From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Douglas Anderson <dianders@chromium.org>,
Matthias Kaehlcke <mka@chromium.org>,
Will Deacon <will@kernel.org>,
Russell King <rmk+kernel@armlinux.org.uk>,
Sasha Levin <sashal@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH AUTOSEL 4.19 09/60] ARM: 8997/2: hw_breakpoint: Handle inexact watchpoint addresses
Date: Mon, 26 Oct 2020 20:03:24 -0400 [thread overview]
Message-ID: <20201027000415.1026364-9-sashal@kernel.org> (raw)
In-Reply-To: <20201027000415.1026364-1-sashal@kernel.org>
From: Douglas Anderson <dianders@chromium.org>
[ Upstream commit 22c9e58299e5f18274788ce54c03d4fb761e3c5d ]
This is commit fdfeff0f9e3d ("arm64: hw_breakpoint: Handle inexact
watchpoint addresses") but ported to arm32, which has the same
problem.
This problem was found by Android CTS tests, notably the
"watchpoint_imprecise" test [1]. I tested locally against a copycat
(simplified) version of the test though.
[1] https://android.googlesource.com/platform/bionic/+/master/tests/sys_ptrace_test.cpp
Link: https://lkml.kernel.org/r/20191019111216.1.I82eae759ca6dc28a245b043f485ca490e3015321@changeid
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm/kernel/hw_breakpoint.c | 100 +++++++++++++++++++++++---------
1 file changed, 72 insertions(+), 28 deletions(-)
diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index 8a8470d36c659..97fa9c1677576 100644
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -688,6 +688,40 @@ static void disable_single_step(struct perf_event *bp)
arch_install_hw_breakpoint(bp);
}
+/*
+ * Arm32 hardware does not always report a watchpoint hit address that matches
+ * one of the watchpoints set. It can also report an address "near" the
+ * watchpoint if a single instruction access both watched and unwatched
+ * addresses. There is no straight-forward way, short of disassembling the
+ * offending instruction, to map that address back to the watchpoint. This
+ * function computes the distance of the memory access from the watchpoint as a
+ * heuristic for the likelyhood that a given access triggered the watchpoint.
+ *
+ * See this same function in the arm64 platform code, which has the same
+ * problem.
+ *
+ * The function returns the distance of the address from the bytes watched by
+ * the watchpoint. In case of an exact match, it returns 0.
+ */
+static u32 get_distance_from_watchpoint(unsigned long addr, u32 val,
+ struct arch_hw_breakpoint_ctrl *ctrl)
+{
+ u32 wp_low, wp_high;
+ u32 lens, lene;
+
+ lens = __ffs(ctrl->len);
+ lene = __fls(ctrl->len);
+
+ wp_low = val + lens;
+ wp_high = val + lene;
+ if (addr < wp_low)
+ return wp_low - addr;
+ else if (addr > wp_high)
+ return addr - wp_high;
+ else
+ return 0;
+}
+
static int watchpoint_fault_on_uaccess(struct pt_regs *regs,
struct arch_hw_breakpoint *info)
{
@@ -697,23 +731,25 @@ static int watchpoint_fault_on_uaccess(struct pt_regs *regs,
static void watchpoint_handler(unsigned long addr, unsigned int fsr,
struct pt_regs *regs)
{
- int i, access;
- u32 val, ctrl_reg, alignment_mask;
+ int i, access, closest_match = 0;
+ u32 min_dist = -1, dist;
+ u32 val, ctrl_reg;
struct perf_event *wp, **slots;
struct arch_hw_breakpoint *info;
struct arch_hw_breakpoint_ctrl ctrl;
slots = this_cpu_ptr(wp_on_reg);
+ /*
+ * Find all watchpoints that match the reported address. If no exact
+ * match is found. Attribute the hit to the closest watchpoint.
