[PATCH v2 14/19] arm64: entry: handle all vectors with C

Mark Rutland
2021-05-19T13:10:55Z

We have 16 architectural exception vectors, and depending on kernel
configuration we handle 8 or 12 of these with C code, and we handle 8 or
4 of these as sepcial cases in the entry assembly.

It would be nicer if the entry assembly were uniform for all exceptions,
and we deferred any specific handling of the exceptions to C code. This
way the entry assembly can be more easily templated without ifdeffery or
special cases, and it's easier to modify the handling of these cases in
future (e.g. to dump additional registers other context).

This patch reworks the entry code so that we always have a C handle for
every architectural exception vector, with the entry assembly being
completely uniform. We now have to handle exceptions from EL1t and EL1h,
and also have to handle exceptions from AArch32 even when the kernel is
built without CONFIG_COMPAT. To make this clear and to simplify
templating, we rename the top-level exception handlers with a consistent
naming scheme:

asm: <el>_<regsize>_<type>
c: <el>_<regsize>_<type>_handler

.. where:

<el> is `el1t`, `el1h`, or `el0`
<regsize> is `64` or `32`
<type> is `sync`, `irq`, `fiq`, or `error`

... e.g.

asm: el1h_64_sync
c: el1h_64_sync_handler

... with lower-level handlers simply using "el1" and "compat" as today.

For unexpected exceptions, this information is passed to
panic_unandled(), so it can report the specific vector an unexpected
exception was taken from, e.g.

| Unexpected 64-bit el1t sync exception

For vectors we never expect to enter legitimately, the C code is
gnerated using a macro to avoid code duplication.

The `kernel_ventry` and `entry_handler` assembly macros are update to
handle the new naming scheme. In theory it should be possible to
generate the entry functions at the same time as the vectors using a
single table, but this will require reworking the linker script to split
the two into separate sections, so for now we duplicate the two.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
---
arch/arm64/include/asm/exception.h | 31 +++++---
arch/arm64/kernel/entry-common.c | 51 +++++++------
arch/arm64/kernel/entry.S | 146 ++++++++++++-------------------------
3 files changed, 92 insertions(+), 136 deletions(-)

diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h
index 4284ee57a9a5..40a3a20dca1c 100644
--- a/arch/arm64/include/asm/exception.h
+++ b/arch/arm64/include/asm/exception.h
@@ -31,18 +31,25 @@ static inline u32 disr_to_esr(u64 disr)
return esr;
}

-asmlinkage void el1_sync_handler(struct pt_regs *regs);
-asmlinkage void el1_irq_handler(struct pt_regs *regs);
-asmlinkage void el1_fiq_handler(struct pt_regs *regs);
-asmlinkage void el1_error_handler(struct pt_regs *regs);
-asmlinkage void el0_sync_handler(struct pt_regs *regs);
-asmlinkage void el0_irq_handler(struct pt_regs *regs);
-asmlinkage void el0_fiq_handler(struct pt_regs *regs);
-asmlinkage void el0_error_handler(struct pt_regs *regs);
-asmlinkage void el0_sync_compat_handler(struct pt_regs *regs);
-asmlinkage void el0_irq_compat_handler(struct pt_regs *regs);
-asmlinkage void el0_fiq_compat_handler(struct pt_regs *regs);
-asmlinkage void el0_error_compat_handler(struct pt_regs *regs);
+asmlinkage void el1t_64_sync_handler(struct pt_regs *regs);
+asmlinkage void el1t_64_irq_handler(struct pt_regs *regs);
+asmlinkage void el1t_64_fiq_handler(struct pt_regs *regs);
+asmlinkage void el1t_64_error_handler(struct pt_regs *regs);
+
+asmlinkage void el1h_64_sync_handler(struct pt_regs *regs);
+asmlinkage void el1h_64_irq_handler(struct pt_regs *regs);
+asmlinkage void el1h_64_fiq_handler(struct pt_regs *regs);
+asmlinkage void el1h_64_error_handler(struct pt_regs *regs);
+
+asmlinkage void el0_64_sync_handler(struct pt_regs *regs);
+asmlinkage void el0_64_irq_handler(struct pt_regs *regs);
+asmlinkage void el0_64_fiq_handler(struct pt_regs *regs);
+asmlinkage void el0_64_error_handler(struct pt_regs *regs);
+
+asmlinkage void el0_32_sync_handler(struct pt_regs *regs);
+asmlinkage void el0_32_irq_handler(struct pt_regs *regs);
+asmlinkage void el0_32_fiq_handler(struct pt_regs *regs);
+asmlinkage void el0_32_error_handler(struct pt_regs *regs);

asmlinkage void call_on_irq_stack(struct pt_regs *regs,
void (*func)(struct pt_regs *));
diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
index b43ef1a918a4..6f1caec913a9 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c
@@ -175,16 +175,11 @@ static void noinstr __panic_unhandled(struct pt_regs *regs, const char *vector,
panic("Unhandled exception");
}

