-
Notifications
You must be signed in to change notification settings - Fork 4
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Pull in the patch from here: > espressif/esp-idf#6124 (comment) Which was applied to the espressif binutils-gdb fork here: > espressif/binutils-gdb@9a47478 Verified after the patch, loading a core file with a previously-truncated backtrace now shows the full backtrace.
- Loading branch information
Showing
4 changed files
with
276 additions
and
4 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,134 @@ | ||
| From 9a47478fa686eae204b905bbe0e6833965f207bd Mon Sep 17 00:00:00 2001 | ||
| From: Ivan Grokhotkov <[email protected]> | ||
| Date: Sun, 15 Aug 2021 13:38:51 +0500 | ||
| Subject: [PATCH] gdb: xtensa: fix backtrace interrupted by a noreturn call | ||
|
|
||
| This commit fixes an issue that the backtrace will be interrupted on a | ||
| frame where a noreturn function is called. This issue doesn't occur | ||
| for every call to noreturn functions, but only for calls such that: | ||
| - the call is the last instruction of the caller function | ||
| - the next function starts immediately after this call instruction; | ||
| in most cases this means that the caller function size is divisible | ||
| by 4 bytes, so no padding is added between the last instruction and | ||
| the next function. | ||
|
|
||
| For example, the following generated code will exhibit this issue: | ||
|
|
||
| esp_system_abort: | ||
| entry a1, 32 | ||
| movi.n a10, a2 | ||
| call8 panic_abort | ||
|
|
||
| some_other_function: | ||
| entry a1, 32 | ||
| ... | ||
|
|
||
| In this case, esp_system_abort function is 3 + 2 + 3 = 8 bytes long, | ||
| so no padding is required before "some_other_function". When the call | ||
| to panic_abort happens, the return address is set to the next | ||
| instruction, i.e. the "entry" instruction of "some_other_function". | ||
|
|
||
| The observed behavior is that the backtrace is interrupted: | ||
|
|
||
| #0 panic_abort (details=0x3ffb5c3b "abort() was called at PC 0x400d485f on core 0") | ||
| at $IDF_PATH/components/esp_system/panic.c:389 | ||
| #1 0x40084fb0 in esp_system_abort ( | ||
| details=0x3ffb5c3b "abort() was called at PC 0x400d485f on core 0") | ||
| at $IDF_PATH/components/esp_system/esp_system.c:129 | ||
| Backtrace stopped: previous frame identical to this frame (corrupt stack?) | ||
|
|
||
| The reason is that when the unwinder inspects the instruction at the | ||
| return address in the caller frame, the instruction is an ENTRY, | ||
| which is part of the next function. Previously it was considered that | ||
| the only case when this can happen is if the frame is the outermost | ||
| frame and the entry instruction hasn't executed yet. | ||
|
|
||
| This commit fixes that assumption, by checking additionally if the | ||
| instruction preceding ENTRY is a call. If it is, the frame is handled | ||
| as usual. | ||
| --- | ||
| gdb/xtensa-tdep.c | 51 ++++++++++++++++++++++++++++++++++++++++++----- | ||
| 1 file changed, 46 insertions(+), 5 deletions(-) | ||
|
|
||
| diff --git a/gdb/xtensa-tdep.c b/gdb/xtensa-tdep.c | ||
| index e18f7a18a5f..d318cfa551b 100644 | ||
| --- a/gdb/xtensa-tdep.c | ||
| +++ b/gdb/xtensa-tdep.c | ||
| @@ -1239,6 +1239,49 @@ xtensa_window_interrupt_frame_cache (struct frame_info *this_frame, | ||
| xtensa_frame_cache_t *cache, | ||
| CORE_ADDR pc); | ||
|
|
||
| +/* Check if the frame should be decoded as if it is the outermost frame, | ||
| + where the ENTRY instruction is about to be executed. */ | ||
| +static bool | ||
| +xtensa_is_frame_entry (struct gdbarch *gdbarch, CORE_ADDR pc) | ||
| +{ | ||
| + gdb_byte buf[4]; | ||
| + int insn; | ||
| + enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); | ||
| + | ||
| + LONGEST op1; | ||
| + if (!(safe_read_memory_integer (pc, 1, byte_order, &op1) | ||
| + && XTENSA_IS_ENTRY (gdbarch, op1))) | ||
| + return false; | ||
| + | ||
| + /* PC points to the ENTRY instruction. However this might be | ||
| + because the previous instruction belonged to another function, | ||
| + and that function was a call to "noreturn" function, e.g.: | ||