+ */
+ rcu_read_lock();
for (i = 0; i < core_num_wrps; ++i) {
- rcu_read_lock();
-
wp = slots[i];
-
if (wp == NULL)
- goto unlock;
+ continue;
- info = counter_arch_bp(wp);
/*
* The DFAR is an unknown value on debug architectures prior
* to 7.1. Since we only allow a single watchpoint on these
@@ -722,33 +758,31 @@ static void watchpoint_handler(unsigned long addr, unsigned int fsr,
*/
if (debug_arch < ARM_DEBUG_ARCH_V7_1) {
BUG_ON(i > 0);
+ info = counter_arch_bp(wp);
info->trigger = wp->attr.bp_addr;
} else {
- if (info->ctrl.len == ARM_BREAKPOINT_LEN_8)
- alignment_mask = 0x7;
- else
- alignment_mask = 0x3;
-
- /* Check if the watchpoint value matches. */
- val = read_wb_reg(ARM_BASE_WVR + i);
- if (val != (addr & ~alignment_mask))
- goto unlock;
-
- /* Possible match, check the byte address select. */
- ctrl_reg = read_wb_reg(ARM_BASE_WCR + i);
- decode_ctrl_reg(ctrl_reg, &ctrl);
- if (!((1 << (addr & alignment_mask)) & ctrl.len))
- goto unlock;
-
/* Check that the access type matches. */
if (debug_exception_updates_fsr()) {
access = (fsr & ARM_FSR_ACCESS_MASK) ?
HW_BREAKPOINT_W : HW_BREAKPOINT_R;
if (!(access & hw_breakpoint_type(wp)))
- goto unlock;
+ continue;
}
+ val = read_wb_reg(ARM_BASE_WVR + i);
+ ctrl_reg = read_wb_reg(ARM_BASE_WCR + i);
+ decode_ctrl_reg(ctrl_reg, &ctrl);
+ dist = get_distance_from_watchpoint(addr, val, &ctrl);
+ if (dist < min_dist) {
+ min_dist = dist;
+ closest_match = i;
+ }
+ /* Is this an exact match? */
+ if (dist != 0)
+ continue;
+
/* We have a winner. */
+ info = counter_arch_bp(wp);
info->trigger = addr;
}
@@ -770,13 +804,23 @@ static void watchpoint_handler(unsigned long addr, unsigned int fsr,
* we can single-step over the watchpoint trigger.
*/
if (!is_default_overflow_handler(wp))
- goto unlock;
-
+ continue;
step:
enable_single_step(wp, instruction_pointer(regs));
-unlock:
- rcu_read_unlock();
}
+
+ if (min_dist > 0 && min_dist != -1) {
+ /* No exact match found. */
+ wp = slots[closest_match];
+ info = counter_arch_bp(wp);
+ info->trigger = addr;
+ pr_debug("watchpoint fired: address = 0x%x\n", info->trigger);
+ perf_bp_event(wp, regs);
+ if (is_default_overflow_handler(wp))
+ enable_single_step(wp, instruction_pointer(regs));
+ }
+
+ rcu_read_unlock();
}
static void watchpoint_single_step_handler(unsigned long pc)
--
2.25.1
next prev parent reply other threads:[~2020-10-27 0:05 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-27 0:03 [PATCH AUTOSEL 4.19 01/60] powerpc/powernv/smp: Fix spurious DBG() warning Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 02/60] powerpc: select ARCH_WANT_IRQS_OFF_ACTIVATE_MM Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 03/60] sparc64: remove mm_cpumask clearing to fix kthread_use_mm race Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 04/60] f2fs: add trace exit in exception path Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 05/60] f2fs: fix uninit-value in f2fs_lookup Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 06/60] f2fs: fix to check segment boundary during SIT page readahead Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 07/60] um: change sigio_spinlock to a mutex Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 08/60] MIPS: ftrace: Remove redundant #ifdef CONFIG_DYNAMIC_FTRACE Sasha Levin
2020-10-27 7:59 ` Sergei Shtylyov
2020-10-27 0:03 ` Sasha Levin [this message]
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 10/60] power: supply: bq27xxx: report "not charging" on all types Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 11/60] xfs: fix realtime bitmap/summary file truncation when growing rt volume Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 12/60] video: fbdev: pvr2fb: initialize variables Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 13/60] ath10k: start recovery process when payload length exceeds max htc length for sdio Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 14/60] ath10k: fix VHT NSS calculation when STBC is enabled Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 15/60] drm/brige/megachips: Add checking if ge_b850v3_lvds_init() is working correctly Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 16/60] media: videodev2.h: RGB BT2020 and HSV are always full range Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 17/60] media: platform: Improve queue set up flow for bug fixing Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 18/60] usb: typec: tcpm: During PR_SWAP, source caps should be sent only after tSwapSourceStart Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 19/60] media: tw5864: check status of tw5864_frameinterval_get Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 20/60] media: imx274: fix