-asmlinkage void noinstr bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
-{
- const char *handler[] = {
- "Synchronous Abort",
- "IRQ",
- "FIQ",
- "Error"
- };
-
- __panic_unhandled(regs, handler[reason], esr);
+#define UNHANDLED(el, regsize, vector) \
+asmlinkage void noinstr el##_##regsize##_##vector##_handler(struct pt_regs *regs) \
+{ \
+ const char *desc = #regsize "-bit " #el " " #vector; \
+ __panic_unhandled(regs, desc, read_sysreg(esr_el1)); \
}

#ifdef CONFIG_ARM64_ERRATUM_1463225
@@ -236,6 +231,11 @@ static bool cortex_a76_erratum_1463225_debug_handler(struct pt_regs *regs)
}
#endif /* CONFIG_ARM64_ERRATUM_1463225 */

+UNHANDLED(el1t, 64, sync)
+UNHANDLED(el1t, 64, irq)
+UNHANDLED(el1t, 64, fiq)
+UNHANDLED(el1t, 64, error)
+
static void noinstr el1_abort(struct pt_regs *regs, unsigned long esr)
{
unsigned long far = read_sysreg(far_el1);
@@ -271,7 +271,7 @@ static void noinstr el1_inv(struct pt_regs *regs, unsigned long esr)
{
enter_from_kernel_mode(regs);
local_daif_inherit(regs);
- bad_mode(regs, 0, esr);
+ __panic_unhandled(regs, "el1h sync", esr);
local_daif_mask();
exit_to_kernel_mode(regs);
}
@@ -319,7 +319,7 @@ static void noinstr el1_fpac(struct pt_regs *regs, unsigned long esr)
exit_to_kernel_mode(regs);
}

-asmlinkage void noinstr el1_sync_handler(struct pt_regs *regs)
+asmlinkage void noinstr el1h_64_sync_handler(struct pt_regs *regs)
{
unsigned long esr = read_sysreg(esr_el1);

@@ -364,17 +364,17 @@ static void noinstr el1_interrupt(struct pt_regs *regs,
exit_el1_irq_or_nmi(regs);
}

-asmlinkage void noinstr el1_irq_handler(struct pt_regs *regs)
+asmlinkage void noinstr el1h_64_irq_handler(struct pt_regs *regs)
{
el1_interrupt(regs, handle_arch_irq);
}

-asmlinkage void noinstr el1_fiq_handler(struct pt_regs *regs)
+asmlinkage void noinstr el1h_64_fiq_handler(struct pt_regs *regs)
{
el1_interrupt(regs, handle_arch_fiq);
}

-asmlinkage void noinstr el1_error_handler(struct pt_regs *regs)
+asmlinkage void noinstr el1h_64_error_handler(struct pt_regs *regs)
{
unsigned long esr = read_sysreg(esr_el1);

@@ -520,7 +520,7 @@ static void noinstr el0_fpac(struct pt_regs *regs, unsigned long esr)
do_ptrauth_fault(regs, esr);
}

-asmlinkage void noinstr el0_sync_handler(struct pt_regs *regs)
+asmlinkage void noinstr el0_64_sync_handler(struct pt_regs *regs)
{
unsigned long esr = read_sysreg(esr_el1);

@@ -591,7 +591,7 @@ static void noinstr __el0_irq_handler_common(struct pt_regs *regs)
el0_interrupt(regs, handle_arch_irq);
}

-asmlinkage void noinstr el0_irq_handler(struct pt_regs *regs)
+asmlinkage void noinstr el0_64_irq_handler(struct pt_regs *regs)
{
__el0_irq_handler_common(regs);
}
@@ -601,7 +601,7 @@ static void noinstr __el0_fiq_handler_common(struct pt_regs *regs)
el0_interrupt(regs, handle_arch_fiq);
}

-asmlinkage void noinstr el0_fiq_handler(struct pt_regs *regs)
+asmlinkage void noinstr el0_64_fiq_handler(struct pt_regs *regs)
{
__el0_fiq_handler_common(regs);
}
@@ -618,7 +618,7 @@ static void __el0_error_handler_common(struct pt_regs *regs)
local_daif_restore(DAIF_PROCCTX);
}

-asmlinkage void noinstr el0_error_handler(struct pt_regs *regs)
+asmlinkage void noinstr el0_64_error_handler(struct pt_regs *regs)
{
__el0_error_handler_common(regs);
}
@@ -638,7 +638,7 @@ static void noinstr el0_svc_compat(struct pt_regs *regs)
do_el0_svc_compat(regs);
}

