trap_section void do_trap_break(struct pt_regs *regs)
{
#ifdef CONFIG_KPROBES
if (kprobe_single_step_handler(regs))
diff --git a/arch/riscv/kernel/vmlinux-xip.lds.S b/arch/riscv/kernel/vmlinux-xip.lds.S
index 4b29b9917f99..a3ff09c4c3f9 100644
--- a/arch/riscv/kernel/vmlinux-xip.lds.S
+++ b/arch/riscv/kernel/vmlinux-xip.lds.S
@@ -99,9 +99,22 @@ SECTIONS
}
PERCPU_SECTION(L1_CACHE_BYTES)
- . = ALIGN(PAGE_SIZE);
+ . = ALIGN(8);
+ .alternative : {
+ __alt_start = .;
+ *(.alternative)
+ __alt_end = .;
+ }
__init_end = .;
+ . = ALIGN(16);
+ .xip.traps : {
+ __xip_traps_start = .;
+ *(.xip.traps)
+ __xip_traps_end = .;
+ }
+
+ . = ALIGN(PAGE_SIZE);
.sdata : {
__global_pointer$ = . + 0x800;
*(.sdata*)