| + | ||
| + some_func: | ||
| + entry sp, 32 | ||
| + mov.n a10, a2 | ||
| + call8 panic | ||
| + // no retw.n because "panic" has noreturn attribute | ||
| + next_func: | ||
| + entry sp, 32 // <- return address | ||
| + ... | ||
| + | ||
| + In such case, we need to decode the frame as usual. | ||
| + The code below checks if the instruction at PC-3 is a call/callx. */ | ||
| + | ||
| + read_memory(pc - 3, buf, 3); | ||
| + insn = extract_unsigned_integer (buf, 3, byte_order); | ||
| + | ||
| + /* Decode call instruction. See comment in extract_call_winsize */ | ||
| + if ((byte_order == BFD_ENDIAN_LITTLE && | ||
| + (((insn & 0xf) == 0x5) || ((insn & 0xcf) == 0xc0))) || | ||
| + (byte_order == BFD_ENDIAN_BIG && | ||
| + (((insn >> 20) == 0x5) || (((insn >> 16) & 0xf3) == 0x03)))) | ||
| + return false; | ||
| + | ||
| + return true; | ||
| +} | ||
| + | ||
| static struct xtensa_frame_cache * | ||
| xtensa_frame_cache (struct frame_info *this_frame, void **this_cache) | ||
| { | ||
| @@ -1265,16 +1308,13 @@ xtensa_frame_cache (struct frame_info *this_frame, void **this_cache) | ||
|
|
||
| if (windowed) | ||
| { | ||
| - LONGEST op1; | ||
| - | ||
| /* Get WINDOWBASE, WINDOWSTART, and PS registers. */ | ||
| wb = get_frame_register_unsigned (this_frame, | ||
| gdbarch_tdep (gdbarch)->wb_regnum); | ||
| ws = get_frame_register_unsigned (this_frame, | ||
| gdbarch_tdep (gdbarch)->ws_regnum); | ||
|
|
||
| - if (safe_read_memory_integer (pc, 1, byte_order, &op1) | ||
| - && XTENSA_IS_ENTRY (gdbarch, op1)) | ||
| + if (xtensa_is_frame_entry(gdbarch, pc)) | ||
| { | ||
| int callinc = CALLINC (ps); | ||
| ra = get_frame_register_unsigned | ||
| @@ -1287,7 +1327,8 @@ xtensa_frame_cache (struct frame_info *this_frame, void **this_cache) | ||
| cache->prev_sp = get_frame_register_unsigned | ||
| (this_frame, gdbarch_tdep (gdbarch)->a0_base + 1); | ||
|
|
||
| - /* This only can be the outermost frame since we are | ||
| + /* xtensa_is_frame_entry has checked that the previous instruction | ||
| + is not a call, so this only can be the outermost frame where we are | ||
| just about to execute ENTRY. SP hasn't been set yet. | ||
| We can assume any frame size, because it does not | ||
| matter, and, let's fake frame base in cache. */ |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,134 @@ | ||
| From 9a47478fa686eae204b905bbe0e6833965f207bd Mon Sep 17 00:00:00 2001 | ||
| From: Ivan Grokhotkov <[email protected]> | ||
| Date: Sun, 15 Aug 2021 13:38:51 +0500 | ||
| Subject: [PATCH] gdb: xtensa: fix backtrace interrupted by a noreturn call | ||
|
|
||
| This commit fixes an issue that the backtrace will be interrupted on a | ||
| frame where a noreturn function is called. This issue doesn't occur | ||
| for every call to noreturn functions, but only for calls such that: | ||
| - the call is the last instruction of the caller function | ||
| - the next function starts immediately after this call instruction; | ||
| in most cases this means that the caller function size is divisible | ||
| by 4 bytes, so no padding is added between the last instruction and | ||
| the next function. | ||
|
|
||
| For example, the following generated code will exhibit this issue: | ||
|
|
||
| esp_system_abort: | ||
| entry a1, 32 | ||
| movi.n a10, a2 | ||
| call8 panic_abort | ||
|
|
||
| some_other_function: | ||
| entry a1, 32 | ||
| ... | ||
|
|
||
| In this case, esp_system_abort function is 3 + 2 + 3 = 8 bytes long, | ||
| so no padding is required before "some_other_function". When the call | ||
| to panic_abort happens, the return address is set to the next | ||
| instruction, i.e. the "entry" instruction of "some_other_function". | ||
|
|
||
| The observed behavior is that the backtrace is interrupted: | ||
|
|
||
| #0 panic_abort (details=0x3ffb5c3b "abort() was called at PC 0x400d485f on core 0") | ||
| at $IDF_PATH/components/esp_system/panic.c:389 | ||
| #1 0x40084fb0 in esp_system_abort ( | ||
| details=0x3ffb5c3b "abort() was called at PC 0x400d485f on core 0") | ||
| at $IDF_PATH/components/esp_system/esp_system.c:129 | ||