-asmlinkage void noinstr el0_sync_compat_handler(struct pt_regs *regs)
+asmlinkage void noinstr el0_32_sync_handler(struct pt_regs *regs)
{
unsigned long esr = read_sysreg(esr_el1);

@@ -682,18 +682,23 @@ asmlinkage void noinstr el0_sync_compat_handler(struct pt_regs *regs)
}
}

-asmlinkage void noinstr el0_irq_compat_handler(struct pt_regs *regs)
+asmlinkage void noinstr el0_32_irq_handler(struct pt_regs *regs)
{
__el0_irq_handler_common(regs);
}

-asmlinkage void noinstr el0_fiq_compat_handler(struct pt_regs *regs)
+asmlinkage void noinstr el0_32_fiq_handler(struct pt_regs *regs)
{
__el0_fiq_handler_common(regs);
}

-asmlinkage void noinstr el0_error_compat_handler(struct pt_regs *regs)
+asmlinkage void noinstr el0_32_error_handler(struct pt_regs *regs)
{
__el0_error_handler_common(regs);
}
+#else /* CONFIG_COMPAT */
+UNHANDLED(el0, 32, sync)
+UNHANDLED(el0, 32, irq)
+UNHANDLED(el0, 32, fiq)
+UNHANDLED(el0, 32, error)
#endif /* CONFIG_COMPAT */
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index d4f80b9df621..257e8192e8d8 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -51,16 +51,7 @@
.endr
.endm

-/*
- * Bad Abort numbers
- *-----------------
- */
-#define BAD_SYNC 0
-#define BAD_IRQ 1
-#define BAD_FIQ 2
-#define BAD_ERROR 3
-
- .macro kernel_ventry, el:req, regsize:req, label:req
+ .macro kernel_ventry, el:req, ht, regsize:req, label:req
.align 7
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
.if \el == 0
@@ -87,7 +78,7 @@ alternative_else_nop_endif
tbnz x0, #THREAD_SHIFT, 0f
sub x0, sp, x0 // x0'' = sp' - x0' = (sp + x0) - sp = x0
sub sp, sp, x0 // sp'' = sp' - x0 = (sp + x0) - x0 = sp
- b el\()\el\()_\label
+ b el\el\ht\()_\regsize\()_\label

0:
/*
@@ -119,7 +110,7 @@ alternative_else_nop_endif
sub sp, sp, x0
mrs x0, tpidrro_el0
#endif
- b el\()\el\()_\label
+ b el\el\ht\()_\regsize\()_\label
.endm

.macro tramp_alias, dst, sym
@@ -510,32 +501,25 @@ tsk .req x28 // current thread_info

.align 11
SYM_CODE_START(vectors)
- kernel_ventry 1, 64, sync_invalid // Synchronous EL1t
- kernel_ventry 1, 64, irq_invalid // IRQ EL1t
- kernel_ventry 1, 64, fiq_invalid // FIQ EL1t
- kernel_ventry 1, 64, error_invalid // Error EL1t
-
- kernel_ventry 1, 64, sync // Synchronous EL1h
- kernel_ventry 1, 64, irq // IRQ EL1h
- kernel_ventry 1, 64, fiq // FIQ EL1h
- kernel_ventry 1, 64, error // Error EL1h
-
- kernel_ventry 0, 64, sync // Synchronous 64-bit EL0
- kernel_ventry 0, 64, irq // IRQ 64-bit EL0
- kernel_ventry 0, 64, fiq // FIQ 64-bit EL0
- kernel_ventry 0, 64, error // Error 64-bit EL0
-
-#ifdef CONFIG_COMPAT
- kernel_ventry 0, 32, sync_compat // Synchronous 32-bit EL0
- kernel_ventry 0, 32, irq_compat // IRQ 32-bit EL0
- kernel_ventry 0, 32, fiq_compat // FIQ 32-bit EL0
- kernel_ventry 0, 32, error_compat // Error 32-bit EL0
-#else
- kernel_ventry 0, 32, sync_invalid // Synchronous 32-bit EL0
- kernel_ventry 0, 32, irq_invalid // IRQ 32-bit EL0
- kernel_ventry 0, 32, fiq_invalid // FIQ 32-bit EL0
- kernel_ventry 0, 32, error_invalid // Error 32-bit EL0
-#endif
+ kernel_ventry 1, t, 64, sync // Synchronous EL1t
+ kernel_ventry 1, t, 64, irq // IRQ EL1t
+ kernel_ventry 1, t, 64, fiq // FIQ EL1h
+ kernel_ventry 1, t, 64, error // Error EL1t
+
+ kernel_ventry 1, h, 64, sync // Synchronous EL1h
+ kernel_ventry 1, h, 64, irq // IRQ EL1h
+ kernel_ventry 1, h, 64, fiq // FIQ EL1h
+ kernel_ventry 1, h, 64, error // Error EL1h
+
+ kernel_ventry 0, , 64, sync // Synchronous 64-bit EL0
+ kernel_ventry 0, , 64, irq // IRQ 64-bit EL0
+ kernel_ventry 0, , 64, fiq // FIQ 64-bit EL0
+ kernel_ventry 0, , 64, error // Error 64-bit EL0
+
+ kernel_ventry 0, , 32, sync // Synchronous 32-bit EL0
+ kernel_ventry 0, , 32, irq // IRQ 32-bit EL0
+ kernel_ventry 0, , 32, fiq // FIQ 32-bit EL0
+ kernel_ventry 0, , 32, error // Error 32-bit EL0
SYM_CODE_END(vectors)