frame interval handling Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 21/60] mmc: via-sdmmc: Fix data race bug Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 22/60] drm/bridge/synopsys: dsi: add support for non-continuous HS clock Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 23/60] arm64: topology: Stop using MPIDR for topology information Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 24/60] printk: reduce LOG_BUF_SHIFT range for H8300 Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 25/60] ia64: kprobes: Use generic kretprobe trampoline handler Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 26/60] kgdb: Make "kgdbcon" work properly with "kgdb_earlycon" Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 27/60] media: uvcvideo: Fix dereference of out-of-bound list iterator Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 28/60] riscv: Define AT_VECTOR_SIZE_ARCH for ARCH_DLINFO Sasha Levin
2020-11-06 5:26 ` Palmer Dabbelt
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 29/60] cpufreq: sti-cpufreq: add stih418 support Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 30/60] USB: adutux: fix debugging Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 31/60] uio: free uio id after uio file node is freed Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 32/60] usb: xhci: omit duplicate actions when suspending a runtime suspended host Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 33/60] arm64/mm: return cpu_all_mask when node is NUMA_NO_NODE Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 34/60] xfs: don't free rt blocks when we're doing a REMAP bunmapi call Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 35/60] ACPI: Add out of bounds and numa_off protections to pxm_to_node() Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 36/60] genirq: Add stub for set_handle_irq() when !GENERIC_IRQ_MULTI_HANDLER Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 37/60] dm: change max_io_len() to use blk_max_size_offset() Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 38/60] drivers/net/wan/hdlc_fr: Correctly handle special skb->protocol values Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 39/60] bus/fsl_mc: Do not rely on caller to provide non NULL mc_io Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 40/60] power: supply: test_power: add missing newlines when printing parameters by sysfs Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 41/60] drm/amd/display: HDMI remote sink need mode validation for Linux Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 42/60] btrfs: fix replace of seed device Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 43/60] md/bitmap: md_bitmap_get_counter returns wrong blocks Sasha Levin
2020-10-27 0:03 ` [PATCH AUTOSEL 4.19 44/60] bnxt_en: Log unknown link speed appropriately Sasha Levin
2020-10-27 0:04 ` [PATCH AUTOSEL 4.19 45/60] rpmsg: glink: Use complete_all for open states Sasha Levin
2020-10-27 0:04 ` [PATCH AUTOSEL 4.19 46/60] clk: ti: clockdomain: fix static checker warning Sasha Levin
2020-10-27 0:04 ` [PATCH AUTOSEL 4.19 47/60] net: 9p: initialize sun_server.sun_path to have addr's value only when addr is valid Sasha Levin
2020-10-27 0:04 ` [PATCH AUTOSEL 4.19 48/60] drivers: watchdog: rdc321x_wdt: Fix race condition bugs Sasha Levin
2020-10-27 0:04 ` [PATCH AUTOSEL 4.19 49/60] ext4: Detect already used quota file early Sasha Levin
2020-10-27 0:04 ` [PATCH AUTOSEL 4.19 50/60] gfs2: add validation checks for size of superblock Sasha Levin
2020-10-27 0:04 ` [PATCH AUTOSEL 4.19 51/60] cifs: handle -EINTR in cifs_setattr Sasha Levin
2020-10-27 0:04 ` [PATCH AUTOSEL 4.19 52/60] arm64: dts: renesas: ulcb: add full-pwr-cycle-in-suspend into eMMC nodes Sasha Levin
2020-10-27 0:04 ` [PATCH AUTOSEL 4.19 53/60] ARM: dts: omap4: Fix sgx clock rate for 4430 Sasha Levin
2020-10-27 0:04 ` [PATCH AUTOSEL 4.19 54/60] memory: emif: Remove bogus debugfs error handling Sasha Levin
2020-10-27 0:04 ` [PATCH AUTOSEL 4.19 55/60] ARM: dts: s5pv210: remove DMA controller bus node name to fix dtschema warnings Sasha Levin
2020-10-27 0:04 ` [PATCH AUTOSEL 4.19 56/60] ARM: dts: s5pv210: move PMU node out of clock controller Sasha Levin
2020-10-27 0:04 ` [PATCH AUTOSEL 4.19 57/60] ARM: dts: s5pv210: remove dedicated 'audio-subsystem' node Sasha Levin
2020-10-27 0:04 ` [PATCH AUTOSEL 4.19 58/60] nbd: make the config put is called before the notifying the waiter Sasha Levin
2020-10-27 0:04 ` [PATCH AUTOSEL 4.19 59/60] sgl_alloc_order: fix memory leak Sasha Levin
2020-10-27 0:04 ` [PATCH AUTOSEL 4.19 60/60] nvme-rdma: fix crash when connect rejected Sasha Levin
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