| Backtrace stopped: previous frame identical to this frame (corrupt stack?) | ||
|
|
||
| The reason is that when the unwinder inspects the instruction at the | ||
| return address in the caller frame, the instruction is an ENTRY, | ||
| which is part of the next function. Previously it was considered that | ||
| the only case when this can happen is if the frame is the outermost | ||
| frame and the entry instruction hasn't executed yet. | ||
|
|
||
| This commit fixes that assumption, by checking additionally if the | ||
| instruction preceding ENTRY is a call. If it is, the frame is handled | ||
| as usual. | ||
| --- | ||
| gdb/xtensa-tdep.c | 51 ++++++++++++++++++++++++++++++++++++++++++----- | ||
| 1 file changed, 46 insertions(+), 5 deletions(-) | ||
|
|
||
| diff --git a/gdb/xtensa-tdep.c b/gdb/xtensa-tdep.c | ||
| index e18f7a18a5f..d318cfa551b 100644 | ||
| --- a/gdb/xtensa-tdep.c | ||
| +++ b/gdb/xtensa-tdep.c | ||
| @@ -1239,6 +1239,49 @@ xtensa_window_interrupt_frame_cache (struct frame_info *this_frame, | ||
| xtensa_frame_cache_t *cache, | ||
| CORE_ADDR pc); | ||
|
|
||
| +/* Check if the frame should be decoded as if it is the outermost frame, | ||
| + where the ENTRY instruction is about to be executed. */ | ||
| +static bool | ||
| +xtensa_is_frame_entry (struct gdbarch *gdbarch, CORE_ADDR pc) | ||
| +{ | ||
| + gdb_byte buf[4]; | ||
| + int insn; | ||
| + enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); | ||
| + | ||
| + LONGEST op1; | ||
| + if (!(safe_read_memory_integer (pc, 1, byte_order, &op1) | ||
| + && XTENSA_IS_ENTRY (gdbarch, op1))) | ||
| + return false; | ||
| + | ||
| + /* PC points to the ENTRY instruction. However this might be | ||
| + because the previous instruction belonged to another function, | ||
| + and that function was a call to "noreturn" function, e.g.: | ||
| + | ||
| + some_func: | ||
| + entry sp, 32 | ||
| + mov.n a10, a2 | ||
| + call8 panic | ||
| + // no retw.n because "panic" has noreturn attribute | ||
| + next_func: | ||
| + entry sp, 32 // <- return address | ||
| + ... | ||
| + | ||
| + In such case, we need to decode the frame as usual. | ||
| + The code below checks if the instruction at PC-3 is a call/callx. */ | ||
| + | ||
| + read_memory(pc - 3, buf, 3); | ||
| + insn = extract_unsigned_integer (buf, 3, byte_order); | ||
| + | ||
| + /* Decode call instruction. See comment in extract_call_winsize */ | ||
| + if ((byte_order == BFD_ENDIAN_LITTLE && | ||
| + (((insn & 0xf) == 0x5) || ((insn & 0xcf) == 0xc0))) || | ||
| + (byte_order == BFD_ENDIAN_BIG && | ||
| + (((insn >> 20) == 0x5) || (((insn >> 16) & 0xf3) == 0x03)))) | ||
| + return false; | ||
| + | ||
| + return true; | ||
| +} | ||
| + | ||
| static struct xtensa_frame_cache * | ||
| xtensa_frame_cache (struct frame_info *this_frame, void **this_cache) | ||
| { | ||
| @@ -1265,16 +1308,13 @@ xtensa_frame_cache (struct frame_info *this_frame, void **this_cache) | ||
|
|
||
| if (windowed) | ||
| { | ||
| - LONGEST op1; | ||
| - | ||
| /* Get WINDOWBASE, WINDOWSTART, and PS registers. */ | ||
| wb = get_frame_register_unsigned (this_frame, | ||
| gdbarch_tdep (gdbarch)->wb_regnum); | ||
| ws = get_frame_register_unsigned (this_frame, | ||
| gdbarch_tdep (gdbarch)->ws_regnum); | ||
|
|
||
| - if (safe_read_memory_integer (pc, 1, byte_order, &op1) | ||
| - && XTENSA_IS_ENTRY (gdbarch, op1)) | ||
| + if (xtensa_is_frame_entry(gdbarch, pc)) | ||
| { | ||
| int callinc = CALLINC (ps); | ||
| ra = get_frame_register_unsigned | ||
| @@ -1287,7 +1327,8 @@ xtensa_frame_cache (struct frame_info *this_frame, void **this_cache) | ||
| cache->prev_sp = get_frame_register_unsigned | ||
| (this_frame, gdbarch_tdep (gdbarch)->a0_base + 1); | ||
|
|
||
| - /* This only can be the outermost frame since we are | ||
| + /* xtensa_is_frame_entry has checked that the previous instruction | ||
| + is not a call, so this only can be the outermost frame where we are | ||
| just about to execute ENTRY. SP hasn't been set yet. | ||
| We can assume any frame size, because it does not | ||
| matter, and, let's fake frame base in cache. */ |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters