From: Ard Biesheuvel <ardb@kernel.org>
To: linux@armlinux.org.uk
Cc: linux-arm-kernel@lists.infradead.org,
Ard Biesheuvel <ardb@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Kees Cook <keescook@chromium.org>,
Keith Packard <keithpac@amazon.com>,
Linus Walleij <linus.walleij@linaro.org>
Subject: [PATCH 05/10] ARM: unwind: support unwinding across multiple stacks
Date: Tue, 21 Sep 2021 11:54:03 +0200 [thread overview]
Message-ID: <20210921095408.133210-6-ardb@kernel.org> (raw)
In-Reply-To: <20210921095408.133210-1-ardb@kernel.org>
Implement support in the unwinder for dealing with multiple stacks.
This will be needed once we add support for IRQ stacks, or for the
overflow stack used by the vmap'ed stacks code.
This involves tracking the unwind opcodes that either update the virtual
stack pointer from another virtual register, or perform an explicit
subtract on the virtual stack pointer, and updating the low and high
bounds that we use to sanitize the stack pointer accordingly.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/arm/kernel/unwind.c | 25 +++++++++++++-------
1 file changed, 16 insertions(+), 9 deletions(-)
diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c
index 59fdf257bf8b..9cb9af3fc433 100644
--- a/arch/arm/kernel/unwind.c
+++ b/arch/arm/kernel/unwind.c
@@ -52,6 +52,7 @@ EXPORT_SYMBOL(__aeabi_unwind_cpp_pr2);
struct unwind_ctrl_block {
unsigned long vrs[16]; /* virtual register set */
const unsigned long *insn; /* pointer to the current instructions word */
+ unsigned long sp_low; /* lowest value of sp allowed */
unsigned long sp_high; /* highest value of sp allowed */
/*
* 1 : check for stack overflow for each register pop.
@@ -256,8 +257,12 @@ static int unwind_exec_pop_subset_r4_to_r13(struct unwind_ctrl_block *ctrl,
mask >>= 1;
reg++;
}
- if (!load_sp)
+ if (!load_sp) {
ctrl->vrs[SP] = (unsigned long)vsp;
+ } else {
+ ctrl->sp_low = ctrl->vrs[SP];
+ ctrl->sp_high = ALIGN(ctrl->sp_low, THREAD_SIZE);
+ }
return URC_OK;
}
@@ -313,9 +318,10 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
if ((insn & 0xc0) == 0x00)
ctrl->vrs[SP] += ((insn & 0x3f) << 2) + 4;
- else if ((insn & 0xc0) == 0x40)
+ else if ((insn & 0xc0) == 0x40) {
ctrl->vrs[SP] -= ((insn & 0x3f) << 2) + 4;
- else if ((insn & 0xf0) == 0x80) {
+ ctrl->sp_low = ctrl->vrs[SP];
+ } else if ((insn & 0xf0) == 0x80) {
unsigned long mask;
insn = (insn << 8) | unwind_get_byte(ctrl);
@@ -330,9 +336,11 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
if (ret)
goto error;
} else if ((insn & 0xf0) == 0x90 &&
- (insn & 0x0d) != 0x0d)
+ (insn & 0x0d) != 0x0d) {
ctrl->vrs[SP] = ctrl->vrs[insn & 0x0f];
- else if ((insn & 0xf0) == 0xa0) {
+ ctrl->sp_low = ctrl->vrs[SP];
+ ctrl->sp_high = ALIGN(ctrl->sp_low, THREAD_SIZE);
+ } else if ((insn & 0xf0) == 0xa0) {
ret = unwind_exec_pop_r4_to_rN(ctrl, insn);
if (ret)
goto error;
@@ -375,13 +383,12 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
*/
int unwind_frame(struct stackframe *frame)
{
- unsigned long low;
const struct unwind_idx *idx;
struct unwind_ctrl_block ctrl;
/* store the highest address on the stack to avoid crossing it*/
- low = frame->sp;
- ctrl.sp_high = ALIGN(low, THREAD_SIZE);
+ ctrl.sp_low = frame->sp;
+ ctrl.sp_high = ALIGN(ctrl.sp_low, THREAD_SIZE);
pr_debug("%s(pc = %08lx lr = %08lx sp = %08lx)\n", __func__,
frame->pc, frame->lr, frame->sp);
@@ -437,7 +444,7 @@ int unwind_frame(struct stackframe *frame)
urc = unwind_exec_insn(&ctrl);
if (urc < 0)
return urc;
- if (ctrl.vrs[SP] < low || ctrl.vrs[SP] >= ctrl.sp_high)
+ if (ctrl.vrs[SP] < ctrl.sp_low || ctrl.vrs[SP] > ctrl.sp_high)
return -URC_FAILURE;
}
--
2.30.2
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next prev parent reply other threads:[~2021-09-21 9:57 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-21 9:53 [PATCH 00/10] ARM: add support for IRQ stacks Ard Biesheuvel
2021-09-21 9:53 ` [PATCH 01/10] ARM: fix incorrect use of get_kernel_nofault() Ard Biesheuvel
2021-09-21 10:39 ` Arnd Bergmann
2021-09-21 14:02 ` Russell King (Oracle)
2021-09-21 14:33 ` Ard Biesheuvel
2021-09-21 9:54 ` [PATCH 02/10] ARM: remove some dead code Ard Biesheuvel
2021-09-21 9:54 ` [PATCH 03/10] ARM: assembler: introduce bl_r and bl_m macros Ard Biesheuvel
2021-09-21 9:54 ` [PATCH 04/10] ARM: optimize indirect call to handle_arch_irq for v7 cores Ard Biesheuvel
2021-09-21 9:54 ` Ard Biesheuvel [this message]
2021-09-21 9:54 ` [PATCH 06/10] ARM: export dump_mem() to other objects Ard Biesheuvel
2021-09-21 9:54 ` [PATCH 07/10] ARM: unwind: dump exception stack from calling frame Ard Biesheuvel
2021-09-21 9:54 ` [PATCH 08/10] ARM: implement IRQ stacks Ard Biesheuvel
2021-09-21 9:54 ` [PATCH 09/10] ARM: call_with_stack: add unwind support Ard Biesheuvel
2021-09-21 9:54 ` [PATCH 10/10] ARM: run softirqs on the per-CPU IRQ stack Ard Biesheuvel
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