#ifdef CONFIG_VMAP_STACK
@@ -566,83 +550,43 @@ __bad_stack:
ASM_BUG()
#endif /* CONFIG_VMAP_STACK */

-/*
- * Invalid mode handlers
- */
- .macro inv_entry, el, reason, regsize = 64
- kernel_entry \el, \regsize
- mov x0, sp
- mov x1, #\reason
- mrs x2, esr_el1
- bl bad_mode
- ASM_BUG()
- .endm
-
-SYM_CODE_START_LOCAL(el0_sync_invalid)
- inv_entry 0, BAD_SYNC
-SYM_CODE_END(el0_sync_invalid)
-
-SYM_CODE_START_LOCAL(el0_irq_invalid)
- inv_entry 0, BAD_IRQ
-SYM_CODE_END(el0_irq_invalid)
-
-SYM_CODE_START_LOCAL(el0_fiq_invalid)
- inv_entry 0, BAD_FIQ
-SYM_CODE_END(el0_fiq_invalid)
-
-SYM_CODE_START_LOCAL(el0_error_invalid)
- inv_entry 0, BAD_ERROR
-SYM_CODE_END(el0_error_invalid)

-SYM_CODE_START_LOCAL(el1_sync_invalid)
- inv_entry 1, BAD_SYNC
-SYM_CODE_END(el1_sync_invalid)
-
-SYM_CODE_START_LOCAL(el1_irq_invalid)
- inv_entry 1, BAD_IRQ
-SYM_CODE_END(el1_irq_invalid)
-
-SYM_CODE_START_LOCAL(el1_fiq_invalid)
- inv_entry 1, BAD_FIQ
-SYM_CODE_END(el1_fiq_invalid)
-
-SYM_CODE_START_LOCAL(el1_error_invalid)
- inv_entry 1, BAD_ERROR
-SYM_CODE_END(el1_error_invalid)
-
- .macro entry_handler el:req, regsize:req, label:req
+ .macro entry_handler el:req, ht, regsize:req, label:req
.align 6
-SYM_CODE_START_LOCAL_NOALIGN(el\el\()_\label)
+SYM_CODE_START_LOCAL_NOALIGN(el\el\ht\()_\regsize\()_\label)
kernel_entry \el, \regsize
mov x0, sp
- bl el\el\()_\label\()_handler
+ bl el\el\ht\()_\regsize\()_\label\()_handler
.if \el == 0
b ret_to_user
.else
b ret_to_kernel
.endif
-SYM_CODE_END(el\el\()_\label)
+SYM_CODE_END(el\el\ht\()_\regsize\()_\label)
.endm

/*
* Early exception handlers
*/
- entry_handler 1, 64, sync
- entry_handler 1, 64, irq
- entry_handler 1, 64, fiq
- entry_handler 1, 64, error
-
- entry_handler 0, 64, sync
- entry_handler 0, 64, irq
- entry_handler 0, 64, fiq
- entry_handler 0, 64, error
-
-#ifdef CONFIG_COMPAT
- entry_handler 0, 32, sync_compat
- entry_handler 0, 32, irq_compat
- entry_handler 0, 32, fiq_compat
- entry_handler 0, 32, error_compat
-#endif
+ entry_handler 1, t, 64, sync
+ entry_handler 1, t, 64, irq
+ entry_handler 1, t, 64, fiq
+ entry_handler 1, t, 64, error
+
+ entry_handler 1, h, 64, sync
+ entry_handler 1, h, 64, irq
+ entry_handler 1, h, 64, fiq
+ entry_handler 1, h, 64, error
+
+ entry_handler 0, , 64, sync
+ entry_handler 0, , 64, irq
+ entry_handler 0, , 64, fiq
+ entry_handler 0, , 64, error
+
+ entry_handler 0, , 32, sync
+ entry_handler 0, , 32, irq
+ entry_handler 0, , 32, fiq
+ entry_handler 0, , 32, error

SYM_CODE_START_LOCAL(ret_to_kernel)
kernel_exit 1